The present invention concerns the fabrication of plastic materials with film forming properties obtained by using soluble biopolymers (SBP) isolated from residual biomass, fossil source, liquor from cellulose pulp industry, sugars and polysaccharides and their derivatives. Such plastic materials are suitable for the fabrication of packaging items, bags for the collection and transport of wastes, mulch films and green house cover to use in agriculture, as ion exchanging materials, for the fabrication of membranes to be used in separation process of gases or for the selective transportation of ions in solution membranes, and generally for the uses in which commercial polymers from fossil sources are used. Features characterizing the present invention are the following ones:

1. the origin, composition, and fabrication process of the SBP biopolymers and their derivatives;

2. the use of the above biopolymers for the manufacture of plastic materials;

3. the composition of the plastic materials. To appreciate the content of this application, it should be considered that each invention is made by several elements. These elements, taken separately, may be known. However, combined together in concerted fashion may produce novelty. Thus, novelty in the present application lies in the assembly of the above features, not in the individual parts. Indeed, many patents and scientific publications deal with the fabrication of plastic materials suitable for the fabrication of objects to use for packaging and transportation of food products. Such materials are made with synthetic polymers obtained from fossil source and/or biopolymers obtained from dedicated crop such as starch and proteins, or obtained fermentation of sugars under controlled conditions. To the knowledge of the author of the present invention, there are no known plastic materials obtained from compounds isolated from residual biomass or from wastes of renewable materials' industrial processes. Several papers have been published reporting substances that may fall in the category of soluble biopolymers or of biodegradable plastic materials. However, none of these documents describes products having the same chemical composition of organic functional groups and mineral elements, and/or source, and/or fabrication process as the SBP used in the present invention. Also, no published documents describe plastic materials made from the above SBP and/or having the same qualitative and quantitative composition. Processes for the production of water-soluble biopolymers (SBP) from residual biomasses, said SBPs having a defined molecular weight, and mineral and organic compositions, have been disclosed according to WO2013/093951. In this application, the SBPs are obtained by alkaline hydrolysis of residual biomass of urban, agricultural, forest, agro- industrial, animal and industrial origin, or deriving from fossil materials. The same patent application defines also the use of the SBP as auxiliaries for remediation of soil and waters contaminated by undesired organics and metals, as inhibitors of the mineralization of organic N, a binding agent, and as photosensitizers to enhance photosynthesis. The use of the above SBP for the fabrication of plastic materials, as described in the present patent application, is a new surprising discovery, which allows a number of economic and environmental benefits, relatively to the background hereinafter described.

The interest in biomass as renewable energy source for sustainable development stems from the concern of fossil sources depletion and from the need to manage higher and higher amounts of wastes, due to increasing human consumption habits. Since most fossil sources are used as fuel, the exploitation of biomass has been so far conceived solely to produce fuel. Thus, current biomass treatment technology has been developed mainly to perform combustion for the production of thermal and electrical power, chemical reactions to obtain biodiesel, and fermentation to yield biogas and bioethanol. Such technologies are however expensive. They cost more than the market value of the obtained energy or fuel . The reason for this is due to a number of unfavorable features, which are typical of biomass: i.e. high water content, distribution over wide surface areas, low conversion of organic carbon to the desired product and/or no exploitation of the residual unconverted organic fraction. It is commonly agreed that this situation could be improved by developing biorefineries , which were run with the same strategy as oil and carbon refineries: i.e. to valorize all products either in the fuel as well as in the chemicals' market. Supporting this approach, several studies estimate that the sole residual biomass, annually produced worldwide, has a potential energy content, which could virtually be used to replace the current oil consumption. To this scope, one could in principle exploit the potential bioenergy contained in residual biomass from urban, agriculture, forest and animal source, and from industrial processes such as in the wood paper and pulp and food industry.

The sustainable use of such residual biomass depends however either on the biomass nature and on the technology needed for its transformation. Urban biowastes, for instance, are in principle mostly favored as cost effective source. As result of population urbanization and increasing human consumption habits, they are concentrated in confined spaces and have relative high organic carbon content. Agricultural residues, vice versa, are spread over wide surface areas; their viability as energy source varies greatly depending on the geographical location and on the intensity of local agriculture practices. As to technology, the current waste treatment plants comprise facilities for biomass combustion for powerhouses, anaerobic digestors for biogas production, and aerobic digestors for compost production. Incinerators rise public concern for fear of fine dust emission in air, whereas fermentation facilities are more accepted by population. Composting plants however do not allow obtaining a significant revenue, since the product is scarcely marketable. Biogas plant on the contrary produce an easily marketable product. However, the cost of biogas production is higher than its sale value. This situation stems from a number of critical points connected to the efficiency of the fermentation process, leading to no more than 50 % conversion of the potential chemical energy contained in the process biomass feed. Consequently, biogas plants must bear the cost of disposing the unconverted organic residue, conventionally known as the process digestate. Attempts to overcome these critical points are the codigestion of biowastes of different nature and the development of plants performing anaerobic digestion of the biomass input, followed by composting of the digestate. Relatively to sole composting plants, the combined anaerobic/aerobic process produces less biomass volume to dispose. This however keeps the plant cost/revenue ratio still quite high.

