FIELD OF THE INVENTION

The present invention relates to the field of water treatment, more specifically to the use of modified polymers as flocculants for remediation of water, particularly industrial waste water.

BACKGROUND OF THE INVENTION

Wastewaters represent a major problem on a global scale. Many industries generate wastewater which can create significant environmental issues and health hazards. Industrial and agricultural wastewaters cannot be drained off without treatment. Such environmental concerns have continually driven scientists and engineers to develop new materials and methods which can lower the extent of pollution of the environment (Brostow, et al., Materials Letters 61 :4381-4384, 2007 and Craciun et al, J. Materials, 2013).

Flocculation plays a dominant role in wastewater treatment.

Industrial wastewater, for example, can be treated with organic or inorganic flocculating agents such as vinyl polymers and natural polysaccharides (i.e. chitosan, and chitosan grafted with synthetic polymers) and inorganic coagulants. As a result of the complex interdependence between numerous factors inherent in the coagulation and flocculation processes, a good understanding of the phenomena involved is essential. Flocculation is the process whereby particles are formed as a result of destabilization and are induced to come together, make contact and thereby form large and progressively larger agglomerates. In this case, the destabilization is realized in practical terms: flocculation accelerates floe formation, influences the physical characteristics of floes formed (e.g., their strength, size, and density), and governs the final concentration of destabilized particles.

Coagulation is the process of aggregation of colloids induced by particle surface charge neutralization, and/or due to a reversal of surface charges on the particle surface. Both coagulation and flocculation phenomena are extremely important in treatment of wastewater {Coagulation and

Flocculation in Water and Wastewater Treatment, IWA Publishing, 2006). Flocculation is induced by adding small quantities of chemicals in water and Wastewater treatment (Xie, et al, J. Applied Polymer Science 111 :2527-2536 (2009) and Coagulation and Flocculation in Water and Wastewater Treatment, IWA Publishing, 2006). Though the inorganic flocculants (also called coagulants) with multivalent metals like aluminum and iron are widely employed, organic flocculants based on acrylamide- based polymers, like polyacrylamide and its derivatives, are generally more effective than their inorganic counterparts as they possess the advantages of low dose, ease in handling, no effect on pH of the suspensions, and larger floc-forming capability (Xie, et al, J. Applied Polymer Science 111 :2527- 2536 (2009) and Coagulation and Flocculation in Water and Wastewater Treatment, IWA Publishing, 2006).

Flocculants are applied to potable water, industrial raw and process water, municipal sewage treatment, mineral processing and metallurgy, oil drilling and recovery, and other applications (Edzwald, Water Science and Technology 27:21-35, 1993, Fettig, et al, Water Supply 9:19-26, 1991, McCormick, et al, Macromolecules 23:2132-3139, 1990, McCormick et al, Macromolecules 23: 2124-2131, 1990, McCormick et al, ACS Symposium, 1991, Narkis, et al, Water Supply 9:37-44, 1991, and Selvapathy, et al, Water Supply 10: 175-178, 1992). These materials have the ability to induce an advanced coagulation process, after which a large amount of bacteria and viruses from the water are precipitated together with the suspended solids.

Physical and chemical properties of flocculants based on

poly(acrylamide-co-acrylic acid) obtained by electron beam irradiation are tied to the efficiency of wastewater treatment. The efficiency is expressed by the level of treated water quality indicators. There are many situations in which organic flocculants should be used together with classic coagulation aids (inorganic flocculants) such as A1 ₂ (S04)3, FeS0 ₄ , or Ca(OH) ₂ since treatments based only on organic flocculants, or inorganic flocculants (classical treatment), in the treatment of highly charged wastewater are less efficient than when used in combination with other flocculants. Moreover, the so-called floes are larger and more strongly bound than the aggregates obtained by coagulation (Brostow, et al, Materials Letters 61 :4381-4384, 2007 and Craciun et al, J. Materials, 2013).

The effectiveness of polymer flocculation depends on the specific characteristics of the wastewater and the particular polymer used. Not all polymeric flocculants are effective at treating a particular type of wastewater.

Accordingly, there is still a need for polymer flocculants, particularly for modified polymeric flocculants with improved flocculation effectiveness.

Therefore, it is the object of the present invention to provide modified polymeric flocculants for treating wastewater.

It is a further object of the invention to provide methods of making the modified polymeric flocculants.

It is yet another object of the present invention to provide methods of using the modified polymeric flocculants.

SUMMARY OF THE INVENTION

Descried are modified polymeric flocculants with improved flocculant characteristics when compared to the same polymeric flocculants without the modifications. The polymeric flocculants include modified side chains that provide higher degree of flocculant crosslinking, such as a degree of crosslinking of between 0.01% and 1%, increase the stability of the flocculants, provide microbicide function to flocculants, and provide side chains with chemically active groups to react with wastewater contaminants.

Methods of making and using the modified polymeric flocculants are also described. The methods of making the modified polymeric flocculants are performed under mild conditions in water, or in situ without the need to dissolve the polymers in a solvent and purify the resulting product from the reaction mixture.

Disclosed are methods, compounds, and compositions related to wastewater treatment. It has been discovered that large crosslinked polymers serve as effective flocculants. It has also been discovered that such polymeric flocculants can be produced by modifying a base polymer to have active residues on side chains of the polymer through easy reactions in mild conditions. The added active residues can have a number of functions depending on their nature. The preferred or primary function is to mediate crosslinking of the polymer.

Disclosed are polymeric flocculants including a first polymer with side chains and a plurality of first active residues. In some forms, a first set of the first active residues are involved in crosslinks. In some forms, the polymer flocculant has a degree of crosslinking from between 0.01% and 1% of the polymer units. At low degree of crosslinking (between 0.01 and 1%) the polymer is water soluble and has a branched structure. At higher degree of crosslinking, such as at over 1% of polymer units, the number of connections among chains may form crosslinked material that is insoluble in water, but swells in water. The degree swelling is dependent on the degree of branching-crosslinking.

In some forms, the first active residues can be -C(=0)-NHOH, -N=C=0, or combinations thereof. In some forms, the crosslinks of the -C(=0)-NHOH active residues can be complexes of two or more the

-C(=0)-NHOH active residues and a multivalent metal ion. In some forms, the crosslinks of the -N=C=0 active residues can be -NH-C(=0)-NH-, -NH-C(=0)-0-, or combinations thereof. In some forms, the crosslinks of the -C(=0)-NHOH active residues can be

-C(=0)-NHO-

M ²⁺

ONH-C(=0)- where M ²⁺ is a divalent metal ion.

In some forms, the multivalent metal ions can be ions of copper or iron. In some forms, the first polymer is selected from the group consisting of ionic and non-ionic polymers. In some forms, the first polymer can be a copolymer of acrylamide or methacylamide and acrylic acid or methacrylic acid. In some forms, the multivalent metal ions in the complex can be present at a ratio between 1% and 90%> of the -C(=0)-NHOH active residues in the polymer. In some forms, the first polymer can have in average at least one first active residue per 10 side chains along the first polymer. In some forms, the first polymer has a molecular weight of between 5000 and 10000000 Daltons.

In some forms, a second set of the first active residues can be -C(=0)-NHBr, -C(=0)-NHC1, -NH-C(=0)-NHR ¹ , -NH-C(=0)-OR ² , -NH ₂ , -C(=0)-NH ₂ , -N=C=0, or combinations thereof. In some forms, R ¹ and R ² can be independently Ci-C ₂ o alkyl, C ₂ -C ₂ o alkenyl, C ₂ -C ₂ o alkynyl, substituted Ci-C ₂ o alkyl, substituted C ₂ -C ₂ o alkenyl, substituted C ₂ -C ₂ o alkynyl, Ci-C ₂ o alkoxy, Ci-C ₂ o alkylamino, Ci-C ₂ o dialkylamino, hydroxy, aryl, substituted aryl, heteroaryl, substituted heteroaryl, substituted alkoxy, carboxyl, substituted carboxyl, amino, substituted amino, amido, substituted amido, C3-C ₂ o cyclic, substituted C3-C ₂ o cyclic, C3-C ₂ o heterocyclic, or substituted C3-C ₂ o heterocyclic.

In some forms, the second set of the first active residues can be -C(=0)-NHBr, -C(=0)-NHC1, or combinations thereof. In some forms, the second set of the first active residues can be -N=C=0. In some forms, the second set of the first active residues can be -NH-C(=0)-NHR ¹ ,

-NH-C(=0)-OR ² , or combinations thereof. In some forms, the first polymer can have in average at least one first active residue of the second set of the first active residues per 10 side chains along the second polymer.

Also disclosed are flocculant formulations that include one or more of the disclosed polymeric flocculants and a buffer. In some forms, the flocculant formulation further includes a polymeric additive, where the polymeric additive can be a second polymer with side chains and a plurality of second active acid residues. In some forms, the second active residues can be -C(=0)-NHBr, -C(=0)-NHC1, -NH-C(=0)-NHR ¹ , -NH-C(=0)-OR ² , -NH ₂ , -C(=0)-NH ₂ , -N=C=0, or combinations thereof. In some forms, R ¹ and R ² can be independently Ci-C ₂ o alkyl, C ₂ -C ₂ o alkenyl, C ₂ -C ₂ o alkynyl, substituted Ci-C ₂ o alkyl, substituted C ₂ -C ₂ o alkenyl, substituted C ₂ -C ₂ o alkynyl, Ci-C ₂ o alkoxy, Ci-C ₂ o alkylamino, Ci-C ₂ o dialkylamino, hydroxy, aryl, substituted aryl, heteroaryl, substituted heteroaryl, substituted alkoxy, carboxyl, substituted carboxyl, amino, substituted amino, amido, substituted amido, C3-C20 cyclic, substituted C3-C20 cyclic, C3-C20 heterocyclic, or substituted C3-C20 heterocyclic.

In some forms of the flocculant formulation, the second polymer is selected from the group consisting of ionic and non-ionic polymers. In some forms of the flocculant formulation, the second polymer can be a copolymer of acrylamide or methacylamide and acrylic acid or methacrylic acid. In some forms of the flocculant formulation, the second active residues can be -C(=0)-NHBr, -C(=0)-NHC1, or combinations thereof. In some forms of the flocculant formulation, the second active residues can be -N=C=0. In some forms of the flocculant formulation, the second active residues can be -NH-C(=0)-NHR ¹ , -NH-C(=0)-OR ² , or combinations thereof. In some forms of the flocculant formulation, the second polymer can have in average at least one second active residue per 10 side chains along the second polymer. In some forms of the flocculant formulation, the second polymer has a molecular weight of between 5000 and 10000000 Daltons.

Also disclosed are polymeric additives including a second polymer with side chains and a plurality of second active acid residues. In some forms, the second active residues can be -C(=0)-NHBr, -C(=0)-NHC1, -NH-C(=0)-NHR ¹ , -NH-C(=0)-OR ² , -NH ₂ , -C(=0)-NH ₂ , -N=C=0, or combinations thereof. In some forms, R ¹ and R ² can be independently C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, substituted C 1-C20 alkyl, substituted C2-C20 alkenyl, substituted C2-C20 alkynyl, C1-C20 alkoxy, C1-C20 alkylamino, C1-C20 dialkylamino, hydroxy, aryl, substituted aryl, heteroaryl, substituted heteroaryl, substituted alkoxy, carboxyl, substituted carboxyl, amino, substituted amino, amido, substituted amido, C3-C20 cyclic, substituted C3-C20 cyclic, C3-C20 heterocyclic, or substituted C3-C20 heterocyclic.

In some forms, the second polymer is selected from the group consisting of ionic and non-ionic polymers. In some forms, the second polymer can be a copolymer of acrylamide or methacylamide and acrylic acid or methacrylic acid. In some forms, the second active residues can be -C(=0)-NHBr, -C(=0)-NHC1, or combinations thereof. In some forms, the second active residues can be -N=C=0. In some forms, the second active residues can be -NH-C(=0)-NHR ¹ , -NH-C(=0)-OR ² , or combinations thereof. In some forms, the second polymer can have in average at least one second active residue per 10 side chains along the second polymer. In some forms, the second polymer has a molecular weight of between 5000 and 10000000 Daltons.

Also disclosed are kits that include a polymer with side chains and one or a combination of the reagents NH ₂ OH, HOBr, and HOCl, where a set of the side chains include amides. In some forms, the kit further includes R ^! NH2, R ² OH, or both. In some forms of the kit, R ¹ and R ² can be independently C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, substituted C i- C20 alkyl, substituted C2-C20 alkenyl, substituted C2-C20 alkynyl, C1-C20 alkoxy, C1-C20 alkylamino, C1-C20 dialkylamino, hydroxy, aryl, substituted aryl, heteroaryl, substituted heteroaryl, substituted alkoxy, carboxyl, substituted carboxyl, amino, substituted amino, amido, substituted amido, C3-C20 cyclic, substituted C3-C20 cyclic, C3-C20 heterocyclic, or substituted C3-C20 heterocyclic.

