OBTAINING WATER SUITABLE FOR USE IN LAUNDRY

Field of the invention

The present invention relates to a purification composition for the clarification of water from natural sources for laundry purposes. The purification composition comprises both Al-based and Fe-based salts, anionic polyacrylamide and particulate filler. The present invention further relates to a method for clarifying soiled water comprising suspended solids, wherein the purification composition of the invention is applied and to a water clarification kit comprising the purification composition of the invention.

Background of the invention

Water is becoming a more scarcely available commodity, especially in developing countries, where it is not unusual that people have to walk many kilometres to arrive at a natural water source, natural water sources such as lakes, water streams or ground water delivered by water pumps. These natural water sources usually deliver water that is low in organic compounds, but may be soiled, i.e. high in suspended solids, such as clay or ash solids. The suspended solids provide a turbid appearance to the soiled water.

This soiled water is less suitable for laundering fabrics, as it decreases the cleaning efficacy of detergent compositions applied during washing. One way of making water available for laundering fabrics is to clarify the natural source water comprising high levels of suspended solids.

One known method of reducing the suspended solids in water is by using flocculation techniques. Flocculation typically applies the use of sweep flocculation followed by bridging flocculation.

Sweep flocculation encompasses the following: electrolyte flocculants, such as Al- based or Fe-based salts, are added in a sufficient amount so that they form amorphous particles, e.g. amorphous AI(OH)3 particles. These amorphous particles entrap suspended solids leading to clarification of water. Such particles with entrapped suspended solids are called sweep floes and have a size in the range of 100 μηι or below. At this size the sweep floes are still difficult to separate from the water by, e.g. filtration or decantation. Moreover the kinetics of settling down of the sweep floes is very slow.

Therefore the next step is bridging flocculation which encompasses the addition of a polymer flocculant with a molecular weight of at least 100 kDa. These polymers are thought to adsorb on the sweep floes and thereby bring the sweep floes together to form bigger and stronger floes. This phenomenon is known as bridging flocculation. This bridging mechanism helps in increasing the settling velocity of the floes and contributes therefore to faster clarification of water.

Such water purification processes, which apply sweep flocculation, are typically found in the area of industrial waste water purification. Various industries produce waste water, such as chemical manufacturing plants, dairies, canneries, distilleries, paper manufacturing plants, dyeing plants, sewage plants and others. These water purification processes for industrial waste water typically require large water treatment plants and are time-consuming processes.

JP 2007/061718 describes a composite flocculant to remove a dissolved pollutant such as metal ions and a coloring agent such as an ink pigment and to reduce BOD, and which does not need a large amount of an organic polymeric flocculant and is simple in treating sedimented and separated sludge. The composite flocculant contains from more than 60 to 85 wt.% or less of clay and comprises one or more of flocculants selected from an inorganic flocculant and the organic polymeric flocculant wherein the inorganic flocculant contains an iron salt.

WO 2015/062881 describes a composition for purification of water having a compound of Iron and a compound of Aluminium, wherein the ratio of total Iron to total Aluminium is in the range of 1 :0.1 to 1 :150, the basicity of the compound of Aluminium is at least 40%, and the iron compound is a ferric compound in an unhydrolysed state. WO 2015/062881 further describes a packaged water purification product comprising a sachet comprising a first compartment holding the above composition and a second compartment holding a disinfectant.

WO 2008/092724 describes a water purification composition comprising:

i. a coagulating agent which is a water soluble inorganic metal salt having trivalent cation;

ii. a flocculating agent which is a high molecular weight water soluble polymer; iii. an adsorbent which is a water insoluble oxide, hydroxide or oxo-hydroxides of titanium, zirconium, iron, copper or zinc; and,

iv. a biocide which is a halogen compound.

Depending on the origin of the water that needs to be clarified and on the purpose of the water clarification, the clarification method and purification composition need to fulfil different requirements.