It is readily evident from the above background that the future of a biorefinery fed with biowastes depends not only from the developing low cost processes yielding added value products, but also from the size and value of the market where these products should be allocated. In this context, WO2013/093951 had indicated a number of uses for the SBP in the remediation of polluted soil and waters, in anaerobic digestion, in the formulation of binding agents, and in agriculture. The present application discloses now a great opportunity to valorize the SBP in a wider market, specifically the plastics' markets.

Materials made from biopolymers or mixes of biopolymers and synthetic polymers have been made in the last few years with the intent to replace synthetic polymers. This would allow reducing the consumption and environmental impact of synthetic polymers derived from fossil sources and, at the same time, to manufacture more ecofriendly materials. The SBP features described in the previous application WO2013/093951 , i.e. their polymeric nature and the property to increase plant productivity by enhancing photosynthesis, suggested that these products could be also used for the preparation of self- fertilizing mulch films. While playing their role of covering and protecting cultivated soil, they would release the SBO in the soil over their required service life and allow positive agronomic effects at the same time. Similarly, they could allow the manufacture of several plastic products for daily consumers' use, which were environmentally friendly. This prospected the SBP allocation in the bioplastic market. The perspective was rather appealing since bioplastics currently cover only a small portion (under 1%) of the total plastics market, and their use is expected to grow. Thus, they have large opportunities for higher market share in the future.

Bioplastics are currently made from two types of polymers; i.e. biopolymers obtained by fermentation of sugars under controlled conditions, and natural polymers such as starch or lignocellulosic materials obtained from dedicated crops. Plastic materials containing biopolymers similar to the above SBP, having the molecular weight, mineral and organics composition, and isolated from the sources described in previous application WO2013/093951, are not know yet.

The main commercial bioplastics, produced by extrusion or blown film technology, contain starch obtained from dedicated crop, such as the products by Rodenburg Biopolymers (NE) , Novamont SPA (I) , Biotec GmbH (DE) , or cellulose acetate obtained from cellulose isolated from wood, such as the product by Innovia Films (GB) , and biopolymers obtained from the fermentation of starch and sugars, such as polyhydroxyalcanoates by Kaneka (USA) and polylactic acid by Nature Works PLA (USA) . Plastic materials are part of human daily life. According to the 2009 EU plastic report the 2008 European plastics demand has 48.5 million tons, mainly polyethylene, polypropylene, polyvinyl chloride, polystyrene, and polyethylene- terephtalate, with a 9 % yearly increase forecast. The need to reduce the use of fossil sources and the consequent carbon dioxide emission have promoted the use of bioplastics. Although in principle more acceptable by the environment, these materials must however compete with the polymers from fossil sources for mechanical properties. Also, the use of dedicated crops for the production of bioplastics is criticized. According to FAO, the world index of primary food products has reached a peak of 214.7 in December 2010, higher than that of 213.5 reached during the food crisis of 2008. Under these circumstances, the increasing use of starch and sugar from dedicated crops is a further threat for the food market. It is therefore imperative, for producing fuel and chemicals, to develop processes for the exploitation of biomass not used for food production. Thus, residual biomass is bound to be the acceptable favored source of energy and chemicals in the future.

The above state of art has offered worthwhile scope for developing new cost effective processes, products and materials from residual biomass, specifically soluble biopolymers to use in place of current chemicals obtained from oil and coal. According to the present invention, this scope is achieved by the procedure and claims reported hereinafter, all of which are comprised in the present invention. More specifically, the objectives of the invention are: (i) to widen the fields of applications of SBP ; (ii) thus, to develop new processes to obtain SBP with improved properties, either by treating biowastes of urban, agricultural, forest, agro- industrial, animal and industrial origin, or fossil materials, or by reacting further the SBP to yield more hydrophilic products with higher content of carboxylic functional groups and/or sulphonated biopolymers ( SSBP ) ; (iii) to obtain plastic materials in film or other forms using the above SBP and SSBP , and lignosulphonates ( LS ) from the pulp and paper production processes .