In some forms of the kit, the polymer can be selected from the group consisting of ionic and non-ionic polymers. In some forms of the kit, the polymer can be a copolymer of acrylamide or methacylamide and acrylic acid or methacrylic acid. In some forms of the kit, the reagents include NH2OH. In some forms of the kit, the reagents further include HC1 and a multivalent metal ion. In some forms of the kit, the polymer has a molecular weight of between 5000 and 10000000 Daltons.

Also disclosed are methods for treatment of wastewater. In some forms, the method includes bringing into contact on or more of the disclosed flocculant formulations and wastewater. In some forms, the flocculant formulation is at a concentration from 0.0001% to 1% w/w in the

wastewater.

In some forms of the method, the polymeric flocculant of the flocculant formulation includes first active residues and a first and second set of the first active residues. In some forms of the method, the second set of the first active residues can be -N=C=0, where one or more of the -N=C=0 active residues of the second set react with and bond to compounds in the wastewater via hydroxyl groups or amine groups on the compounds, whereby the reacted and bound compounds segregate with the polymeric flocculant. In some forms of the method, the second set of the first active residues can be -C(=0)-NHBr, -C(=0)-NHC1, or combinations thereof, where the -C(=0)-NHBr and -C(=0)-NHC1 active residues have a bactericidal effect on the wastewater.

In some forms of the method, the wastewater originates from an industrial source selected from the group of industrial sources consisting of diamond industry, gold industry, iron industry, steel industry, food and beverage industry, textiles industry, pharmaceuticals industry, chemical industry, agriculture industry, oil separation industry, oil and petrochemicals industry, fracking industry, pulp and paper industry, nuclear industry, electronics industry, and combinations thereof.

Also disclosed are methods of preparing the disclosed polymeric flocculants. In some forms, the method includes adjusting the pH of an aqueous solution including a polymer with amide residues to increase the pH to over 13, adding hydro xylamine hydrochloride in a molar amount between 10% and 100% to the amide residues on the polymer, and mixing at room temperature for at least one hour to form the polymeric flocculant. In some forms of the method, the pH is adjusted by a concentrated solution of sodium hydroxide (NaOH).

Exemplary modified polymeric flocculants include polymeric flocculants with one or more of N-bromoamine, N-chloroamine, hydroxamic acid, and isocyanate side chains. The N-bromoamine or N-chloroamine side chain may, upon controlled cleavage from polymer, release active hypobromous acid (HOBr) or hypochlorous acid (HOCl), which can serve as a powerful antimicrobial agent or detoxification agent for organic molecules such as drugs and toxins. Exposure of organic molecules or biologicals, which typically contain at least one functional group (such as, for example, at least one alcohol, amine, acid, ester, double bond, etc. functional group) to an oxidizing agent (HOBr or HOC1), may result in a degradation of functional groups and inactivation of the agent. Since there are small amounts of such agents in water, a small amount of oxidizing agent may be sufficient. The oxidizing agents released from the brominated or chlorinated acrylamide containing polymers are HOBr or HOC1, or both, depending on the polymer used. These agents may be slowly released from the modified polymer where the active Br ⁺ or Cl ⁺ residues may be slowly cleaved in water and react immediately with water to form BrOH or CIOH, over time (for example, weeks to months, such as over one week, two weeks, three weeks, one month, two months, three months, and longer periods of time). The antimicrobial and the oxidizing effect in water may last as long as there are cleavable halogen units bound to the polymer.

The isocyanate units may hydrolyze in water into amine bonds while releasing C0 ₂ , or react with amine containing molecules to form a urea bond, or react with alcohols to form a urethane bond. The amines formed by hydrolysis may also react with the remaining isocyanate groups on the modified polymeric flocculants. This interaction forms a network of urea bonds between polymer chains. This may serve as a better flocculant due to polymer branching with the increased degree of crosslinking. The

crosslinking forms bonds between polymer chains and makes a sheet-like polymer that has a better surface area coverage compared to linear chains. This results in a larger number of contaminant units (particles and organic molecules) per polymer flocculant, which in turn results in larger and heavier floes that precipitate faster. The crosslinked polymeric flocculants may remove a greater amount of contaminants from the water than non- crosslinked polymeric flocculants applied at the same amount (see Figures 5A and 5B).

An exemplary modified flocculant is a poly(hydroxamic acid) polymers (pHA) with hydroxamic acid side chains. The modified flocculant may contain pHA and multivalent metal ions complexed with the

hydroxamic acid residues of the polymer. Methods for in situ conversion of polymer side chains into hydroxamic acid side chains using hydroxylamine hydrochloride are also described.

The modified polymeric flocculants may be used in wastewater treatment. The wastewater may originate from an industrial source such as the diamond industry, gold industry, iron industry, steel industry, food and beverage industry, textile industry, pharmaceuticals industry, chemical industry, agriculture industry, oil separation industry, oil and petrochemicals industry, fracking industry, pulp and paper industry, nuclear industry, and electronics industry. The method for treating wastewater typically includes bringing into contact an aqueous flocculant formulation containing a polymeric flocculant with wastewater. The method for treating wastewater may include bringing into contact a flocculant formulation in a powder form and containing a polymeric flocculant with wastewater.

The modified polymeric flocculant may be formed of a polymer with ionic and/or hydroxamic acid residues. The modified polymeric flocculant may be present in the wastewater at a concentration from between 0.0001% and 1% w/w. In certain aspects, the amount (by weight) of flocculant to a given type or volume of wastewater to be treated is between about 0.1 mg and 1000 mg per kilogram of wastewater. Suitable amounts include specific amounts between 0.1 mg/kg and 1000 mg/kg wastewater, such as between 1 mg/kg and 800 mg/kg, between 10 mg/kg and 500 mg/kg, between 10 mg/kg and 300 mg/kg, between 10 mg/kg and 250 mg/kg wastewater.

The modified polymer in the polymeric flocculant may be an ionic or a non-ionic polymer. The modified polymer in the polymeric flocculant may be an anionic or a cationic polymer. For example, the polymeric flocculant may be an ionic copolymer of acrylamide or methacylamide and acrylic acid, or methacrylic acid, modified to include anionic side chains or cationic side chains.

The modified polymeric flocculant may include hydroxamic acid residues. The modified polymeric flocculant may be a complex of the polymer and a multivalent metal ion. Examples of multivalent metal ions include divalent metal ions, such as magnesium, calcium, or copper, and/or trivalent metal ions, such as iron, or aluminum. The polymer may form a complex with the multivalent metal ions. The ratio of the multivalent metal ions to the hydroxamic acid residues of the polymer may be between 1% and 90%, such as between 1% and 50%>, between 1% and 45%, between 1% and 33%), between 1% and 25%, or between 1% and 10%, The weight ratio of the multivalent metal ions to the polymer may be between 15:1 and 1 : 1 w/w, such as between 10: 1 and 1 : 1 w/w, between 1 :5 and 1 : 1 w/w, or between 1 :4 and 1 : 12 w/w.

The modified polymeric flocculants may be acrylate copolymers containing hydroxamic acid side chains, in addition to carboxylic acid or acryl amide side groups. The copolymers possess enhanced flocculation activity compared to the corresponding polymers without the hydroxamic acid groups. The molar content of hydroxamic acid units within the polymeric flocculant may be between 10% and 90% of the side chains of the polymer. Generally, the polymeric flocculants include an average of at least one hydroxamic acid residue per 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 acrylamide residues along the polymer chain.

In some aspects, the modified polymeric flocculant is a copolymer containing acrylamide or methacylamide and acrylic acid or methacrylic acid. Typically, the polymer has a number average or weight average molecular weight between 5,000 and 10,000,000 Daltons. The number average or weight average molecular weights for the polymer may be any value between the low molecular weight values of about 10,000 Dalton, 15,000 Dalton, 20,000 Dalton, and 25,000 Dalton, and the high molecular weight values of about 500,000 Dalton, 1 ,000,000 Dalton, 5,000,000 Dalton, 7,000,000 Dalton, and 10,000,000 Dalton. The number average molecular weight of the polymers may be measured by gel permeation chromatography (GPC) or viscosity measurements. The number or weight average molecular weight of the polymer may be varied, so long as the modified polymer remains water soluble or dispersible. The solubility of the polymers and time for solubilization are dependent on the polymer molecular weight. Typically, polymers of over 1,000,000 have limited solubility as they form a gel when dissolving at over 5% wt/v in water and the solubilization may take hours or days. Typically, the modified polymeric flocculant is fully soluble at concentrations required for effective flocculation.

Typically, the multivalent metal ions in the complex are present at a ratio between 1% and 90% of the hydroxamic acid residues in the polymer. The flocculation effectiveness is enhanced in the presence of multivalent metal ions. The metal ions increase the size of the polymer, which then forms large flocks that precipitate.

Methods of making the polymeric flocculants with hydroxamic acid side chains have also been developed. The methods typically include adjusting the pH of an aqueous solution of a polymer, such as acrylamide or methacrylamide, to increase the pH to about or over 13. Hydroxylamine hydrochloride is then added in a molar amount between 10% and 100% to the primary amide residues on the polymer. This mixture is then mixed at room temperature for at least one hour to form the modified polymeric flocculant. Typically, the pH is adjusted by a concentrated solution of sodium hydroxide (NaOH) to about or over 12. Typically, there is no need to reduce the pH to a neutral pH after the formation of the modified polymeric flocculants.

The modified polymeric flocculant, with or without multivalent metal ions, is then added to the wastewater in an amount effective to bind to, and remove at least a portion, such as about 5%, 10%, 20%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, or 99%, of one or more contaminants from the wastewater. The resulting f occulent is then removed mechanically, for example, by filtration.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a line graph of a Fourier transform infrared spectroscopy (FTIR) spectrum (Transmission, %, over wave number (xlO ² , cm ^"1 )) for poly(acrylamide-co-acrylic acid) polymer WAS590 and poly(hydroxamic acid) polymer pHA.

Figures 2A and 2B are line graphs showing FTIR spectra

(Transmission, %) over wave number (xlO ² , cm ^"1 ) for pHA (1) and pHA + Fe ³⁺ (2) at pH 2 (Figure 2A); WAS590 (1) and WAS590 + Fe ³⁺ (2) at pH 3 (Figure 2B).

Figures 3A and 3B are UV absorption spectra (Absorption, a.u., over wavelength (λ, nm) for the supernatants of solutions containing FeCl ₃ at pH 2 (Figure 2 A) or pH 3 (Figure 2B): 1 - initial solution of the salt; 2 - WAS590+FeCl , 3 - pHA+FeCl .

Figures 4 A and 4B are UV absorption spectra (Absorption, a.u., over wavelength (λ, nm) for initial solutions of CuS0 ₄ at pH 4 or 5 (Cu_4 and Cu_5, respectively); supernatants of pHA+CuS0 ₄ solutions at pH 4 or 5 (FJA+Cu_4 and HA+Cu_5, respectively (Figures 4 A and 4B)); supernatants of WAS590+CuSO ₄ solutions at pH 4 and 5 (WAS590+Cu_4 and

WAS590+Cu_5, respectively, Figure 4B).

Figures 5A and 5B are diagrams showing a change in polymer architecture from linear (Figure 5A) to branched with low crosslinking (Figure 5B). The different architectures form floes of different size: small floes are formed with linear polymers without crosslinking (Figure 5A), and large floes are formed with branched polymers with low crosslinking (Figure 5B), when the same linear polymer is modified to have side chains that induce crosslinking, self-crosslinking, or complexing via a metal ion.

DETAILED DESCRIPTION OF THE INVENTION

I. Definitions

"Active residues," as used herein, refers to moieties, groups, or modifications on polymer side chains that can have one or more of the reactivities or effects described herein for active residues. Examples of active residues are the reactive moieties, groups, or modifications shown in Schemes la and lb.

"Bringing into contact," as used herein, refers to causing or allowing compounds, compositions, components, materials, etc. to be in contact with each other. As an example, mixing two components into the same solution constitutes bringing the components into contact. Examples of bringing into contact include adding, combining, and mixing. "Contaminant," as used herein refers to any substance or substances that are not desired in a composition, material, location, etc., such as water. For example, a substance or substances not considered environmentally safe for direct discharge into a drain or other potable water systems can be considered a contaminant. Such substances include, but are not limited to, ions, organics, biochemical reagents, heavy metals, heavy metal complexes, inorganic salts, inorganic reagents, dissolved and colloidal natural organic matter, suspended or colloidal particles, clays, silicas, and any other chemically or biologically active bodies.

"Crosslinks," as used herein in the context of the disclosed polymers, refers to direct or indirect connections between two or more side chains of a polymer or between polymers. Classical crosslinking refers to connections between different molecules (and so, here, can refer to connections between different polymer molecules). Self-crosslinking refers to connections of different parts of the same molecule (for example, connections between different side chains of the same polymer). Metal ion-complexes, while not classical crosslinks, serve the same purpose as crosslinks in the disclosed polymers. For the sake of convenience, and unless the context clearly indicates otherwise, reference to "crosslinks" refers to any of these types of connections. For example, complexes of metal ions and active residues, covalent coupling of active side chains, which can be, for example, direct or through a linker, are examples of crosslinks.