To apply electrolyte flocculants in a method for the clarification of water from natural sources for laundry purposes several requirements need to be met. Potential consumers, will only apply such a clarification method, if clarification can be obtained in a few minutes.

An additional requirement for methods for the clarification of natural source water for laundry purposes is that the residual levels of aluminium or iron should be as low as possible in the clarified water. As customers associate too high levels of residual levels of aluminium, especially high levels of polyaluminium chloride, in the clarified water with potential health issues. Further, too high levels of residual iron in the clarified water will lead to discoloration of the fabrics washed with the clarified water.

Potential consumers also have a preference for easy dosing systems, such as that all clarification components are present in one single composition.

A lot of purification compositions in the art for the clarification of water from natural sources for laundry purposes, based on sweep flocculation, are either too slow, not easy to dose or cause too high residual levels of aluminium or iron in the clarified water.

Summary of the invention

The present inventors have found a purification composition for the clarification of water from natural sources for laundry purposes, that overcomes the aforementioned drawbacks of the purification compositions in the prior art. The purification composition according to the present invention is easy to dose for consumers, i.e. only the dosing of one single composition is required.

The residual levels of aluminium and iron remaining in the clarified water, after the application of the purification composition, are well within the ranges that are considered acceptable. Further, the clarification of natural source water, with the purification composition of the invention, is obtained within a few minutes.

More particularly, according to a first aspect the purification composition of the invention relates to a purification composition comprising:

i. 2 to 20 wt.%, calculated by weight of dry matter, of an aluminium chlorohydrate compound, having a basicity in the range of 60% to 85%;

ii. 2 to 20 wt.%, calculated by weight of dry matter, of an iron flocculant;

iii. 0.1 to 5 wt.%, calculated by weight of dry matter, of an anionic polyacrylamide having a molecular weight of more than 100 kDa;

iv. 40 to 96 wt.%, calculated by weight of dry matter, of a particulate filler;

wherein the dry weight ratio of the aluminium chlorohydrate to the iron flocculant lies in the range of 1 :1 to 1 :5.

According to a second aspect the invention further relates to a method for clarifying soiled water comprising suspended solids, said method comprising the steps of:

i. dosing 0.1 to 3 grams of dry matter of a purification composition per liter of soiled water to obtain a mixture of the water and the purification composition;

ii. stirring said mixture to induce the formation of floes; iii. separating the floes from the water to obtain clarified water suitable for use in laundry;

wherein the purification composition is a purification composition according to the first aspect.

According to a third aspect the present invention also pertains to a water clarification kit comprising:

i. a container comprising the purification composition of the first aspect; and, ii. instructions for use instructing users to dose the purification composition to water to obtain water suitable for laundry washing.

Detailed description of the invention A first aspect of the invention relates to a purification composition comprising:

i. 2 to 20 wt.%, calculated by weight of dry matter, of an aluminium chlorohydrate compound, having a basicity in the range of 60% to 85%;

ii. 2 to 20 wt.%, calculated by weight of dry matter, of an iron flocculant;

iii. 0.1 to 5 wt.%, calculated by weight of dry matter, of an anionic polyacrylamide having a molecular weight of more than 100 kDa;

iv. 40 to 96 wt.%, calculated by weight of dry matter, of a particulate filler;

wherein the dry weight ratio of the aluminium chlorohydrate to the iron flocculant lies in the range of 1 :1 to 1 :5. The term 'flocculation' as used herein refers to a process of contact and adhesion whereby the particles of a dispersion form larger-size clusters.

The term "turbidity" as used herein refers to the cloudiness or haziness of a fluid caused by a large number of individual particles.

The unit "NTU" as used herein refers to Nephelometric Turbidity Units (NTU), as measured by the nephelometer, Turbiquant 2100T, manufactured by Merck. The nephelometer is preferably calibrated by using the standard formazin solutions as recommended by the instrument manufacturer. The nephelometer measures the propensity of particles to scatter a light beam focused on them.