According to the present invention, plastic materials are obtained by mixing the above SBP, SSBP and LS , and/or their mixture with synthetic polymers such as, but not exclusively, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyethylene-terephtalate, and other polymers containing functional groups such as COOH , OH , NH ₂ , CONH, COOR, where R = alkyl or aryl, as for example in co-polyethylene-polyvinyl alcohol (PETPVA) , co-polyesters, polylactons, polyamides, polyamines, polyacrylic acid and polyalcohols . To this purpose, the SBP are obtained by alkaline hydrolysis and/or ozonization of a residual biomass or a fossil material such as coal of different ages, for example peat or lignite, containing organic matter. The SBP production process comprises the following steps:

1. to acquire biowastes of urban, agricultural, forest, agro- industrial , animal and industrial origin, or coal of different ages, such as peat or lignite;

to treat the biomass of step 1 with acid and/or alkali at variable pH comprised between 2 and 13, liquid/solid ratio from 1 to 4, in the presence or absence of ozone, at room temperature or heating up to 220 °C for 2 minutes up to 4 hours at atmospheric pressure or in closed vessel under autogenous pressure, wherein the heating is provided by conventional heat exchange with a hot fluid, or electrically or by microwave, to obtain a solid insoluble residue (SIR) and a liquid phase;

to separate the liquid phase of step 2 by the following procedures, eventually carried out in combined sequence :

i. changing the pH resulting from step 2 to obtain a precipitate and a liquid phase, wherein the precipitate contains the higher molecular weight SBP (HMW-SBP) in solid form, and the liquid phase contains lower molecular weight soluble bio- organic products (LMW-SBP) ;

ii. membrane filtration to yield a retentate and a permeate, wherein the retentate contains the HMW- SBP in solution or in gel form, and the permeate contains the LMW-SBP

iii. drying the liquid phase obtained in step 2 or the solid and liquid phases obtained in the above (3i) and (3ii) steps;

4. to treat the recovered SIR, repeatedly by the procedure outlined in steps 2-3, in order to maximize the yield of HMW- and LMW-SBP.

The SBP can be then used as such or reacted further to yield products with higher content of carboxylic acids or the sulphonated derivatives SSBP. In the former case, the SBP are treated with ozone in solution. In this reaction, the SBP starting concentration, ozone flow rate, pH and gas-liquid contact time are optimized to bleach the solution, increase the number of COOH functional groups in the final product to the desired value, and minimize the mineralization of organic C. The SSBP are obtained by sulphonation of the SBP with common sulphonating agents according to the best organic chemistry practices.

Plastic materials are obtained by solvent casting or extrusion of mixtures of the above SBP, SSBP, and LS with the synthetic polymers.

The present description demonstrates that biopolymers having different molecular weight and composition, such as SBP and SSBP, isolated form residual biowastes of different source, their sulphonated derivates, and the lignosulphonates obtained from the pulp and paper industry, can be obtained to make plastic materials. Upon properly adjusting the relative biopolymers-synthetic polymer composition, such plastic materials, compared to the commercial plastic materials made materials, compared to the commercial plastic materials made entirely from polymers obtained from chemicals deriving from fossil sources, have the following advantages: higher molecular weight, higher Young's modulus, higher tensile strength, lower cost and higher environmental compatibility. Relative to the plastic materials containing biopolymers obtained from dedicated crop, the plastic materials containing the waste derived SBP have the advantage of not producing any negative impact on the availability and cost of food products, while contributing to alleviate society the economic burden deriving from the management of biowastes, particularly those of urban and agriculture source.

With respect to the features characterizing the present invention, which have been listed above in the introduction sentences of the present description, it should be considered that these features, considered all together, and not separately, constitute the novelty of the present invention with respect to the state of art. In more details, the SBP products are composed from an organic and a mineral fraction. The organic fraction is a mixture of molecules with 1-500 kDalton molecular weight ^" and 1-53 polydispersivity index. Such polymeric molecules are characterized by the presence of aliphatic carbon chains, aromatic carbon, and polar functional groups, free and/or bonded to the above reported mineral elements, to yield the following % weight relative chemical composition: 37 < C ≤ 65; 3 < N < 7; ash < 30; Si ≤ 3.0; Fe < Ni < 0.01; Zn < 0.05; Cr < 0.003; Pb < 0.01. In the above composition, N e C mean organic nitrogen and organic carbon distributed over the above described carbon types and functional groups with the following composition expressed as mole fraction of the specific carbon type over the product total organic: 0.1 ≤ Cal ≤ 0.6; CN < 0.1; OMe < 0.1; 0.1 < OR < 0.6; 0.02 < 0C0 < 0.15; Ph < 0.30; PhOH < 0.06; PhOR/Ar < 0.09; 0.04 < COOH < 0.30; CON < 0.12; C=0 < 0.05, where Cal = aliphatic C bonded to H and/or to other aliphatic C and/or to aromatic C, CN = C bonded to amino functional groups, OMe = metoxy C; OR = alcoxy C, OCO = anomeric C, Ph = aromatic C bonded to H and/or to other aromatic C and/or to other aliphatic C, PhOH = phenol C, PhOR/Ar = phenoxy C, COOH = carboxylic C, CON = amide C, C=0 = keto C.