"Degree of crosslinking," as used herein, generally refers to how many connection bonds, on average, connect one polymer chain to another polymer chain. For example, a polymer sample with an average chain length of 1000 units, in which one unit in each chain is connected to another chain, has a degree of crosslinking of 0.1%. A polymer sample with an average chain length of 1000 units, in which 10 units are connected to another chain has a degree of crosslinking of 1%.

"Degree of polymerization," as used herein, generally refers to the number of monomer units along the polymer chain. "Coagulation", as used herein generally refers to aggregation of colloids due to the loss of stability resulting from particle surface charge neutralization and/or due to a reversal of the surface charges on the particle surface.

"Flocculation," as used herein, refers to the destabilization of suspended or colloidal particles present in water caused by such processes as polymer bridging and/or electrostatic interaction and charge neutralization.

"Flocculant" or "flocculating agent," as used herein, may be used interchangeably, and refers to a compound capable, upon application to water containing contaminants, including a plurality of suspended or colloidal particles, of removing some of the contaminants, including particles from suspension in the water to produce purer water. Flocculant is capable of flocculating suspended or colloidal particles. For example, a flocculant can be a polymer or copolymer capable, upon application to wastewater containing a plurality of suspended or colloidal particles, of removing some of the particles from suspension in the wastewater to produce purer water. Flocculants may be organic, or inorganic, or a mixture of organic and inorganic compounds. Flocculant is distinguished herein from "flocculent," which refers to the material that is flocculated by a flocculant.

"Flocculant formulation," as used herein, refers to a composition that includes a flocculant.

"Flocculant/surfactant formulation," as used herein, refers to a single composition that includes a flocculant and a surfactant. A

flocculant/surfactant formulation is a form of flocculant formulation.

"Flocculated material," "flocculated contaminant," "flocculent," "floccule," and "floe," as used herein, refer to a material that is flocculated by a flocculant. For example, the interacting and agglomerated particles formerly suspended or colloidal in water now bound by flocculant constitute a flocculated material. Flocculent is distinguished herein from "flocculant," which refers to a compound capable of flocculating suspended or colloidal particles. "Flocculation activity," as used herein, refers to any action, such as floe formation, the rate of floe formation, floe sedimentation, the rate of floe sedimentation, and/or reduction in the amount (weight, volume, or concentration) of one or more contaminants in wastewater, which is due to the added flocculant (i.e., the action does not occur in the absence of the flocculant). Flocculation activity may be measured by any one or a combination of measuring the amount (weight, volume, or concentration) of floe formation and/or floe sedimentation, the speed of floe formation and/or floe sedimentation the amount (weight, volume, or concentration) of total suspended solids (TSS) remaining in the wastewater following treatment with the flocculant, and the turbidity of the wastewater following treatment with the flocculant.

"Charge neutralization," as used herein, refers to the partial or complete neutralization of a particle charge upon addition of one or more oppositely charged groups.

"Polymer," as used herein, refers to a molecule containing more than 10 monomer units. Polymers may be synthetic or natural and water soluble. In some embodiments, the polymer may be at least partially cationic, anionic, or neutral.

"Polymer bridging," as used herein, refers to the attachment of polymer chain segments to two or more particles in wastewater which links them and induces flocculation.

"Purer water", or "purified water", as used herein, refers to water from which some or all contaminants have been removed. The purity of the water may be defined by the content of Total Organic Carbon (TOC) or by transmission of visible light of 550 nm wavelength through the water sample (percent transmittance, %T). When TOC is used to define water purity, the "purer water" or "purified water" refers to water that has at least 50% less TOC than the original water, as measured by 0.02 M potassium dichromate solution. When percent transmittance is used to define water purity, the

"purer water" or "purified water" refers to water that has at least 50% greater percent transmittance than the original water. It is understood that since what constitutes a contaminant in water depends on what is subjectively considered undesirable, purer water herein can refer to water that includes solutes and other materials not considered contaminants in the context at hand.

"Separating," as used herein, refers to causing or allowing compounds, compositions, components, materials, etc. to no longer be in contact with or in the presence of each other. As an example, removing one component from a solution that also contains another component constitutes, for example, separating the components, separating the first component from the solution, separating the first component from thee second component, and separating the second component from the first component. Examples of separating include isolating, removing, centrifuging, precipitating, sedimenting, and filtering.

"Surfactant," as used herein, refers to a surface active agent that may be anionic, cationic, amphoteric or non-ionic.

"Wastewater" and "effluent water," as used herein, may be used interchangeably to refer to any solution that has water as a primary component and is a discharge, or effluent, that includes one or more contaminants.

Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein.

Use of the term "about" is intended to describe values either above or below the stated value in a range of approx. +/- 10%; in other embodiments the values may range in value either above or below the stated value in a range of approx. +/- 5%; in other embodiments the values may range in value either above or below the stated value in a range of approx. +/- 2%; in other embodiments the values may range in value either above or below the stated value in a range of approx. +/- 1%. II. Modified Polymeric Flocculants

Disclosed are polymeric flocculants with side chains modified to provide improved flocculant characteristics. Flocculants can be classified into overlapping categories such as organic, inorganic, polymeric, anionic, neutral, and cationic. Examples of inorganic flocculants, also known as coagulants, include, but are not limited to, magnesium chloride, calcium oxide, iron (iii) chloride, iron (ii) sulfate, sodium silicate, polyaluminum chloride, aluminum chlorohydrate, polyaluminum chlorohydrate, aluminum sulfate, sodium aluminate, polyaluminum sulfate, polyaluminum silicate chloride, polyaluminum silicate sulfate, and copper sulfate.

Organic flocculants are generally polymeric, and depending on the types of functional groups present in the monomeric units, organic flocculants can be further characterized as anionic, neutral or cationic. Examples of organic flocculants include, but are not limited to,

polyacrylamide, polyalkyleneimines (polyethylene imine), polyacrylamide- co-acrylic acid, polysaccharides, such as chitosan, galactomannans, mucilages, alginate, dextran, and glycogen. It should be noted that some of these polymers may be protonated or deprotonated, depending on the pH of the wastewater.

Typically, the polymeric flocculant will include a backbone, and a reactive side chain, such as an amide, amine, isocyanate, N-bromoamine, and/or N-chloroamine side chains.

The polymer backbone may be formed from polymers that include, but are not limited to, poly(acrylate), poly(methacrylate), poly(acrylamide), poly(methacrylamide), poly( vinyl alcohol), poly(ethylene vinyl acetate), poly( vinyl acetate), polyolefm, polyester, polyanhydride, poly (orthoester), polyamide, polyamine, polyether, polyazine, poly(carbonate),

polyetheretherketone (PEEK), polyguanidine, polyimide, polyketal, poly(ketone), polyphosphazine, polysaccharide, polysiloxane, polysulfone, polyurea, polyurethane, and combinations thereof. The side chains may be chemically modified to provide flocculants with improved characteristics relative to the same polymeric flocculants but without the modified side chains.

In some forms, the polymeric flocculants can include a first polymer with side chains and a plurality of first active residues. In some forms, a first set of the first active residues are involved in crosslinks. In some forms, the polymer flocculant has a degree of crosslinking from about 0.01% to about 1%. In some forms, the polymer flocculant has a degree of crosslinking of about 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, or 1%.

In some forms, the first active residues can be -C(=0)-NHOH, -N=C=0, or combinations thereof. In some forms, the crosslinks of the -C(=0)-NHOH active residues can be complexes of two or more the

-C(=0)-NHOH active residues and a multivalent metal ion. In some forms, the crosslinks of the -N=C=0 active residues can be, independently, -NH-C(=0)-NH- or -NH-C(=0)-0-. In some forms, the crosslinks of the -C(=0)-NHOH active residues can be

-C(=0)-NHO-

M ²⁺

ONH-C(=0)- where M ²⁺ is a divalent metal ion.

In some forms, the multivalent metal ions can be ions of copper or iron. In some forms, the first polymer can be an ionic polymer or a non-ionic polymer. In some forms, the first polymer can be a copolymer of acrylamide or methacylamide and acrylic acid or methacrylic acid. In some forms, the first polymer can be acrylamide or methacylamide. In some forms, the first polymer can be a copolymer of acrylamide and acrylic acid. In some forms, the first polymer can be a copolymer of acrylamide and methacrylic acid. In some forms, the first polymer can be a copolymer of methacrylamide and acrylic acid. In some forms, the first polymer can be a copolymer of methacrylamide and methacrylic acid.

In some forms, the multivalent metal ions in the complex can be present at a ratio between 1% and 90% of the -C(=0)-NHOH active residues in the polymer. In some forms, the multivalent metal ions in the complex can be present at a ratio between 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 14%, 15%, 16%, 18%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or 85% and 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 14%, 15%, 16%, 18%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90% of the -C(=0)-NHOH active residues in the polymer.

In some forms, the first polymer can have in average at least one first active residue per 10 side chains along the first polymer. In some forms, the first polymer can have in average at least 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 2, 3, 4, 5, 6, 7, 8, 9 first active residue per 10 side chains along the first polymer.

In some forms, the first polymer has a molecular weight of between 5000 and 10000000 Daltons. In some forms, the first polymer has a molecular weight of between 5000, 6000, 7000, 8000, 9000, 10000, 12000, 14000, 15000, 16000, 18000, 20000, 25000, 30000, 35000, 40000, 45000, 50000, 55000, 60000, 65000, 70000, 75000, 80000, 85000, 90000, 95000, 100000, 110000, 120000, 125000, 130000, 140000, 150000, 160000, 170000, 175000, 180000, 190000, 200000, 220000, 240000, 250000, 260000, 280000, 300000, 320000, 340000, 350000, 360000, 380000, 400000, 420000, 440000, 450000, 460000, 480000, 500000, 600000, 650000, 700000, 750000, 800000, 850000, 900000, 950000, 1000000, 1100000, 1200000, 1250000, 1300000, 1400000, 1500000, 1600000, 1700000, 1750000, 1800000, 1900000, 2000000, 2200000, 2400000, 2500000, 2600000, 2800000, 3000000, 3200000, 3400000, 3500000, 3600000, 3800000, 4000000, 4200000, 4400000, 4500000, 4600000, 4800000, 5000000, 6000000, 6500000, 7000000, 7500000, 8000000, 8500000, 9000000, or 9500000 and 6000, 7000, 8000, 9000, 10000, 12000, 14000, 15000, 16000, 18000, 20000, 25000, 30000, 35000, 40000, 45000, 50000, 55000, 60000, 65000, 70000, 75000, 80000, 85000, 90000, 95000, 100000, 110000, 120000, 125000, 130000, 140000, 150000, 160000, 170000, 175000, 180000, 190000, 200000, 220000, 240000, 250000, 260000, 280000, 300000, 320000, 340000, 350000, 360000, 380000, 400000, 420000, 440000, 450000, 460000, 480000, 500000, 600000, 650000, 700000, 750000, 800000, 850000, 900000, 950000, 1000000, 1100000, 1200000, 1250000, 1300000, 1400000, 1500000, 1600000, 1700000, 1750000, 1800000, 1900000, 2000000, 2200000, 2400000, 2500000, 2600000, 2800000, 3000000, 3200000, 3400000, 3500000, 3600000, 3800000, 4000000, 4200000, 4400000, 4500000, 4600000, 4800000, 5000000, 6000000, 6500000, 7000000, 7500000, 8000000, 8500000, 9000000, 9500000, or 10000000 Daltons.

In some forms, a second set of the first active residues can be

-C(=0)-NHBr, -C(=0)-NHC1, -NH-C(=0)-NHR ¹ , -NH-C(=0)-OR ² , -NH ₂ , -C(=0)-NH ₂ , -N=C=0, or combinations thereof. In some forms, a second set of the first active residues can be a combination of any six of -C(=0)-NHBr, -C(=0)-NHC1, -NH-C(=0)-NHR ¹ , -NH-C(=0)-OR ² , -NH ₂ , -C(=0)-NH ₂ , -N=C=0. In some forms, a second set of the first active residues can be a combination of any five of -C(=0)-NHBr, -C(=0)-NHC1,

-NH-C(=0)-NHR ¹ , -NH-C(=0)-OR ² , -NH ₂ , -C(=0)-NH ₂ , -N=C=0. In some forms, a second set of the first active residues can be a combination of any four of -C(=0)-NHBr, -C(=0)-NHC1, -NH-C(=0)-NHR ¹ , -NH-C(=0)-OR ² , -NH ₂ , -C(=0)-NH ₂ , -N=C=0. In some forms, a second set of the first active residues can be a combination of any three of -C(=0)-NHBr, -C(=0)-NHC1, -NH-C(=0)-NHR ¹ , -NH-C(=0)-OR ² , -NH ₂ , -C(=0)-NH ₂ , -N=C=0. In some forms, a second set of the first active residues can be a combination of any two of -C(=0)-NHBr, -C(=0)-NHC1, -NH-C(=0)-NHR ¹ , -NH-C(=0)-OR ² , -NH ₂ , -C(=0)-NH ₂ , -N=C=0. In some forms, a second set of the first active residues can be any one of -C(=0)-NHBr, -C(=0)-NHC1, -NH-C(=0)-NHR ¹ , -NH-C(=0)-OR ² , -NH ₂ , -C(=0)-NH ₂ , -N=C=0. In some forms, R ¹ and R ² can be independently C1-C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, substituted C1-C20 alkyl, substituted C2-C20 alkenyl, substituted C2-C20 alkynyl, C1-C20 alkoxy, C1-C20 alkylamino, C1-C20 dialkylamino, hydroxy, aryl, substituted aryl, heteroaryl, substituted heteroaryl, substituted alkoxy, carboxyl, substituted carboxyl, amino, substituted amino, amido, substituted amido, C3-C20 cyclic, substituted C3- C20 cyclic, C3-C20 heterocyclic, or substituted C3-C20 heterocyclic.