The term "basicity" as used herein refers to is defined by the equation: 100% ^* [OH] / (3 ^* [Al]).

The term "aluminium chlorohydrate" as used herein refers to compounds having the general formula (Al _n CI(3n-m)(OH) _m ), wherein the basicity of said compounds are higher than 60%.

The term "polyaluminium chloride" as used herein refers to compounds having the general formula (Al _n CI(3n-m)(OH) _m ), wherein the basicity of said compound is equal to 60% or less. The weight ratio of the aluminium chlorohydrate compound to the iron flocculant in the purification composition of the invention preferably lies in the range of 1 :1.05 to 1 :3.5, more preferably lies in the range of 1 :1 .1 to 1 :2.

The purification composition of the invention preferably comprises 3 to15 wt.%, calculated by weight of dry matter, of aluminium chlorohydrate compound. More preferably, the purification composition comprises 3.5 to 10 wt.%, calculated by weight of dry matter, of aluminium chlorohydrate compound. Most preferably, the purification composition comprises 4 to 6 wt.%, calculated by weight of dry matter, of aluminium chlorohydrate compound.

The aluminium chlorohydrate compound in the purification composition of the invention is preferably selected from aluminium chlorohydrate, aluminium chlorohydrate silicate, aluminium chlorohydrate sulphate and combinations thereof. More preferably, the aluminium chlorohydrate compound is selected from aluminium chlorohydrate, aluminium chlorohydrate sulphate and combinations thereof. Most preferably the aluminium chlorohydrate compound is aluminium chlorohydrate.

The aluminium chlorohydrate compound in the purification composition of the invention preferably has a basicity in the range of 65% to 80%. The purification composition of the invention preferably comprises 3 to 15 wt.%, calculated by weight of dry matter, of iron flocculant. More preferably, the purification composition comprises 3.5 to 10 wt.%, calculated by weight of dry matter, of iron flocculant. Most preferably, the purification composition comprises 4 to 6 wt.%, calculated by weight of dry matter, of iron flocculant.

The iron flocculant in the purification composition of the invention is preferably selected from ferric chloride, ferric sulfate, polyferric flocculant and combinations thereof. More preferably, the iron flocculant is selected from ferric chloride, ferric sulfate and combinations thereof. Most preferably the iron flocculant is ferric sulfate.

The purification composition of the invention preferably comprises 0.5 to 4 wt.%, calculated by weight of dry matter, of the anionic polyacrylamide having a molecular weight of more than 100 kDa. More preferably, the purification composition comprises 1 to 3 wt.%, calculated by weight of dry matter, of the anionic polyacrylamide having a molecular weight of more than 100 kDa.

The molecular weight of the anionic polyacrylamide is preferably in between 100 to 5,000 kDa, more preferably between 250 to 2,000 kDa and most preferably in between 500 to 1 ,000 kDa. The anionic polyacrylamide is preferably water soluble.

The purification composition of the invention preferably comprises 50 to 94 wt.%, calculated by weight of dry matter, of particulate filler. More preferably, the purification composition comprises 60 to 92 wt.%, calculated by weight of dry matter, of particulate filler. Most preferably, the purification composition comprises 70 to 90 wt.%, calculated by weight of dry matter, of particulate filler.

The particulate filler in the purification composition of the invention preferably has a density of at least 1.5 kg/dm ³ . More preferably the density of the particulate filler is between 1.75 to 3.5 kg/dm ³ and most preferably the density of the particulate filler is between 2 to 2.5 kg/dm ³ .

The particulate filler in the purification composition of the invention is preferably selected from feldspar, silica, bentonite, calcite, diatomite and combinations thereof. More preferably the particulate filler is selected from feldspar, bentonite and combinations thereof.