The SBP are isolated from residual biomass of urban, agriculture, forest, agricultural- industrial , animal (as for instance manure) and industrial source, such as for example, lignin and polysaccharide material contained in the liquor of the cellulose pulp process, in the wastes of the wood processing industry, of the food industry, of slaughter houses, in sewage sludge. The SBP can also be obtained from fossils such as peat, lignite, leonardite.

From all above sources, the SBP can be obtained using several process, separately or combined, hereinafter named hydrolysis/ozonization/precipitation separation process (SP) , and hydrolysis/ozonization/membrane separation process (MS) . Each process comprises two phases, hereinafter named hydrolysis, in the presence or absence of ozone, i.e. the reaction with water and/or ozone, and the product separation; the two processes differ one from the other in the separation phase .

In the hydrolysis phase, the above specified residual biomass (RBM) or fossil material is treated with water at 2-13 pH for 4 minutes to 4 hours with a liquid/solid ratio comprised between 8 and 1 and at temperature comprised between room temperature and 200 °C. If a product with enhanced COOH content and reduced color is desired, ozone may be flown through the solid liquid phase. At the end, the settled solid phase containing the solid insoluble residue (SIR) is separated from the surnatant liquid phase containing the soluble organic substances (SOS) produced by the RBM hydrolysis .

The SOS separation is performed by one or both the SP or MS processes. In the SP process, the SOS phase is acidified to pH < 4 in order to precipitate the SBP products. These are recovered in solid form by centrifugation and/or filtration, followed by washing and drying. In the MS process, the SOS phase is pumped through a microfiltration (MF) , ultrafiltration (UF) , nanofiltration (NF) or dialysis membrane unit to yield a retentate (RF) and a permeate (PF) phase. The RF phase contains the SBP in solution or gel form up to 17 % concentration and the desired pH, without need of adding other reagents to correct pH to the desired value. The RF may be used as such or after drying to produce solid SBP. The PF phase is recycled to the hydrolysis/ozonization reactor to perform the reaction for the next RBM lot. In this fashion, upon increasing the number of reaction/separation/re cycling operations, the PF is enriched until saturation with organics having molecular weight below 5 kD. When the organics concentration is near the solubility value, the PF phase is dialyzed to yield water to recycle to the hydrolysis reactor and a concentrated solution of organics. This latter, after water evaporation, yields a residue containing organics with molecular weight below 5 kD.

When analyzed, the SBP products obtained as above have 25 % ash content, due to the presence of the mineral elements. The following procedure yields SBP with reduced mineral content. By changing the pH of the above RF or drying it a precipitate is obtained. This is separated from the mother solution by centrifugation and/or filtration, washed repeatedly with HC1 or HF solution and dried. The reduced mineral content occurs due to the following reactions:

RCOOM + HX = RCOOH + MX (1)

PhOM + HX = PhOH + MX (2)

CNDDDM + HX = CN + MX + H+ (3) ,

where M is the mineral element, HX is the mineral acid, RCOOM, PhOM e CNDDDM are the carboxylic, phenol and amino groups holding M with ionic and donor-acceptor bonds, RCOOH, PhOH e CNDDDM are the corresponding metal free organic functional groups. The products containing the metal free functional groups are insoluble in water. This property allows to separate easily the mineral elements (M) in water soluble form as chlorides (X = CI) or fluorides (X = F) .

Oxidized SBP with higher content of acid functions and lighter color can be obtained by further treating the SBP in water solution with ozone under experimental conditions to be optimized in each case depending on the type of SBP, and the desired product color and oxidation degree.

Sulphonated derivatives (SSBP) are obtained by reacting SBP, or their sourcing materials, with concentrated sulphuric acid, oleum, liquid sulphur trioxide or complexes of sulfur trioxide with electron donor molecules such as dioxane, dimethylsulphoxide, and with sodium sulfite at 2.5-11 pH and 25 e 200 °C, eventually in closed vessel under autogenous pressure. The reaction products are isolated as reported in the example section.