In some forms, the second set of the first active residues can be -C(=0)-NHBr, -C(=0)-NHC1, or combinations thereof. In some forms, the second set of the first active residues can be -N=C=0. In some forms, the second set of the first active residues can be -NH-C(=0)-NHR ¹ ,

-NH-C(=0)-OR ² , or combinations thereof. In some forms, the first polymer can have in average at least one first active residue of the second set of the first active residues per 10 side chains along the second polymer. In some forms, the first polymer can have in average at least 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 2, 3, 4, 5, 6, 7, 8, 9 first active residue per 10 side chains along the first polymer.

A. Polymers with Modified Side Chains

The flocculants may be formed from polymers with amide side chains chemically modified into one or more of N-bromoamine, N-chloroamine, hydroxamic acid, and isocyanate side chains.

An exemplary polymer for forming the modified polymeric flocculant may be an acrylamide polymer or copolymer. In one embodiment, the flocculant is an anionic polyacrylamide-co-acrylic acid copolymer. The number or weight average molecular weight of the polymer may be varied, so long as it remains water soluble or dispersible. The polyacrylamide-co- acrylic acid copolymers may be prepared by methods known in the art. The percentage of acryl amide to acrylic or methacrylic acid in the copolymer may vary between 10%: 90% and 90%: 10%. The degree of polymerization may be between 10 and 300,000, such as about 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 1000, 1500, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 6000, 7000, 8000, 9000, 10000, 12000, 14000, 15000, 16000, 18000, 20000, 25000, 30000, 35000, 40000, 45000, 50000, 55000, 60000, 65000, 70000, 75000, 80000, 85000, 90000, 95000, 100000, 110000, 120000, 125000, 130000, 140000, 150000, 160000, 170000, 175000, 180000, 190000, 200000, 220000, 240000, 250000, 260000, 280000, or 300000.

Typically, the polymer has a number average or weight average molecular weight between 5,000 and 10,000,000 Daltons. The number average or weight average molecular weights for the polymer may be any value between the low molecular weight values of about 10,000 Dalton, 15,000 Dalton, 20,000 Dalton, and 25,000 Dalton, and the high molecular weight values of about 500,000 Dalton, 1,000,000 Dalton, 5,000,000 Dalton, 7,000,000 Dalton, and 10,000,000 Dalton. The number average molecular weight of the polymers may be measured by gel permeation chromatography (GPC).

The side chains may be modified with separate chemical reactions, collectively presented in Schemes la and lb.

Schemes la and lb show the disparate chemical modification reactions of acrylamide containing polymers in one diagram. Each arrow represents a different reaction type and a conversion to a different functional group. Two or more of the reactions in Schemes la and lb may be used to modify the same polymeric molecule. The reactions may be performed independently. The reactions may be performed in the same reaction vessel sequentially, or in parallel with one another. All reactions take place in water and at room temperature.

1. Reactions for Forming Polymers with Modified Side Chains

For modifying the polymers to contain the hydroxamic acid side chains, the polymer solution in water should be at pH over 12, such as at pH of about 12.5, 13, or 13.5. Hydroxalamine hydrochloride is then added at a specific ratio to the amide groups desired to be converted. The reaction typically takes place at room temperature. The N-bromo or N-chloro derivatives may be prepared from the reaction of HOC1 or HOBr at a desired ratio. Preferably, the reaction temperature is at low temperature, for example at belowlO°C, such as at 8°C, 5°C, 4°C, 3°C, or 2°C. The reaction time is short, and may be about 30 min, about 40 min, about 50 min, or about 60 min.

The isocyanate may be formed as the next step after forming the Cl-N bond. This may occur at room temperature for a few hours. Heating to 40- 50°C may enhance formation of isocyanate groups, which may increase internal crosslinking with amino groups that are formed from the hydrolysis of the formed isocyanate along the polymer chain.

All reactions may be performed in water, the polymer may be fully soluble and the temperature may be a room temperature or below.

NCO NCO NCO NCO

Scheme lb

Individual reactions from Schemes la and lb are presented in more detail in the following Schemes II-IV.

Scheme II below shows non-limiting exemplary conditions under which polyacrylamide polymers can be reacted to modify at least some of the amide side groups:

Scheme II. wherein each n is an integer value greater than 10, and can be any integer between 10 and 300,000. The modified side groups, as shown on the right side of the reaction arrows, may be present at every repeat unit of the polymer or they may be present at least at about every 5 polymer backbone repeat units, every 10 polymer backbone repeat units, every 20 polymer backbone repeats units, every 30 polymer backbone repeats units, every 40 polymer backbone repeats units, every 50 polymer backbone repeats units, every 60 polymer backbone repeats units, every 70 polymer backbone repeats units, every 80 polymer backbone repeats units, every 90 polymer backbone repeats units, every 100 polymer backbone repeats units, every 200 polymer backbone repeats units, every 300 polymer backbone repeats units, every 400 polymer backbone repeats units, or every 500 polymer backbone repeats units.

In certain cases, where the polyacrylamide polymers have been modified to have isocyanate side groups, as shown in the above Scheme II, the isocyanate side groups may be further subjected to suitable reaction conditions that modify such side groups, as shown in the non-limiting examples of Scheme III below:

Scheme III. wherein each n is an integer value greater than 10, and can be any integer between 10 and 300,000, and wherein each R may independently be any organic residue that can add hydrophobicity or hydrophilicity to the polymer. Such groups include, for example, methyl, butyl, hexyl, triethylene glycol, amino acid, fatty acid chains, and others.

In certain cases, where the polyacrylamide polymers are modified to have isocyanate side groups, the isocyanate side groups may undergo crosslinking with amido containing groups. Amido groups may be present on the polymer chains, thereby resulting in formation of crosslinks between polymer chains. In one non-limiting example, an isocyanate side group may react with an amide side group resulting in crosslinks as shown in Scheme IV belo

Scheme IV.

The product is typically ready to use after completion of the reaction, and there is no need for purification or isolation of the product. Alternatively, the product may be purified, and dissolved in aqueous medium, or lyophilized into powder, and stored until use.

The isocyanate groups in the modified flocculants allow for a range of modifications, including self-branching by forming a larger 2D or 3D structure. The isocyanate groups also allow binding of amine and alcohol functional groups of contaminants to the polymers. The modified polymeric flocculants with the isocyanate groups may include the combination of self- branching properties and the binding of amines and alcohol functional groups of contaminants to the polymers. 2. Poly(hydroxamic acid) (pHA)

Poly(hydroxamic acid) (pHA) and its derivative compounds have been developed as polymeric flocculants. The pHA polymers have been synthesized and investigated (Hassan et al, Chromatography Research International, 2011 : 1-6, (2011) article ID 638090). Polyacrylamides are often considered as starting material for conversion into polyhydroxamic acid (Domb et al., Journal of Polymer Science Part A: Polymer Chemistry, 26(10):2623-2630 (1988); Isikver et al, Polymer Bulletin, 47(l):71-79 (2001); Saraydin et al, Polymer Bulletin, 46(l):91-98 (2001)).

Poly(hydroxamic acid) was shown to chelate heavy metals (Haron et al., Talanta, 41(5):805-807 (1994); Lutfor et al, Journal of Applied Polymer Science, 79(7): 1256-1264 (2001)). It was also shown that hydroxamic acid- derivatives synthesized by different ways, exhibited distinct flocculation activity for removing mineral (oxide) materials (Chen et al., Materials Research Innovations, 19(sup5):S5-163-S5-167 (2015);

Chen et al., Journal of Central South University, 22(5): 1626-1634 (2015)).

Poly(hydroxamic acid) polymers and copolymers with hydroxamic acid side chains have been demonstrated to be useful as flocculants for water purification procedures.

The hydroxamic acid groups in the polymers have a strong complexation affinity to multi-valent metal ions, including to iron and copper ions. This modification allows removal of toxic metal ions from wastewater, as well as forming a network of polymer chains by iron complexation and thereby inducing intermolecular and/or intramolecular binding between polymer chains. The amount of iron needed for forming a network leaves behind a large number of other hydroxamic acids residues, which are free to form complexes with and remove other metal ions.

The chelation of iron or copper ions by pHA provides a polymeric flocculant with improved flocculation capacity relative to the same polymeric flocculant without the hydroxamic acid side chains.

An exemplary polymeric flocculant may contain a polymer with side chains and hydroxamic acid residues. Prior to modification, the polymer may be a copolymer of acrylamide or methacylamide and acrylic acid or methacrylic acid. Following modification, the polymeric flocculant may be a complex of the polymer and a multivalent metal ion. The multivalent metal ions in the complex may be present at a ratio between 1% and 90% of the hydroxamic acid residues in the polymer. The flocculant may have in average at least one hydroxamic acid residue per 10 side chains along the polymer chain. The polymer of the polymeric flocculant may have a molecular weight of between 5,000 and 10,000,000 Daltons.

3. Flocculants as Microbicides

Polymers with modified side chains may have a dual function during wastewater treatment and purification. The polymers of dual function may be prepared by modifying the reactive side chains of polymeric flocculants, such as amide side chains, to include N-bromoamine or N-chloroamine side chains. The modified polymers may function as both a flocculant and a microbicide. The modified polymers may also function as detoxifiers.

For example, the flocculants may be applied to wastewater to induce flocculation as well as complete or partial sterilization of the wastewater sample. The complete or partial sterilization may occur upon controlled cleavage and release from the polymeric flocculant of the active

hypobromide (HOBr) or hypochlorite (HOC1). These can serve as a powerful antimicrobial agents or detoxification agents for organic molecules such as drugs and toxins.

4. Polymers with Isocyanate Side Chains Polymers with modified side chains may include isocyanate side chains. The isocyanate side chains may offer a number of different functions to the polymeric flocculants.

In one aspect, the isocyanate side chains may hydrolyze in water into amine bonds and release C0 ₂ . The amines formed by hydrolysis may also react with a portion or all of the remaining isocyanate groups to form a network of urea bonds between polymer chains. This may serve as an improved flocculant due to its crosslinking and resultant architecture. In another aspect, the isocyanate side chains may react with amine containing molecules, such as contaminants, to form a urea bond and capture contaminants.

In another aspect, the isocyanate side chains may react with alcohol groups of molecules, such as contaminants, to form a urethane bond and capture contaminants.

Thus, the modified flocculants may chemically react with

contaminants to bind to and remove the contaminants from wastewater.

5. Properties of Modified Polymeric Flocculant

a. Structure

The polymeric flocculants, prior to side chain modification, may be linear or branched polymers with a number average or weight average molecular weight between 5,000 and 10,000,000 Daltons. The number average or weight average molecular weights for the polymer may be any value between the low molecular weight values of about 10,000 Dalton, 15,000 Dalton, 20,000 Dalton, and 25,000 Dalton, and the high molecular weight values of about 500,000 Dalton, 1,000,000 Dalton, 5,000,000 Dalton, 7,000,000 Dalton, and 10,000,000 Dalton. The number average molecular weight of the polymers may be measured by gel permeation chromatography (GPC). Typically, the flocculation activity of the modified polymeric flocculants is increased relative to the flocculation activity of unmodified polymeric flocculants of the same molecular weight, same backbone, and used at the same concentration.

The linear polymeric flocculants prior to side chain modification have a first (linear) architecture. The modifications described herein may change structure of the polymeric flocculants to have other polymeric architectures. Different polymeric architectures may be adopted by the modified polymeric flocculants, and may be due to the nature of side chain modification, the degree of crosslinking, or both.

The crosslinked, self-crosslinked, and/or complexed via a metal ion polymers may form polymer networks with different polymer architectures. The crosslinked, self-crosslinked, and metal ion-complexed polymers may have architectures similar to star, comb, brush, dendrimer, dendron, ring, net, web, and other architectures.

The crosslinking, self-crosslinking, or complexing via a metal ion may increase the molecular weight of the modified polymers, such as double, or triple the molecular weight of the modified polymers. In any form, the modified polymers remain water soluble at concentrations used.

b. Stability

The hydroxamic acid polymers are typically stable in water, or in dry form, at room temperature for a period of weeks, months, or years.

The brominated or chlorinated polymers are stable in powder form when the powder is well packed. These polymers are also stable in water solution, although it is expected that some Br or CI may release into the water until an equilibrium is reached.