In a preferred embodiment the particulate filler is a combination of feldspar and bentonite, wherein the dry weight ratio of the feldspar to bentonite lies in the range of 5:1 to 1 :5. More preferably, the dry weight ratio of the feldspar to bentonite lies in the range of 3:1 to 1 :3. Most preferably, the dry weight ratio of the feldspar to bentonite lies in the range of 2:1 to 1 :2. The purification composition of the invention preferably has a water content of not more than 15 wt.%. More preferably the purification composition has a water content of not more than 12 wt.% and most preferably the purification composition has a water content within 5 to 10 wt.%. The combination of aluminium chlorohydrate compound, iron flocculant, anionic polyacrylamide and particulate filler in the purification composition of the invention preferably constitutes at least 50 wt.%, more preferably at least 70 wt.%, most preferably at least 90 wt.% of the purification composition, calculated by weight of dry matter.

The purification composition of the invention preferably contains less than 5 wt.%, calculated by weight of dry matter, of alkaline buffering agent selected from calcium oxide, sodium carbonate, sodium bicarbonate, calcium hydroxide, magnesium oxide, magnesium hydroxide and combinations thereof. More preferably, the purification composition contains less than 3 wt.%, calculated by weight of dry matter, of said alkaline buffering agent, even more preferably less than 1 wt.% and most preferably 0%, calculated by weight of dry matter, of said alkaline buffering agent.

The purification composition of the present invention is preferably in particulate form. The purification composition is preferably prepared according to the following steps. Preferably, the individual ingredients are weighed as per the proportion and mixed using an appropriate powder mixing apparatus or equipment, known in the art.

A second aspect of the invention relates to a method for clarifying soiled water comprising suspended solids, said method comprising the steps of: i. dosing 0.1 to 3 grams of dry matter of a purification composition per liter of soiled water to obtain a mixture of the water and the purification composition;

ii. stirring said mixture to induce the formation of floes;

iii. separating the floes from the water to obtain clarified water suitable for use in laundry;

wherein the purification composition is a purification composition as described herein before.

In the method of the invention, the purification composition is preferably dosed at 0.2 to 1.5 grams of dry matter per liter of the soiled water. More preferably, the purification composition is dosed at 0.3 to 1 grams dry matter per liter of the soiled water.

The stirring of the mixture in the method of the invention is preferably performed for at least 5 seconds, more preferably performed for 10 to 60 seconds and most preferably the stirring of the mixture is performed for 15 to 40 seconds. In a preferred

embodiment, different patterns of stirring may be applied, e.g. stirring-pause-stirring or stirring-pause or variations thereof.

The steps (i) to (iii) of the method of the invention are preferably performed within a period of 10 minutes, more preferably within a period of 8 minutes, even more preferably within a period of 5 minutes and most preferably within a period of 4 minutes.

The separation of the floes from the water is preferably performed by filtration, decantation and combinations thereof. More preferably the separation of the floes from the water is performed by filtration.

In the method of the invention, the pH of the soiled water, before dosing of the purification composition, preferably lies within the pH range of 5.5 to 8. More preferably, the pH of the soiled water, before dosing of the purification composition, lies within the pH range of 6 to 7.5. In the method of the invention, the pH of the obtained clarified water preferably lies within the pH range of 5.5 to 8. More preferably, the pH of the obtained clarified water lies within the pH range of 6 to 7.5. In the method of the invention, the biochemical oxygen demand (BOD) of the soiled water during 5 days of incubation at 20°C, before dosing of the purification composition, preferably lies below 100 mg O2 per liter of soiled water.

In the method of the invention, the turbidity of the soiled water, before dosing of the purification composition, is preferably at least 15 NTU. More preferably, the turbidity of the soiled water, before dosing of the purification composition, is at least 30 NTU, most preferably the turbidity is at least 50 NTU.

In the method of the invention, the turbidity of the obtained clarified water is preferably less than 10 NTU. More preferably, the turbidity of the obtained clarified water is less than 9 NTU, most preferably the turbidity of the obtained clarified water is less than 8 NTU.