The above SBP, and/or their oxidized and/or sulphonated derivatives, and or the lignosulphonates (LS) , mixed with synthetic polymers from fossil source yield plastic materials. The synthetic polymers to use are polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyethylene-terephtalate, and other polymers containing functional groups such as COOH, OH, NH ₂ , CO H, COOR, where R = alkyl or aryl, as for example in co-polyethylene-polyvinyl alcohol (PETPVA) , co-polyesters, polylactons, polyamides, polyamines , polyacrylic acid and polyalcohols . These polymers include either current commercial products and others that may be synthesized in the future, provided that they contained similar C types and functional groups as those listed above. The fabrication of the plastic materials is achieved by solvent casting or extrusion. In the first case, the biopolymer-synthetic polymer mix is made by disoolving the synthetic polymer into an organic solvent such as dimethylsulphoxide, dioxane, alcohol, N methyl pyrrolydone, or other, in which the polymer is best soluble. A water solution is also prepared containing the SBP and/or SSBP and/or LS at the pH at which the biopolymer is best soluble . This water solution is then added to the solution containing the synthetic polymers. The mixed solvent liquid phase is distilled to eliminate the solvent boiling at lower temperature until an homogeneous liquid phase is obtained. This liquid phase is deposited over a metal sheet, preferably stainless steel. The metal sheet is heated to 105 °C until one obtains a film that is easily detachable in free standing form by immersion in water. The procedure by extrusion comprises feeding the biopolymer-synthetic polymer mix to an extruder, operating with a temperature profile between 60 and 180 °C. In this case, plasticizers are eventually added, such as glycols, polygycols, diols and polyols, in a sufficient amount to obtain a paste and favor the formation of H-bonds or condensation reactions between functional groups of the biopolymer and the synthetic polymer. The temperature profile of the extruder is optimized to allow evaporation of solvents with boiling point over 100 °C and so to obtain a final homogenous product which, by mmersion in water, will release the minimum amount of water soluble polymer. The plastic materials obtained as above can be bent at 180 degrees angle without breaking.

Plastic materials containing the biopolymer and the synthetic polymer up to 1 biopolymer/synthetic polymer ratio may be obtained in this fashion. Once becoming a component of the plastic material, the biopolymer loses its water solubility property and becomes soluble in the same solvent of the synthetic polymer. Generally the Young's modulus and tensile strength of the material increase upon increasing the concentration of biopolymer up to about 20 %, and then decrease for higher concentration. In the following section with Examples, a specific example of a material containing 20 % SBP and 80 % PVAPE is described which illustrates further details on the fabrication and characterization of the composite plastic materials containing SBP biopolymers and synthetic polymers.

Hereinafter, several examples are reported to provide details of the present invention and help a full comprehension of its different aspects. The specific examples however are not meant to be limitative of the invention as, according to its principles and guidelines, it may be put into practice by a combination of procedures, components, materials, and other experimental details which will allow the expert chemist and/or potential user to optimize processes' and products' performance. In the following description, reference to a specific form of use or application of the invention means that the reported details are only one of the many ways to apply the present invention. Thus, different ways to apply the present invention are reported hereinafter. Furthermore, the experimental features of single application forms may be combined in several ways with specific details reported for other applications to optimize the realization of the present invention for the intended application. Examples are hereinafter entitled in different ways. Titles must not be taken as limitative of the invention. They are used only for the purpose of summarizing the specific content of the described example.

Examples

Process to obtain SBP by alkaline hydrolysis and membrane separation.

In a reactor equipped with mechanical stirrer and facilities for heating by diathermic fluid circulation or electrical coil, one part in weight of residual biomass (RBM) , of urban, agriculture, agricultural- industrial source, or from effluents of wood processing, and of the above listed fossil materials, such as for instance compost obtained from the organic humid fraction of urban refuse, is treated with 4 parts in weight of pH 13 water containing NaOH or KOH, at 65 °C for 4 hours under stirring. At the end, stirring is stopped, and the solid/liquid suspension is allowed to settle until the surnatant liquid phase flows easily through a 0.125 mm sieve. This allows to separate and collect about 70 % of the starting liquid volume. The collected liquid phase contains the water soluble organic substances (SOS) , produced by hydrolyzing the starting RBM.

The residual liquid phase, about 30 % of the starting alkaline water, is retained by the solid phase settled in sludge consistency. This material contains the solid insoluble residue (SIR) , and part of the soluble organics contained in the water phase retained by the settled SIR.

The sludge is washed with a volume of fresh water equal to 30 % of the starting volume of alkaline water before the hydrolysis, in order to displace the soluble organics phase retained by the SIR phase. During this operation, the resulting solid/liquid suspension is kept under stirring at room temperature for 1 hour, and afterwards it is allowed to settle for 1 hour. The surnatant liquid phase is withdrawn from the reactor and added to the hydrolyzate first removed from the reactor. The total collected liquid contains SOS at 3 % concentration and pH 10. This liquid is conveyed to the ultrafiltration membrane having 5 kD cut off. The membrane inlet and outlet pressure values are 4 and 2 bar respectively. This allows to obtain a retentate (RUF) volume equal to 25 % of the inlet volume. By repeating this operation, eventually adding water to the retentate withdrawn from the membrane unit, and/or increasing the pressure gradient through the membrane, the soluble organics phase pH may be lowered and the organics concentration in the retentate enhanced up to 17 % by weight .

The permeate (PUF) , having 11 pH, contains 0,5 %, or less, of water soluble organics with molecular weight below 5 kDalton.

On the contrary, the RUF contains the soluble organics with molecular weight above 5 kD. These products have relative chemical composition within the ranges above specified (see text above) .