The modified residues after isocyanate formation and reaction are stable in solid state and in solution.

The stability of the modified polymers may be measured as a length of time during which the modified polymers' flocculation activity remains relatively unchanged when compared to the flocculation activity of a freshly prepared modified polymer. Relatively unchanged is a less than 10% change in flocculation activity over a particular period of time relative to the flocculation activity of a freshly prepared modified polymer. The modified polymers are typically stable in water and/or in dry form, at room

temperature, for a period of weeks, months, or years, such as, for example, for a period of one week, two weeks, three weeks, one month, two months, three months, four months, five months, six months, seven months, eight months, nine months, ten months, eleven months, one year, or more.

c. Solubility

Typically, the modified flocculants are readily soluble in water at concentrations of 1% wt/wt, or 1% wt/v, and below. Exemplary modified polymeric flocculants with a weight average molecular weight of about

5,000,000 Daltons, or 10,000,000 Daltons, may be water soluble when used at concentrations of 1% wt/wt, or 1% wt/v, and below, such as between 0.0001% wt/wt and 1% wt/wt, or between 0.0001% wt/v and 1% wt/v. The modified polymeric flocculant may be present in the wastewater at a concentration of about 0.0001 wt/wt, 0.0002 wt/wt, 0.0003 wt/wt, 0.0004 wt/wt, 0.0005 wt/wt, 0.0006 wt/wt, 0.0007 wt/wt, 0.0008 wt/wt, 0.0009 wt/wt, 0.001 wt/wt, 0.0015 wt/wt, 0.002 wt/wt, 0.0025 wt/wt, 0.003 wt/wt, 0.0035 wt/wt, 0.004 wt/wt, 0.0045 wt/wt, 0.005 wt/wt, 0.0055 wt/wt, 0.006 wt/wt, 0.0065 wt/wt, 0.007 wt/wt, 0.0075 wt/wt, 0.008 wt/wt, 0.0085 wt/wt, 0.009 wt/wt, 0.0095 wt/wt, 0.01 wt/wt, 0.015 wt/wt, 0.02 wt/wt, 0.025 wt/wt, 0.03 wt/wt, 0.035 wt/wt, 0.04 wt/wt, 0.045 wt/wt, 0.05 wt/wt, 0.055 wt/wt, 0.06 wt/wt, 0.065 wt/wt, 0.07 wt/wt, 0.075 wt/wt, 0.08 wt/wt, 0.085 wt/wt, 0.09 wt/wt, 0.095 wt/wt, 0.1 wt/wt, 015 wt/wt, 0.2 wt/wt, 0.25 wt/wt, 0.3 wt/wt, 0.35 wt/wt, 0.4 wt/wt, 0.45 wt/wt, 0.5 wt/wt, 0.55 wt/wt, 0.6 wt/wt, 0.65 wt/wt, 0.7 wt/wt, 0.75 wt/wt, 0.8 wt/wt, 0.85 wt/wt, 0.9 wt/wt, 0.95 wt/wt, or 1%) wt/wt.

d. Viscosity

Typically, the viscosity of the polymers after modification is higher in neutral water. Also, the viscosity of the modified polymer that is crosslinked, self-crosslinked, or complexed with a metal ion is higher when compared to the viscosity of the same modified polymer, at the same concentration, but without crosslinking, self-crosslinking, or complexing with a metal ion. The methods for determination of viscosity are well established, and use the falling ball method or a viscometer.

e. Side Chain Groups

The modified polymers may include one or more types of side chain groups. The types of side chain groups include, but are not limited to, unmodified side chain groups (i.e., the same as prior to the chemical modification reaction); amide groups, N-chloroamide group, isocyanate groups, amine groups, and hydroxamic acid groups.

B. Flocculant Formulations

Flocculant formulations containing at least one modified polymeric flocculant may be prepared as aqueous formulations. Flocculant formulations containing at least one modified polymeric flocculant may be provided as solid pre-measured powders to be mixed at specific proportions with an aqueous medium. In some aspects, the aqueous medium is water and the fiocculant is a water soluble or a water dispersible polymer, wherein the polymer is preferably anionic. Typically, water used for forming flocculants formulations may be tap water, sea water, deionized water, distilled water, double distilled water, deionized water, double deionized water, discharge water, effluent water, or purified water. The pH is preferably neutral, but may be acidic, such as between pH 4 and pH 7, or basic, such as between pH 7 and pH 9.

The fiocculant formulations may contain the modified polymeric flocculants together with one or more additional polymeric flocculants, such as polyalkyleneimines (polyethylene imine), polyacrylamide-co-acrylic acid, polysaccharides, such as chitosan, galactomannans, mucilages, alginate, dextran, and glycogen. The additional organic flocculants may be crosslinked with the modified polymeric flocculants, or interact with the modified polymeric flocculants via non-covalent interactions.

The fiocculant formulations may contain additional components such as surfactants and alkali metal salts such as NaCl and MgCl ₂ . The relative amounts of the additional components in the fiocculant formulation may be varied over a wide range, such as between 0.01% and about 20% (w/w), between 0.1 % w/w and 10%> w/w, or between 1% w/w and 5% w/w of the fiocculant. Salts may be added at an amount between 10% and 300% of the dry weight of the fiocculant.

Fiocculant formulation may contain one or more modified polymeric flocculants, one or more surfactants, one or more polymeric additives, and/or one or more metal ion additives. Multiple fiocculant formulations can be used together in the same method. Multiple polymeric flocculants can be a part of one fiocculant formulation.

Disclosed are fiocculant formulations that include one or more of the disclosed polymeric flocculants and a buffer. In some forms, the fiocculant formulation further includes a polymeric additive, where the polymeric additive can be a second polymer with side chains and a plurality of second active acid residues. In some forms, the second active residues can be -C(=0)-NHBr, -C(=0)-NHC1, -NH-C(=0)-NHR ¹ , -NH-C(=0)-OR ² , -NH ₂ , -C(=0)-NH ₂ , -N=C=0, or combinations thereof. In some forms, R ¹ and R ² can be independently Ci-C ₂ o alkyl, C ₂ -C ₂ o alkenyl, C ₂ -C ₂ o alkynyl, substituted Ci-C ₂ o alkyl, substituted C ₂ -C ₂ o alkenyl, substituted C ₂ -C ₂ o alkynyl, Ci-C ₂ o alkoxy, Ci-C ₂ o alkylamino, Ci-C ₂ o dialkylamino, hydroxy, aryl, substituted aryl, heteroaryl, substituted heteroaryl, substituted alkoxy, carboxyl, substituted carboxyl, amino, substituted amino, amido, substituted amido, C3-C ₂ o cyclic, substituted C3-C ₂ o cyclic, C3-C ₂ o heterocyclic, or substituted C3-C ₂ o heterocyclic.

In some forms of the flocculant formulation, the second polymer can be an ionic polymer or a non-ionic polymer. In some forms of the flocculant formulation, the second polymer can be a copolymer of acrylamide or methacylamide and acrylic acid or methacrylic acid. In some forms of the flocculant formulation, the second active residues can be -C(=0)-NHBr, -C(=0)-NHC1, or combinations thereof. In some forms of the flocculant formulation, the second active residues can be -N=C=0. In some forms of the flocculant formulation, the second active residues can be

-NH-C(=0)-NHR ¹ , -NH-C(=0)-OR ² , or combinations thereof. In some forms of the flocculant formulation, the second polymer can have in average at least one second active residue per 10 side chains along the second polymer. In some forms of the flocculant formulation, the second polymer has a molecular weight of between 5000 and 10000000 Daltons.

1. Surfactants

Surfactants may be liquids. In some aspects, the surfactants may be powders for dissolving in a pre-determined amount of aqueous medium, such as water.

Surfactants include, but are not limited to, sodium lauryl ether sulfate (SLES), TWEEN® 80, SPAN® 20, cocamidopropyl hydroxysultaine (CHSB), poly(diallyl dimethyl ammonium chloride) (PMDC), or

combinations thereof. The surfactants may be dissolved in tap water, double distilled water (DDW), or seawater. Suitable anionic surfactants include, but are not limited to, those containing carboxylate, sulfonate and sulfate ions. Examples of anionic surfactants include sodium, potassium, ammonium of long chain alkyl sulfonates and alkyl aryl sulfonates such as sodium dodecylbenzene sulfonate; dialkyl sodium sulfosuccinates, such as sodium dodecylbenzene sulfonate; dialkyl sodium sulfosuccinates, such as sodium bis-(2- ethylthioxyl)-sulfosuccinate; and alkyl sulfates such as sodium lauryl ether sulfate. Cationic surfactants include, but are not limited to, quaternary ammonium compounds such as benzalkonium chloride, benzethonium chloride, cetrimonium bromide, stearyl dimethylbenzyl ammonium chloride, polyoxyethylene, and coconut amine. Examples of nonionic surfactants include ethylene glycol monostearate, propylene glycol myristate, glyceryl monostearate, glyceryl stearate, polyglyceryl-4-oleate, sorbitan acylate, sucrose acylate, PEG- 150 laurate, PEG-400 monolaurate, polyoxyethylene monolaurate, polysorbates, polyoxyethylene octylphenyl ether, PEG- 1000 cetyl ether, polyoxyethylene tridecyl ether, polypropylene glycol butyl ether, Poloxamer® 401, stearoyl monoisopropanolamide, and polyoxyethylene hydrogenated tallow amide. Suitable amphoteric surfactants include, but are not limited to, compounds such as sodium N-dodecyl-beta-alanine, sodium N-lauryl-beta-iminodipropionate, myristoamphoacetate, lauryl betaine, and lauryl sulfobetaine. Non-ionic surfactants include, but are not limited to, secondary alcohol ethoxylates, decyl glucoside, lauryl glucoside, octyl glucoside, fatty alcohol polyglycol ether, alkylphenol polyglycol ether, fatty acid polyglycol ester, polypropylene oxide -polyethylene oxide mixed polymers, N-methyl myristamide, N-sorbityl lauramide, N-methyl myristamide, N-sorbityl myristamide, and alkyl polysaccharides such as octyl, nonyldecyl, undecyldodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl, di-, tri-, terra-, penta-, and

hexaglucosides, galactosides, lactosides, glucoses, fructosides, fructoses and/or galactoses. 2. Polymeric Additives

Disclosed are polymeric additives that include a second polymer with side chains and a plurality of second active acid residues. Typically, the polymeric additive will include a backbone, and a reactive side chain, such as an amide, amine, isocyanate, N-bromoamine, and/or N-chloroamine side chains.

The polymer backbone may be formed from polymers that include, but are not limited to, poly(acrylate), poly(methacrylate), poly(acrylamide), poly(methacrylamide), poly( vinyl alcohol), poly(ethylene vinyl acetate), poly( vinyl acetate), polyolefm, polyester, polyanhydride, poly (orthoester), polyamide, polyamine, polyether, polyazine, poly(carbonate),

polyetheretherketone (PEEK), polyguanidine, polyimide, polyketal, poly(ketone), polyphosphazine, polysaccharide, polysiloxane, polysulfone, polyurea, polyurethane, and combinations thereof.

The side chains may be chemically modified to provide additives with improved characteristics relative to the same polymeric additives but without the modified side chains.

In some forms, the polymeric additives can include a second polymer with side chains and a plurality of second active residues. In some forms, the second active residues can be -C(=0)-NHBr, -C(=0)-NHC1,

-NH-C(=0)-NHR ¹ , -NH-C(=0)-OR ² , -NH ₂ , -C(=0)-NH ₂ , -N=C=0, or combinations thereof. In some forms, a second set of the second active residues can be a combination of any six of -C(=0)-NHBr, -C(=0)-NHC1, -NH-C(=0)-NHR ¹ , -NH-C(=0)-OR ² , -NH ₂ , -C(=0)-NH ₂ , -N=C=0. In some forms, a second set of the second active residues can be a combination of any five of -C(=0)-NHBr, -C(=0)-NHC1, -NH-C(=0)-NHR ¹ , -NH-C(=0)-OR ² , -NH ₂ , -C(=0)-NH ₂ , -N=C=0. In some forms, a second set of the second active residues can be a combination of any four of -C(=0)-NHBr,

-C(=0)-NHC1, -NH-C(=0)-NHR ¹ , -NH-C(=0)-OR ² , -NH ₂ , -C(=0)-NH ₂ , -N=C=0. In some forms, a second set of the second active residues can be a combination of any three of -C(=0)-NHBr, -C(=0)-NHC1,

-NH-C(=0)-NHR ¹ , -NH-C(=0)-OR ² , -NH ₂ , -C(=0)-NH ₂ , -N=C=0. In some forms, a second set of the second active residues can be a combination of any two of -C(=0)-NHBr, -C(=0)-NHC1, -NH-C(=0)-NHR ¹ , -NH-C(=0)-OR ² , -NH ₂ , -C(=0)-NH ₂ , -N=C=0. In some forms, a second set of the second active residues can be any one of -C(=0)-NHBr, -C(=0)-NHC1,

-NH-C(=0)-NHR ¹ , -NH-C(=0)-OR ² , -NH ₂ , -C(=0)-NH ₂ , -N=C=0.