The RUF may be dried to yield SBP in solid form or used as such depending on the product intended successive use. The PUF is recycled to the hydrolysis reactor to wash SIR, or to repeat the hydrolytic treatment on the same SIR, or to perform the hydrolysis of a new RBM lot.

The hydrolysis may be carried out at various pH values comprised between 9 and 13. However, SBP yields will decrease at lower pH. Furthermore, depending on the RBM nature, in order to increase the product yield, it may be necessary to increase the reaction temperature up to 200 °C, working under autogenous pressure as required by the reaction temperature. Process to obtain SBP by ozonization and membrane separation. In the same reactor described in the above example, the residual biomass (RBM) , of urban, agriculture, agricultural- industrial source, or from effluents of wood processing, and of the above listed fossil materials, such as for instance compost obtained from the organic humid fraction of urban refuse, is pre-acidified to pH 2.5 using 4N HCl at a solid concentration (consistency) of 1-2% then centrifuged to a consistency of 35-40%. Ozone was then led into the reactor at 0.1-0.8 %, expressed in mass of ozone as a percentage of the mass of the solid phase. At the end of the reaction, the slurry was diluted with water at 1:4 solid/liquid ratio, added with alkali to pH 13 processed further as in the above example of the process to obtain SBP by alkaline hydrolysis and membrane separation.

Characterization of SBP.

The mineral elements concentration of SBP are obtained after mineralization of the sample with HN03-HF at 1:3 in v/v ratio and analyzed by atomic absorption spectroscopy. The C and N concentration are obtained with C. Erba NA-2100 type microanalyzer .

The content of carboxylic and phenol groups is determined by potentiometric titration as follows. Deionized water is boiled under nitrogen flux to remove dissolved carbon dioxide. This water is used for sample preparation. The SBP sample is dissolved at 0,6 g L-l concentration in 1 N KOH. The pH DD13 resulting solution is titrated with IN HCl. A similar titration is performed on a blank sample, which does not contain any SBP, but contains the same alkali amount as the SBP sample. The titration is performed with an automatic instrument such as the Cryson Compact having a resolution of 1 μΐ titrant. In this condition, one obtains pH vs. titrant volume curves showing two inflection points. The COOH e PhOH concentration is calculated from these curves according to Graam method (Brunelot e coll., Chemosphere 1989, 19, 1413- 1419) .

The determination of the concentration of C types and functional groups is performed as follows. Solid-state 13C- MR spectra are acquired at 67.9 MHz on a JEOL GSE 270 spectrometer equipped with a Doty probe. The cross- polarization magic angle spinning (CPMAS) technique is employed and for each spectrum about 104 free induction decays is accumulated. The pulse repetition rate is set at 0.5 s, the contact time at 1 ms, the sweep width is 35 KHz and MAS is performed at 5 kHz. Under these conditions, the MR technique provides quantitative integration values in the different spectral regions. Signals in the 13C NMR spectra are identified based on chemical shift referred to tetramethylsilane. Signals' assignment as a function of the resonance range are: 0-53 ppm aliphatic C, 53-63 ppm O-Me or N-alkyl C, 63-95 ppm O-alkyl C, 95-110 ppm di-O-alkyl C, 110- 140 aromatic C, 140-160 ppm phenol or phenyl ether C, 160-185 carboxyl C, 185-215 keto C. Signals' band areas are measured and assumed to correspond to the relative mole/mole concentration of the above identified functional groups. Further breakdown of concentration of C types and functional groups is obtained according to the assumption underlying the following equations: PhOR = PhO - PhOH (1), CON = COX - COOH (2) , N-alkyl = N - CON (3) , where PhOR and COX are determined from 13C NMR spectra, PhOH and COOH by potentiometric titration and N is the total nitrogen content by microanalysis .

Molecular weight measurements are performed on SBP solutions by "size exclusion chromatography (SEC) " coupled to on line "multi-angle light scattering (MALS) " .

By these procedures the SBP were found to have molecular weight and mineral and organic composition in the ranges reported above (see text of the description of the invention) , depending on the type of biomass and on the reaction conditions. Relatively to the hydrolysis of biomass performed at acid or alkaline pH, the hydrolysis performed after pre- treating the biomass with ozone yields higher conversion of biomass to soluble products, having higher content of acid functional groups and lighter color.

Process to obtain SSBP.