In some forms, R ¹ and R ² can be independently Ci-C ₂ o alkyl, C ₂ -C ₂ o alkenyl, C ₂ -C ₂ o alkynyl, substituted Ci-C ₂ o alkyl, substituted C ₂ -C ₂ o alkenyl, substituted C ₂ -C ₂ o alkynyl, Ci-C ₂ o alkoxy, Ci-C ₂ o alkylamino, Ci-C ₂ o dialkylamino, hydroxy, aryl, substituted aryl, heteroaryl, substituted heteroaryl, substituted alkoxy, carboxyl, substituted carboxyl, amino, substituted amino, amido, substituted amido, C3-C ₂ o cyclic, substituted C ₃ - C ₂ o cyclic, C3-C ₂ o heterocyclic, or substituted C3-C ₂ o heterocyclic.

In some forms, the second polymer can be an ionic polymer or a non- ionic polymer. In some forms, the second polymer can be a copolymer of acrylamide or methacylamide and acrylic acid or methacrylic acid. In some forms, the second polymer can be acrylamide or methacylamide. In some forms, the second polymer can be a copolymer of acrylamide and acrylic acid. In some forms, the second polymer can be a copolymer of acrylamide and methacrylic acid. In some forms, the second polymer can be a copolymer of methacrylamide and acrylic acid. In some forms, the second polymer can be a copolymer of methacrylamide and methacrylic acid.

In some forms, the second active residues can be -C(=0)-NHBr, -C(=0)-NHC1, or combinations thereof. In some forms, the second active residues can be -N=C=0. In some forms, the second active residues can be -NH-C(=0)-NHR ¹ , -NH-C(=0)-OR ² , or combinations thereof. In some forms, the second polymer can have in average at least one second active residue per 10 side chains along the second polymer. In some forms, the second polymer can have in average at least 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 2, 3, 4, 5, 6, 7, 8, 9 second active residue per 10 side chains along the second polymer.

In some forms, the second polymer has a molecular weight of between 5000 and 10000000 Daltons. In some forms, the second polymer has a molecular weight of between 5000, 6000, 7000, 8000, 9000, 10000, 12000, 14000, 15000, 16000, 18000, 20000, 25000, 30000, 35000, 40000, 45000, 50000, 55000, 60000, 65000, 70000, 75000, 80000, 85000, 90000, 95000, 100000, 110000, 120000, 125000, 130000, 140000, 150000, 160000, 170000, 175000, 180000, 190000, 200000, 220000, 240000, 250000, 260000, 280000, 300000, 320000, 340000, 350000, 360000, 380000, 400000, 420000, 440000, 450000, 460000, 480000, 500000, 600000, 650000, 700000, 750000, 800000, 850000, 900000, 950000, 1000000, 1100000, 1200000, 1250000, 1300000, 1400000, 1500000, 1600000, 1700000, 1750000, 1800000, 1900000, 2000000, 2200000, 2400000, 2500000, 2600000, 2800000, 3000000, 3200000, 3400000, 3500000, 3600000, 3800000, 4000000, 4200000, 4400000, 4500000, 4600000, 4800000, 5000000, 6000000, 6500000, 7000000, 7500000, 8000000, 8500000, 9000000, or 9500000 and 6000, 7000, 8000, 9000, 10000, 12000, 14000, 15000, 16000, 18000, 20000, 25000, 30000, 35000, 40000, 45000, 50000, 55000, 60000, 65000, 70000, 75000, 80000, 85000, 90000, 95000, 100000, 110000, 120000, 125000, 130000, 140000, 150000, 160000, 170000, 175000, 180000, 190000, 200000, 220000, 240000, 250000, 260000, 280000, 300000, 320000, 340000, 350000, 360000, 380000, 400000, 420000, 440000, 450000, 460000, 480000, 500000, 600000, 650000, 700000, 750000, 800000, 850000, 900000, 950000, 1000000, 1100000, 1200000, 1250000, 1300000, 1400000, 1500000, 1600000, 1700000, 1750000, 1800000, 1900000, 2000000, 2200000, 2400000, 2500000, 2600000, 2800000, 3000000, 3200000, 3400000, 3500000, 3600000, 3800000, 4000000, 4200000, 4400000, 4500000, 4600000, 4800000, 5000000, 6000000, 6500000, 7000000, 7500000, 8000000, 8500000, 9000000, 9500000, or 10000000 Daltons.

3. Other Additives

Additional agents can be included in the fiocculant formulations to enhance the flocculating properties of the formulations. For example, an additive can serve as a coagulant that facilitates the formation of particulate aggregates. Any of the metal salts described herein can be used as additives. Examples of additives include alkali metal salts such as NaCl and NaOH, alkaline earth metal salts such as MgCb, CaCb, CaCCb, aluminum sulfate, ferric chloride, copper sulfate, polymerized metal salts such as

polyaluminum chloride, polyaluminum silicate sulfate and oxidants such as hydrogen peroxide.

III. Methods of Making Polymeric Flocculants

A. Synthesis of poly(hydroxamic acid) polymers (pHA).

The polymeric flocculants may be made by reacting a side chain of a polymer, such as an amide side chain of a polymeric flocculant, with hydroxylamine hydrochloride in accordance with Scheme V: HiOH-HCI H

CONH, COMB, -> HO— NH- -C N ^'

pH > 13

o O

PAAni Hydrogen form, of PHA

Scheme V

The exemplary polymer in Schemes la and lb is polyacrylamide (PAAm). However, other polymers with side chains may be used. The polymer has a backbone and a side chain. In Schemes la and lb, the hydroxamic acid group (side chain) is shown as attached to a polymeric backbone (zigzag).

An exemplary side chain is presented in Formula I below, where the side chain is represented by:

Formula I

wherein d is the point of attachment of the side chain to the polymer, wherein R' and R" are absent, or are independently hydrogen, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl, substituted aryl, heteroaryl, substituted heteroaryl, alkoxy, substituted alkoxy, aroxy, substituted aroxy, alkylthio, substituted alkylthio, arylthio, substituted arylthio, carbonyl, substituted carbonyl, carboxyl, substituted carboxyl, amino, substituted amino, amido, substituted amido, amine, amide, sulfonyl, substituted sulfonyl, sulfamoyl, substituted sulfamoyl, phosphonyl, substituted phosphonyl, polyaryl, substituted polyaryl, C3-C20 cyclic, substituted C3-C20 cyclic, heterocyclic, substituted heterocyclic, amino acid, poly(ethylene glycol), poly(lactic-co-glycolic acid), peptide, or polypeptide group.

The polymer backbone is formed from polymers that include, but are not limited to, poly(acrylate), poly(methacrylate), poly(acrylamide), poly(methacrylamide), poly( vinyl alcohol), poly( ethylene vinyl acetate), poly( vinyl acetate), polyolefm, polyester, polyanhydride, poly (orthoester), polyamide, polyamine, polyether, polyazine, poly(carbonate),

polyetheretherketone (PEEK), polyguanidine, polyimide, polyketal, poly(ketone), polyphosphazine, polysaccharide, polysiloxane, polysulfone, polyurea, polyurethane, combinations thereof.

The reaction is performed at pH over 10, typically at pH over 13. The pH may be adjusted with sodium hydroxide, or any other suitable hydroxide.

Typically, the molar ratio of the side chains to hydroxylamine hydrochloride is between 1 :1 and 1 : 100. Alternatively, the ratio may be between 1 : 1 and 1 : 100 weight/weight (w/w), or between 1 : 1 and 1 : 1000 weight percent (wt.%).

1. Exemplary Method of Making pHA The synthesis of an exemplary poly(hydroxamic acid) using a high molecular weight copolymer of acrylamide and acrylic acid (MW 5xl0 ⁶ ) and hydroxyl amine hydrochloride may be conducted at room temperature, under standard pressure, using routine laboratory or industrial equipment.

An exemplary method of making a modified polymeric flocculant includes the steps of:

adjusting the pH of an aqueous solution comprising a polymer with amide residues to increase the pH to over 13, adding hydroxylamine hydrochloride in a molar amount between 10% and 100% to the amide residues on the polymer, and

mixing at room temperature for at least one hour to form the polymeric flocculant.

The pH may be adjusted by a concentrated solution of sodium hydroxide (NaOH).

First, a commercially available polymer, such as a copolymer of acrylamide and acrylic acid (MW 5xl0 ⁶ ) is dissolved in water with by stirring the solution on a magnetic stir plate until dissolved, such as for about 1 h. Then, an appropriate amount of hydroxyl amine hydrochloride is added to convert acrylamide residues along the polymer chain into hydroxamic acid residues. The mixture is left to react for 30 min at room temperature.

Then, a strong base, such as NaOH (50%> w/w) is added to the polymer solution. Ammonia gas may be generated and it may be evaporated out during the reaction. The gas may serve as an indicator of the progress of the reaction. After 24 h, gas nitrogen is passed through the solution for 2 minutes for removal of ammonia. Then the polymer solution may continue to mix for another 2 hours, after which the pH of the solution is adjusted to about pH=7 by addition of 50% (v/v) H ₂ S0 ₄ .

The pHA solution may be used as prepared. Alternatively, the polymer solution at pH=7 may be precipitated in methanol to obtain pure pHA. The purified polymer may be used as a flocculant as prepared. The purified polymer may also be combined with metal ion additives prior to use as a flocculant.

Therefore, the flocculants are prepared from the chemical

modification of polymers commonly used for water treatment. More specifically, the disclosed method chemically modifies the polymers under mild conditions in water, and can be performed in situ without the need to dissolve the polymers in a solvent and purify the resulting product from the reaction mixture. The modifications take place in most cases in water, at room temperature with the addition of common chemicals that convert part of the amide groups along the polymer chain into either hydroxamic acid groups that have strong complex ation affinity to multi-valent metal ions. The pHA polymers form stable complexes with multi-valent metal ions, such as iron and copper ions.

The pHA, or the pHA complexed with metal ions, are modified flocculants and allow removal of toxic metal ions from wastewater and a greater amount of contaminants by forming a network of polymer chains by iron complexation and binding between polymer chains.

B. Complexes of multivalent metal ions and pHA polymers.

The polymeric matrix of pHA may be suitable for forming complexes with multivalent ions, such as divalent or trivalent, metal ions. Formation of such a complex may follow the side chain and metal ion interactions as presented in Scheme VI:

Scheme VI wherein M ⁺² is a divalent metal ion complexed to the pHA side chains (Hassan et al, Chromatography Research International, 2011 :l-6, (2011) article ID 638090). The complexed metal ion may be a multivalent metal ion (M ⁿ⁺ ), such as iron, or aluminum, or other multivalent metal ions suitable for water purification.

pHA polymer is a known chelator of divalent metals. The pHA polymeric flocculants described herein show improved flocculation efficiency over polymeric flocculants devoid of hydroxamic acid group, whether used alone or when complexed with divalent and/or trivalent metal ions (Tables 3 and 4).

For example, pHA polymeric flocullants, optionally complexed with multivalent metal ions, may have increased flocculation activity (efficiency) relative to polymeric flocculants devoid of hydroxamic acid group. The increased efficiency may be between 0.1 and 100 fold. The flocculation efficiency may be established by determining total suspended solids (TSS, mg/L) and/or turbidity (FAU) of a given sample before and after treatment with respective polymeric flocculants using standard techniques known in the art. A reduction in TSS (mg/L) of between 0.1 and 100 fold following treatment with pHA polymeric flocculant over the reduction in TSS (mg/L) following treatment with a polymeric flocculant devoid of hydroxamic acid group, may indicate that the pHA polymeric flocculant has a greater flocculation efficiency relative to the polymeric flocculant devoid of hydroxamic acid groups.

IV. Methods of Using the Formulation

The modified flocculant may be mixed or combined with wastewater. The modified flocculant may be combined with the wastewater in the presence or absence of additives. The flocculants may be applied as aqueous formulations at the same time (i.e., simultaneously) or separately (i.e., at different times) as the multivalent metal ions to the wastewater to be treated. The addition of a surfactant may aid in dispersing the flocculant in the wastewater. The flocculant is then more readily able to induce flocculation of contaminants present through processes such as electrostatic interaction, charge neutralization, and/or polymer bridging. Subsequently, a step of isolating, separating, or filtering the flocculated contaminants from the treated water is performed to yield a purified or highly purified water. In some aspects, the method does not include bubbling or any step which results in formation of bubbles for the purposes of treating wastewater.

In some aspects, the flocculant formulation applied to treat the wastewater is in the form of an aqueous solution containing an anionic polymer, such as a polyacrylamide-co-acrylic acid copolymer. The flocculant formulations may contain additional components such as surfactants, alkali metal salts, and oxidants.

In certain aspects, an aqueous surfactant is applied during wastewater treatment. The aqueous formulation may contain an ionic, amphoteric, or neutral surfactant. In some embodiments, the surfactant is selected from the group consisting of sodium lauryl ether sulfate (SLES), TWEEN® 80, SPAN® 20, cocamidopropyl hydroxysultaine (CHSB), and

poly(diallyldimethyl ammonium chloride) (PMDC).