A sample of compost (600 g) obtained from a mix of home and public gardening urban residues and digestate recovered from the anaerobic fermentation of the urban organic humid fraction, containing 44,6% H ₂ 0, 26,61% volatile solids e 28,79% ash, is reacted with con 3 liters of 0.64 M sodium sulfite water solution at 100 °C for 4 hours. At the end of the reaction the solution is centrifuged to separate the solid insoluble residue (SIR) from the water phase containing the soluble organics. The water phase is acidified with HCl fino a pH < 1,5 and heated at to eliminate SO2 from the unreacted sulfite. The solution is then centrifuged to separate the insoluble product (SSBP1) at acid pH. This is then dried at 105 °C. The product yield is 40 g. It contains 5.5% sulfur, corresponding to 1.7 meq/g of sulphonic functional groups. The potentiometric titration of the product gave concentration values of 3.0 e 1.7 meq/g for COOH and PhOH functional groups respectively. The separated acid liquid phase is fed to a Dowex ion exchange column in acid form. The recovered column eluate is evaporated at 60 °C under vacuum to recover a solid product (SSBP2) . This is dried at 105°C. This product (45 g) contains 13% sulfur, corresponding to 4.2 meq/g of sulphonic acid functional groups. The COOH and PhOH groups, determined by potentiometric titration, are 1.3 ed 1.1 meq/g respectively. Thus, the reaction yields two fractions of sulphonated biopolymers, one (SSBP1) insoluble acid pH and the other (SSBP2) soluble at all pH values. These two products are characterized by the different contents of acid groups. Fabrication of plastic films of PETPVA-SBP by solvent casting. A dimethylsulfoxide (DMSO) solution containing 20 % co- polyethylene-polyvinyl alcohol (PETPVA) having 0.6 ethylene repeating units per vinyl alcohol unit and a water solution containing 5 % SBP are prepared separately. The water solution is added drop-wise to the DMSO solution at 105 °C, to allow water evaporation during its addition. When almost all water is evaporated, the remaining DMSO solution is homogenous. An aliquot of this solution is transferred to a stainless steel plate heated at 100 °C until a thin residue in film form is obtained. The plate is kept at 100 °C for 24 more hours. The plate is then immersed in a water bath for at least 1 hour to allow the film detachment from the plate. The recovered free standing film is washed repeatedly with water to remove the DMSO solvent and the unreacted SBP. The absence of free unreacted SBO in the composite film is judged from the absence of color and from the almost neutral pH of the final water washings. Films of different thickness are obtained depending on the concentration and amount of the DMSO solution deposited on the metal plate for solvent evaporation. Films with different PETPVA/SBO ratio are obtained depending on the relative amounts of the two components mixed together. The film product is analyzed for the content of C, N and COOH, and for molecular weight, by the same procedures described for the analyses performed on the neat SBP samples (see characterization of SBP above) . The concentration of SBP in the film is calculated based on the C, N and COOH content found in the film, compared to the C, N and COOK found in the neat SBP. The films are characterized also for their thermal and mechanical properties. Compared to neat PVAPE, the composite PVAPE-SBP films did not differ much for melting temperature, but had lower crystallization and higher glass transition temperatures upon increasing the SBP content. The stress- strain curves demonstrate that the presence of SBP up to about 20 % enhances the Young's modulus, increases the tensile strength, but lowers the strain at break. Table 1 reports typical data obtained for 150 mm films of neat PVAPE and PVAPE containing 20%SBP, wherein the SBP is characterized by the 300 kD weight average molecular weight and by the following C types and functional groups chemical composition relative to total organic C: Cal 0.50, CN 0.1, OR 0.1, OCO 0.03, Ph 0.07, PhOH 0.02, PhOR/Ar 0.01, COOH 0.07, CON 0.09; C=0 0.01. The high differences in molecular weight and mechanical behavior shown between the two films demonstrates that a significant interaction occurs between the synthetic PVAPE polymer and the SBP biopolymer. This interaction is likely to involve the formation of new covalent chemical bonds by a possible condensation reaction occurring between the functional groups of the synthetic copolymer and the biopolymer. This may explain the change of the solubility properties of the SBP biopolymer. Indeed, neat SBP is soluble in water, but not in DMSO. On the contrary, SBP in the composite film becomes soluble in DMSO and insoluble in water. Table 1. Data for PVAPE and PVAPE-8 % SBP films

Fabrication of plastic films of PETPVA-SBP by extrusion.

SBP (34 %) , PETPVA (52 %) , water (14 %) are fed to a twin screw extruder operating at 300 rpm with 60-180 °C temperature profile. The product is pelletized and the pellets are preconditioned 60 ore in a desiccator over saturated lithium chloride to guarantee a water content of 15% in the pellet. The pellets are then processed by a Ghioldi machine, D = 40 mm, L/D = 30, operating at 40-60 rpm between 70 e 200 °C. The product obtained in film form is washed repeatedly with water, to eliminate soluble material, and then dried at 105 °C over P205. The product, characterized as reported above, shows similar properties-composition relationships as the films obtained by solvent casting.

It should be clearly realize at this point that the present invention comprises a wide variety of materials, whose composition depends on the type of synthetic polymer and of the SBP or SSBP used. Following the guidelines given in the present application and the examples describe, the expert in the field will be able to optimize products chemical composition and properties according to the intended uses.