In one aspect of the method, the addition of a surfactant reduces the amount of the flocculant formulation needed to achieve the same results as with the flocculant formulation free of a surfactant. In some aspects, the use of a surfactant in combination with a flocculant formulation reduces the volume of the flocculant formulation needed by at least about 50% (by volume) in comparison to a treatment without the addition of the surfactant. In certain aspects, the addition of a surfactant allows for the amount of flocculant formulation to be reduced by at least about 55%, 65%, or up to about 75%) (by volume).

The wastewater or the effluent water may include emulsions at not more than 50%, 45%, 40%, 35%, 30%, 25%, 20%, 15%, 10%, 5%, 4%, 3%, 2%), or 1%) by volume. In some aspects, the wastewater or effluents to be treated are free of, or do not contain a detectable amount of, emulsions. The amount of emulsions may be detected by suitable methods used in the art, such as visual observation, light transmission, dynamic light scattering, and microscopy.

The method of wastewater treatment may be combined with other commercially available treatment processes or chemical formulations. These include various types of filtrations, disinfections, and chemical treatments known in the art.

The method can be applied to an existing water treatment processing facility. The method can be applied at any point in the water treatment plant purification process. The method may be applied at an early step in the water treatment process. The modified polymers may be used in the pre -treatment of wastewater in the first stage of removal of the main solids and organics. The modified polymers may be used in any stage of water treatment in suitable quantities for de-activation of bacteria, and/or enhanced removal of toxic metal ions.

A. Method Parameters

The method can be varied to remove a portion, the majority, or all of contaminants present in wastewater. Those skilled in the art will recognize that the source and composition of the wastewater or effluent water sample will affect the treatment conditions required, such as the relative volumes of flocculant and/or surfactant to be applied and the treatment times required for treating of the wastewater or effluent water. It is well known that each type of wastewater, depending on its origin, will have its own particularities and that within the same class or type of wastewater significant variations may be encountered.

The pH of the wastewater may affect the activity of flocculants and surfactants. In certain embodiments of the method, the pH of the wastewater may be adjusted, as appropriate, in order to improve the efficiency of the treatment process. If the wastewater or effluent water to be treated is highly acidic (pH < 3) or highly basic (pH > 10), the pH of the water may be preferably adjusted to a pH in the range of about 4-9 prior to discharge of the treated water. In some embodiments the pH of the water is adjusted to a pH of between about 5-8, 6-7, or to a pH of about 7 (i.e. neutral pH) prior to discharge.

In certain aspects, the amount (by weight) of flocculant and/or surfactant, added separately or in combination, to a given type or volume of wastewater to be treated is between about 0.1 mg and 1000 mg per kilogram of wastewater. Suitable amounts include specific amounts between 0.1 mg/kg and 1000 mg/kg wastewater, such as between 1 mg/kg and 800 mg/kg, between 10 mg/kg and 500 mg/kg, between 10 mg/kg and 300 mg/kg, between 10 mg/kg and 250 mg/kg wastewater.

The weight to weight (w/w) ratio of surfactant composition (in dry form) to flocculant composition (in dry form) may be in the range between about 0.01 and about 10, such as between 0.1 and 10, between 0.01 and 5, or between 0.1 and 5. The use of surfactants with the flocculant formulation may maximize the efficiency of the treatment and minimize the amount of flocculant used.

In some embodiments, the step of bringing a flocculant and a surfactant into contact with wastewater includes adding, combining, or mixing the flocculant, optionally with a surfactant, with the wastewater and applying some form of agitation or mixing. Agitation may include, but is not limited to, mechanical stirring or acoustic (i.e. sonication-based) forms of mixing, to ensure sufficient adequate contact of the contaminants present in the wastewater with the flocculant and surfactant. In certain embodiments, agitation or mixing is performed for a few seconds up to about 2 minutes, 4 minutes, 5 minutes, 8 minutes, 10 minutes, 15 minutes, 20 minutes, or 30 minutes. The mixture may be allowed to stand for 30 minutes, 60 minutes, 90 minutes, or longer to precipitate or sediment the flocculents. Typically, the treatment is conducted at room temperature.

In certain aspects, the combination or mixture of flocculant, optionally with surfactant, and wastewater is allowed to stand for a sufficient amount of time to allow for flocculation and sedimentation of contaminants from the wastewater to occur. In certain embodiments, sedimentation time is in the range of about 30 seconds up to about 5 hours, as determined by visual observation of sedimentation followed by UV transmission measurement.

In some aspects, the treatment is applied to wastewater is at or near room temperature. In some embodiments, the temperature of the wastewater at which the method is applied may vary. In some aspects, the treatment is applied at temperatures between about 25 °C up and about 70 °C, such as between about 30 °C and about 60 °C, between about 35 °C and 50 °C, or between about 25 °C and about 40 °C. In other aspects, the treatment is applied at temperatures between about 5 °C and about 25 °C, such as between about 18 °C and about 25 °C, or 10 °C and about 25 °C.

An exemplary method for treatment of wastewater includes the steps of: bringing into contact an aqueous flocculant formulation comprising a polymeric flocculant comprising a polymer with side chains and hydroxamic acid residues to wastewater at a concentration from 0.0001% to 1% w/w. The polymer may be selected from the group consisting of ionic and non-ionic polymers. The polymeric flocculant may be an ionic copolymer of acrylamide or methacylamide and acrylic acid or methacrylic acid. The polymeric flocculant may be a complex of the polymer and a multivalent metal ion. The multivalent metal ions in the complex may be present at a ratio between 1% and 90% of the hydroxamic acid residues in the polymer. The multivalent metal ions may be ions of copper or iron. The wastewater may originate from an industrial source selected from the group consisting of diamond industry, gold industry, iron industry, steel industry, food and beverage industry, textiles industry, pharmaceuticals industry, chemical industry, agriculture industry, oil separation industry, oil and petrochemicals industry, fracking industry, pulp and paper industry, nuclear industry, and electronics industry.

B. Improved Flocculation

The improvement in flocculation by the modified polymeric flocculants is provided in part by 1) modifying the

polymerization/crosslinking, and therefore, the architecture, of the polymers; 2) by providing chemically active side chain groups that are the same side chain groups; 3) by providing chemically active side chain groups that are of two or more different types of side chain groups; or 4) a combination thereof.

The modified polymeric flocculants may remove a higher amount of contaminants, including particles, from wastewater when compared to the same polymeric flocculants but without the modified side chains.

The modified polymeric flocculants may remove the contaminants faster than the unmodified polymeric flocculants. The kinetics of

contaminant removal may be measured by monitoring the rate of flocking and the density of the precipitate. The larger the f oes, the faster their precipitation with low water content.

A method of wastewater treatment using one or more of the modified flocculants may produce a purer water with the amount of contaminants in the purer water reduced by about 5%, 10%, 20%, 40%, 50%, 60%, 70%, 80%), 90%), 95%), or 99% relative to the wastewater not treated by the one or more of the flocculants with modified side chains.

A method of wastewater treatment using one or more of the modified flocculants may produce a purer water with the amount of contaminants in the purer water reduced by about 5%, 10%, 20%, 40%, 50%, 60%, 70%, 80%), 90%), 95%), or 99% relative to the wastewater treated by the same method but using the polymeric flocculants with the same backbone and without the modified side chains.

The reduction in the amount of contaminants may be detected by measuring the amount of total suspended solids (TSS) remaining in the wastewater following the treatment with the flocculants. The reduction in the amount of contaminants may be detected by measuring the turbidity of the water following the treatment with the flocculants. In some aspects, the TSS and the turbidity may be measured to detect the reduction in contaminants. V. Kits

Kits may provide flocculant formulations, surfactants, additives, or combinations thereof. The formulations may be provided in ready to use aqueous form, or in powder form.

Kits may provide the flocculant compositions, the surfactant compositions, the additives, or any combination thereof, in a pre -measured powder mix ready to be dissolved in a specified volume of an aqueous medium, such as water.

Kits may provide the reactants needed to form the modified polymeric flocculants. Reactants for forming the modified polymeric flocculants include hydroxylamine hydrochloride, hypobromous acid or hypobromide, hypochlorous acid or hypochlorite, NaOH or KOH, and metal ion additives, such as magnesium chloride, calcium oxide, iron (iii) chloride, iron (ii) sulfate, sodium silicate, polyaluminum chloride, aluminum chlorohydrate, polyaluminum chlorohydrate, aluminum sulfate, sodium aluminate, polyaluminum sulfate, polyaluminum silicate chloride, polyaluminum silicate sulfate, and copper sulfate. The materials described above as well as other materials can be packaged together in any suitable combination as a kit useful for performing, or aiding in the performance of, the disclosed method. It is useful if the kit components in a given kit are designed and adapted for use together in the disclosed method. For example disclosed are kits for forming fiocculants, the kit comprising aqueous or powder forms of one or more of the fiocculants with modified side chains described above. The kits also can contain aqueous or powder forms of one or more metal ion salts.

Disclosed are kits that include a polymer with side chains and one or a combination of the reagents NH2OH, HOBr, and HOC1, where a set of the side chains include amides. In some forms, the kit further includes R^N b, R ² OH, or both. In some forms of the kit, R ¹ and R ² can be independently Ci- C20 alkyl, C2-C20 alkenyl, C2-C20 alkynyl, substituted C1-C20 alkyl, substituted C2-C20 alkenyl, substituted C2-C20 alkynyl, C1-C20 alkoxy, C1-C20 alkylamino, C1-C20 dialkylamino, hydroxy, aryl, substituted aryl, heteroaryl, substituted heteroaryl, substituted alkoxy, carboxyl, substituted carboxyl, amino, substituted amino, amido, substituted amido, C3-C20 cyclic, substituted C3-C20 cyclic, C3-C20 heterocyclic, or substituted C3-C20 heterocyclic.

In some forms of the kit, the polymer can be an ionic polymer or a non-ionic polymer. In some forms of the kit, the polymer can be a copolymer of acrylamide or methacylamide and acrylic acid or methacrylic acid. In some forms of the kit, the polymer can be acrylamide or methacylamide. In some forms of the kit, the polymer can be a copolymer of acrylamide and acrylic acid. In some forms of the kit, the polymer can be a copolymer of acrylamide and methacrylic acid. In some forms of the kit, the polymer can be a copolymer of methacrylamide and acrylic acid. In some forms of the kit, the polymer can be a copolymer of methacrylamide and methacrylic acid.

In some forms of the kit, the reagents include NH2OH. In some forms of the kit, the reagents further include HC1 and a multivalent metal ion. In some forms of the kit, the polymer has a molecular weight of between 5000 and 10000000 Daltons. Examples

The present invention will be further understood by reference to the following non-limiting examples.

Example 1. Synthesis of poly(hydroxamic acid).

Materials and methods

Materials

A solution of NaOH (50% w/w) for synthesis of poly(hydroxamic acid) (pHA) was prepared by adding NaOH pellets (Daejung, 50 g) to DDW (50 ml). A 50% solution of H ₂ S0 ₄ was made with adding H ₂ S0 ₄ (98%) to DDW by droplet addition. Sodium acetate buffer was at 0.1M. Commercial sample of WAS590 - the copolymer of acrylamide-co-acrylic acid

(MW>5000000) was obtained from Mosmart Ltd. Hydroxyl amine hydrochloride (REAGENTPLUS®, Sigma Aldrich, 99%) was used as a modifier of WAS590.

Methods

The synthesis of poly(hydroxamic acid) was conducted using

WAS590, a commercial brand of high molecular weight copolymer of acrylamide and acrylic acid (MW 5xl0 ⁶ )

150 mL DDW were transferred to a 250 mL glass jar and set on a stir plate with magnetic stirrer at room temperature. Then, 2 grams of WAS590 were added to the glass jar within stirring for 1 h, until WAS590 was dissolved. Then, an appropriate amount of hydroxyl amine hydrochloride was added to convert acrylamide residues along the polymer chains into hydroxamic acid residues. The mixture was left to react for 30 min at room temperature. The conversion into hydroxamic acid residues was correlated with the ratio of reacted hydroxylamine hydrochloride and the amide residues along the polymer chain.

Then, 6 mL of NaOH (50%> w/w) were added to the polymer solution. Ammonia gas was generated, and was evaporated out during the reaction. It served as indicator of the progress of the reaction. After 24 h, gas nitrogen was passed in each solution for removal of ammonia for 2 minutes. Then the polymer solutions were mixed for another 2 hours. This process was repeated twice. The total time for the reaction was 28 h. When the reactions were stopped, the pH of each solution was adjusted to pH=7 by addition of 50%(v/v) H2SO4.

For analysis, the polymer solutions were diluted to 200mL by addition of DDW. From the polymer solution at pH=7, 10 mL (containing 100 mg of pure polymer) were used to precipitate in methanol to obtain pure pHA. Purified polymer was studied by means of elemental analysis and FTIR (Nicolet iSlO, Thermo Scientific).

The ratios of reagents used during the pHA synthesis are presented in Table 1.

Table 1. Stoichiometric ratios of reagents used during the poly(hydroxamic acid) synthesis.