The present invention is not only limited to the fabrication of the plastic materials, but comprises also the water soluble biopolymers for use in the fabrication of the composite plastic materials. These products contain an organic and a mineral fraction. The former contains polymeric molecules with 1-500 kDA molecular weight and 1-53 polydispersivity index, wherein the organic fraction contains 37-65 w/w % C and 3-7 w/w % N relative to dry matter, with N e C being organic carbon and N distributed over several C types and functional groups having the following composition expressed in mol fraction relative to total organic C moles: 0.1 < Cal < 0.6; CN ≤ 0.1; OMe < 0.1; 0.1 < OR < 0.6; 0.02 < OCO < 0.15; Ph < 0.30; PhOH < 0.06; PhOR/Ar < 0.09; 0.04 < COOH < 0.30; CON < 0.12; C=0 < 0.05, where Cal = aliphatic C bonded to H and/or to other aliphatic C and/or to aromatic C, CN = C bonded to amino functional groups, OMe = metoxy C; OR = alcoxy C, OCO = anomeric C, Ph = aromatic C bonded to H and/or to other aromatic C and/or to other aliphatic C, PhOH = phenol C, PhOR/Ar = phenoxy C, COOH = carboxylic C, CON = amide C, C=0 = keto C. The mineral fraction has the following composition expressed in w/w % relative to dry matter: ash ≤ 30; Si < 3.0; Fe ≤ 0.9; Al < 0,8; Mg < 1.2; Ca < 6.5; K < 10; Na < 10; Cu ≤ 0.03; Ni < 0.01; Zn < 0.05; Cr < 0.003; Pb < 0.01. The peculiarity of the above polymers lies therefore in the presence of both organic and mineral components, the former being bonded to .the mineral components, both having a synergic role. In essence, the organic components keep in solution the mineral components, and the latter ones in turn modulate the properties and behavior of the organic components .

The invention comprises also a procedure to obtain the above water-soluble biopolymers mix by hydrolysis, eventually coupled to ozonization according to the following steps:

acquiring a biomass of urban, agriculture, agricultural-industrial source, or from effluents of wood processing, or a fossil material such as peat and lignite;

- hydrolyzing the biomass or the above fossil materials at acid or alkaline pH, eventually in the presence of ozone, or after pretreating the biomass or fossil material with ozone, to yield a solid insoluble residue and a liquid phase, wherein the two phases contain biopolymers with different molecular weight;

separating the liquid phase by precipitation at acid pH to obtain a liquid phase and a precipitate;

- alternatively filtering the liquid phase by mean of a membrane of different porosity to yield a retentate and a permeate, wherein the retentate and permeate contain biopolymers with different molecular weight;

- drying all above phases to obtain solid products; eventually treating the solid products with HC1 and HF to obtain biopolymers with reduced ash content. By the presence of both the organic and mineral components, and of its variable composition depending on the type and processing of the sourcing material, the biopolymers mix can be used in many fields according to a variety of processes, some of which are exemplified as follows:

a) process for the remediation soil containing organic or mineral pollutants comprising the following steps:

- preparing a biopolymers water solution;

washing the contaminated soil with the biopolymers solution;

separating the soil from the washing solution, wherein the washing solution contains the soil pollutants bonded to the biopolymers;

- precipitating the pollutants bonded to the biopolymers at acid pH, or

filtering the pollutants bonded to the biopolymers through a membrane with a cut off ≤ 5 kD;

burning the precipitated materials or dry and burn the membrane retentate containing the pollutants bonded to the biopolymers .

b) process for the remediation of and/or abatement of COD in water polluted by organics and metals, comprising the following steps: - preparing a biopolymers water solution;

adding the biopolymers solution to the polluted water;

- precipitating the pollutants bonded to the biopolymers at acid pH, or

- filtering the pollutants bonded to the biopolymers through a membrane with a cut off ≤ 5 kD;

burning the precipitated materials or dry and burn the membrane retentate containing the pollutants bonded to the biopolymers

c) process to inhibit the mineralization of organic N during anaerobic fermentation of biomass:

adding the biopolymers to the fermentation liquor containing the organic substrate;

carrying on the anaerobic fermentation to obtain a digestate with low ammonia content.

The invention therefore concerns also the use of the biopolymers for the remediation of polluted soil and water, and for controlling anaerobic digestion processes in vitro and in vivo during animal digestion, in order to reduce ammonia emission and/or a greater utilization of protein by the animal metabolism.

Other uses of biopolymers are the following:

- in agriculture to promote photosynthesis and biomass growth due to the capacity of the biopolymers to complex and keep iron in solution at soil pH. - in the manufacture obj ects and article requiring a binding agents containing organic component or a mineral component .