Results

The results obtained from the infrared spectroscopy showed characteristic bands for WAS590 and hydroxamic acid as derivative (Figure 1). WAS590 demonstrates strong C=0 stretching vibration, corresponding to the amide I band (1650 cm ^"1 ). This band represents a doublet - the additional deformation vibration of NH ₂ corresponds to 1600 cm ^"1 accompanied with the band at 1590 cm ^"1 - amide II, which in primary amides is characterized by weak or middle intensity. The medium-intensity peaks, attributed to the symmetrical N-H stretching vibrations of free primary amide groups, are located at 3400 cm ^"1 , whereas associated amide groups are characterized by 3200 cm ^"1 (symmetrical N-H stretching).

Regarding HA-based derivative polymer, three stretching vibrations within the 2800 - 3300 cm ^"1 of weak and medium intensities were observed, and are associated with O-H and N-H. Hydroxamic acid features were in the specific carbonyl absorption at 1650 cm . As the main indicator of a secondary amide, which is related to pHA too, a strong 1550 cm ^"1 band (amide II) was (Figure 1). An additional band, characteristic of hydroxamic acids, was observed at 1400 cm ^"1 . Usually, it is of variable intensity and can lie over 1360 - 1440 cm ^"1 , which is responsible for the bending vibration of N-H bending vibration. Additional band observed at 1325 cm ^"1 corresponds to the stretching vibration of the C-N bond (amide III). Thus, a substitution with a formation of -NH-CO2H groups had been performed successfully. These result correspond with those from the monograph study (Socrates, G., Infrared Characteristic Group Frequencies. 1980, Chichester: Wiley, pi 53.) and other studies (Artemenko et al, Journal of Applied Spectroscopy, 32(4):357-362 (1980); Bhawani et al, Journal of Chemical and

Pharmaceutical Research, 6(5):925-930 (2014); and Khaled et al,

Chromatography Research International, 638090 (2011)).

Example 2. pHA forms a complex with Iron (Fe ³⁺ ) ions.

Materials and Methods

Anhydrous FeCb was used to study the chelation of Fe ³⁺ cations by polymers. The chelation of Fe ³⁺ was performed at different pH: pH 2 or pH 3. The solutions of FeCb at different pH were prepared by dissolving 250 mg of FeCb in 50 mL of buffer acetate (sodium acetate + acetic acid, 0.1 M). Then 10 mL of the polymer solution (100 mg of polymer) and 6.6 mL of buffer solution (33 mg of FeCb) were added to a plastic vial. The obtained solution was intensively stirred (30 s). Thereupon, the mixture was left under moderate stirring (100 rpm) at room temperature for 24 h.

After 24 h, the polymer-Fe ³⁺ solutions were centrifuged (15 min,

4000 rpm, 21 °C). The supernatants were taken from each solution and the concentration of the Fe ⁺³ was determined using a 2100 pro (Ultrospec™) spectrophtometer from the calibration curve Fe ³⁺ at λ = 380 nm (the charge transfer band in Fe0 ₆ coordination). Asa reference solution, the supernatant from WAS590 and Fe ³⁺ system was used under similar conditions. The precipitants of the polymer-Fe ³⁺ complexes were dried via liophilization, then washed to remove NaCl, and heated at 50 °C. Photographs of all the test solutions and dried cakes were obtained. The results are shown in Table 2.

Results

Table 2. Chelation summary of Fe ³⁺ at pH 2 and 3 by WAS590 or pHA.

5

FTIR spectra of the Fe ³⁺ -WAS590 or Fe ³⁺ -pFJA complexes (Figures 2A and 2B) indicate that bands involved in complexation (OH and C=0) changed their main characteristics: intensities and energy positions (wave 0 numbers) - due to the alterations in symmetry of molecules. Additionally, the broadening C=0 band supports the conclusion about the coordination with Fe ³⁺ . It is an effect of C-0 electronegativity transfer, when carbonyl group loses its double-bond nature reacting with metal ions. See also the infrared spectra of Lee at al. (Lee et al, Fibers and Polymers, 2(1): 13-17 (2001)). 5 Fe ³⁺ -WAS590 complex, however, did not involve the OH-groups into the process of iron cation chelation, which is supported by the pictures of test solutions. Thus, there was no natural complexation, but interaction between carboxylic groups in polyacrylic fraction of WAS 590 that contributed to the formation of Fe ³⁺ -containing compound. The properties of the equipment 0 used did not allow detection of bands below 1000 cm ^"1 , which would have allowed detection of Fe ³⁺ -0 bonds (ca. 750 - 800 cm ^"1 ). Detailed summary of results obtained from Fe ³⁺ chelation by

WAS590 or pHA in acidic media is shown in Table 2. The observations indicate higher complexation ability of pHA towards ferric ions, whereas chelating activity of WAS590 increased with an increase in pH from 2 to 4. At pH 4 both polymers exhibited similar complexation effects. Considering absolute values of optical absorption, it was concluded that the difference in bonding Fe ³⁺ was important. Although the resulting supernatants had no absorption in the visible light range, Αλ=380 values indicated a strict tendency (Figures 3 A and 3B). The dried samples of lyophilized solutions saved their original colors and were used for FTIR studies.

Example 3. pHA forms a complex with Copper (Cu ²⁺ ) ions.

Materials and Methods

In case of Cu ²⁺ chelation, CuS0 ₄ · 6H ₂ 0 was used. A solutions of CuS0 ₄ at pH 4 or 5 were prepared by dissolving lg of CuS0 ₄ anhydrous (calculated from the crystallohydrate of the original salt) in 50 mL of acetate buffer at pH5. The pH was adjusted by NaOH (50%w/w) or H ₂ S0 ₄ (50%v/v) to pH 4 or 5, respectively.

10 mL of the polymer solution (100 mg of polymer) were added to a plastic vial at a mol/mol ratio of 1/0.33 of polymer/CuS0 ₄ (3 mL of CuS0 ₄ buffer solution). The solutions were intensively stirred for 30 s. After 24 h, the polymer-Cu ²⁺ solutions were centrifuged (15 min, 4000 rpm, 21 °C). The supernatants were taken from each solution and the concentration of Cu ²⁺ in each polymer solution was determined using a 2100 pro (Ultrospec™) spectrophotometer and a calibration curve for Cu ²⁺ at λ = 750 nm ( ² T _2g → ² E _2g , d-d transition). As reference solution, the supernatant from WAS590 + Fe ³⁺ system was used under similar conditions.

Results

The chelation profile of Cu ²⁺ by the polymers is reflected in Figures 4 A and 4B. The introduction of pHA proved effective in eliminating copper ions from the solutions. The reference copolymer - WAS590 - showed weak chelating activity, resulting in high turbidity and colorization of supernatant solutions after centrifugation. The absorbance values of the supernatants of pHA+Cu ²⁺ complexes were indicated to lie at the noise level. Thus, synthesized pHA is an effective chelator-precipitator for Cu ²⁺ .

Example 4. Flocculation activity of pHA alone, or pHA with Fe ³⁺ is greater than that for WAS590 alone, or WAS590 with Fe ³⁺ .

Materials and methods

Hydroxamic acid polymers were prepared in situ from commercially available copolymer - poly(acrylamide-co-acrylic acid) by conversion of co- NH ₂ to CO-NH-OH in order to obtain a chelator for a well-known coagulant FeCb.

Jar tests were carried out as follows. Into each 20 mL glass vial a small X-shaped magnetic stirrer was placed and the vial was placed on a magnetic plate. 15 mL of scrubber water (SW) was added into each vial.

The indicated amount of FeCb solution (200 ppm) was added to the samples and the samples were mixed for 2 min at room temperature (Sample SW1). After 2 min, WAS590 or pHA were introduced in amounts 50 or 100 ppm to the samples and mixed for 2 min more. Then, the dispersions were left to precipitate for 1.5 h.

After 1.5 hours, the supernatant of each sample was transferred to a new vial.

The parameters indicating the effect of the chemical agents on samples were total suspended solids (TSS, mg/L) and turbidity (FAU), and were measured using Multidirect Spectrophotometer (Lovibond), and by observation of the color change. The results were compared to the control sample of SW - without any chemical influence. The results are summarized in Table 3.

Results

The synthesized hydroxamic acid polymers should maintain the initial properties of the co-polymer. In parallel, due to the ion chelation activity, the pHA should provide coupling capacity for various contaminants found in water. Table 3 shows that polymers WAS590 (SW6, SW7), or pHA (SW2, SW3), did not exhibit high activity when compared to Fe ³⁺ ions (SW1). The latter could reduce the concentration of suspended solids more than 5 times.

FeCb in combination with polymers improved the coagulation ability of polymers. However, Fe ³⁺ -WAS590 (SW8, SW9) did not have a stronger effect than Fe ³⁺ alone. Hence, pHA was more active than WAS590 with or without Fe ³⁺ . At CHA = 100 ppm and in the presence of FeCb (C = 200 ppm), the sample SW5 obtained the greatest decrease in contaminants (6 times less in TSS, > 5 times in turbidity).

WAS590, at different concentrations, with or without Fe ³⁺ , demonstrated similar activity. This showed that its activity was not a function of WAS590 concentration.

Thus, the coagulation systems described in these Examples can be arranged in order of metal ion chelation efficiency as follows:

Fe ³⁺ (200 ppm)-HA(100 ppm) > Fe ³⁺ (200 ppm)-HA(50 ppm) > Fe ³⁺

(200 ppm) > Fe ³⁺ (200 ppm)-WAS590 (50 ppm) ~ Fe ³⁺ (200 ppm)-WAS590 (100 ppm) > HA(100 ppm) > HA(50 ppm) > WAS590 (100 ppm) ~

WAS590 (50 ppm).

Table 3. The summary of coagulation activity tests using FeCb, WAS590 and pHA in different ratios.

Sample FeCb, ppm WAS590, ppm HA, ppm TSS, mg/L τ, FAU

SW - - - 534 665

SW1 200 - - 101 214

SW2 - - 50 431 513

SW3 - - 100 276 339

SW4 200 - 50 97 143

SW5 200 - 100 88 126

SW6 - 50 - 525 656

SW7 - 100 - 528 665

SW8 200 50 - 128 177

SW9 200 100 - 124 170 The influence of WAS 590 contribution on flocculation in the mixtures with HA was also evaluated. The jar tests were conducted in the presence/absence of FeCb (200 ppm) and the ratios of WAS590 : pHA at 1 : 1 , 2 : 1 , 3 : 1 (w/w) (Table 4). The conditions were similar to the jar-tests described above.

Table 4. Summary of coagulation activity tests using FeCb, WAS590, pHA and their mixtures to estimate the influence of WAS590 on coagulation.

Ferric chloride was shown to be the main component in the destabilization process, stimulating fast (10 sec) agglomeration of suspended contaminants in SW. The FeCb-free systems demonstrated poor flocculation abilities. Hence, the coagulant sites serve, as centers for agglomeration when introducing pHA and/or WAS590. Kinetically, the formation of packed cakes occurred faster in the polymer combination(s) with Fe ³⁺ when compared to amorphous and unconsolidated sediments present in the coagulant only sample. Increasing the contribution of WAS590 in the mixtures with pHA decreased the flocculation activities. Such a tendency is evident at 50 and at 100 ppm of WAS590 with HA. The maximal decrease in TSS and turbidity was observed with the Fe ³⁺ (200 ppm)-WAS590(25 ppm)-HA(25 ppm) sample. At higher concentrations, polymers tended to act as stabilizers of disperse system (SW). This conclusion is supported by the parameters of SW treated by individual polymers (SW 2.4-2.7).

The chelation was detected by FTIR and UV-vis spectroscopy. It was shown that chelation of Cu ²⁺ (additional reference ion) and Fe ³⁺ by poly(hydroxamic acid) was greater when compared to the action of the commercial polymer. The chelation formed a 6-member ring, which is the most stable ring.

The combination of Fe ³⁺ with poly(hydroxamic acid) enhanced the coagulation of contaminants dispersed and stabilized in scrubber water. The turbidity decreased more than 5 times, and the concentration of suspended solids was reduced 6 times. This fact can be explained with enhanced ability of the synthesized polymers to induce coagulation. The combination of initial raw polymer with hydroxamic acid and ferric coagulant reduced the suspended pollutants by more than 15 times. The flocculants have a positive economic benefit, because the amount of the fiocculant product used may be reduced without losing flocculation activity. Additionally, the chelation effect may play a significant role in the destabilization process during the scrubber water treatment.

Example 5. Self-polymerization with hypochlorite.

Crosslinking of poly(acrylamide) was conducted as follows. In a typical experiment, linear poly(acrylamide-co- acrylic acid) 1 : 1 ratio (PAA) of medium molecular weight (1 gram dissolved in 100 ml of water) was mixed with 5 ml of 10% w/v hypochlorite in water. The reaction was left to stir at room temperature for one hour where an increase in viscosity of the solution was observed. An increase in molecular weight was determined due to branching and formation of urea bonds. To enhance branching, a small amount of polyethylene imine or chitosan was added to the reaction mixture.