In the method of the invention, the level of soluble aluminium in the obtained clarified water is preferably less than 200 ppb. More preferably, the level of soluble aluminium in the obtained clarified water is less than 175 ppb, most preferably the level of soluble aluminium in the obtained clarified water is less than 150 ppb.

In the method of the invention, the level of soluble iron in the obtained clarified water is preferably less than 200 ppb. More preferably the level of soluble iron in the obtained clarified water is less than 160 ppb, most preferably the level of soluble iron in the obtained clarified water is less than 120 ppb.

The levels of soluble aluminium and soluble iron are suitably measured by inductively coupled plasma emission spectrometry.

A third aspect of the invention relates to a water clarification kit comprising:

i. a container comprising a purification composition as described herein before; and, ii. instructions for use instructing users to dose the purification composition to water to obtain water suitable for laundry washing.

The water clarification kit of the invention preferably does not comprise an alkaline buffering agent selected from calcium oxide, sodium carbonate, sodium bicarbonate, calcium hydroxide, magnesium oxide, magnesium hydroxide and combinations thereof.

The invention is further illustrated by the following non-limiting examples.

Examples Example 1

Several purification compositions were compared for their clarification effect on soiled water, having a turbidity of about 35 NTU and a French Hardness of 48 °FH.

Model soil was prepared by thoroughly mixing iron(lll)oxide and kaolinite in an equal weight ratio. Water with a hardness of 48 °FH was prepared by adding appropriate amounts of Ca ²⁺ and Mg ²⁺ in a weight ratio 2:1 to the water. Model soiled water was prepared by adding 0.2 g of the model soil per liter of the water with a hardness of 48 °FH. The model soiled water had a pH of 7.2 and a turbidity of 35 NTU.

Different water purification compositions were prepared according to the ingredients displayed in Table 1. Appropriate amounts of each of these components were weighed and mixed to get a uniform composition.

Table 1

1 2 A B C D

Ingredients

(wt.%) (wt.%) (wt.%) (wt.%) (wt.%) (wt.%)

Aluminium chlorohydrate

5 4 4 5 - - with a basicity of 80%

Ferric sulfate 5 6 - - 4 6

Bentonite 48 48 54 53 54 52 Feldspar 40 40 40 40 40 40

Anionic polyacrylamide

2 2 2 2 2 2 (PAM)

Clarification method

0.5 g of a purification composition was added to 1 liter of model soiled water. The mixture of soiled water and purification composition was stirred for 20 seconds, followed by a pause of 20 seconds and subsequently the mixture was stirred again for 20 seconds. The mixture was left to stand for two minutes to allow the settling of the floes. After these two minutes a sample of the obtained clarified water was taken from the top.

The turbidity was measured for each sample using a nephelometer, Turbiquant 2100T, Merck. A final turbidity value of lower than 10 NTU was considered to be acceptable. The results of the turbidity measurements in the different samples are shown in Table 2.

Table 2

^* Obtained floes were too weak

Example 2

A similar experiment as described for Example 1 was performed, except for that the purification compositions as indicated in Table 3 were used to clarify the model soiled water and that the model soiled water had a different water hardness. The hardness of the used model soiled water in this example was 40 °FH.

Table 3

3 E

Ingredients

(wt.%) (wt.%)

Aluminium chlorohydrate

5 5

with a basicity of 80%

Ferric sulfate 5 - Bentonite 48 53

Feldspar 40 40

PAM 2 2

The results of the turbidity measurements in samples 3 and E are shown in Table 4.

Table 4

Example 3

A similar experiment as described for Example 1 was performed, except for that the purification compositions as indicated in Table 5 were used to clarify the model soiled water. Purification composition F was added in an appropriate amount to the model soiled water to keep the concentration of the aluminium chlorohydrate, ferric sulfate and PAM in the model soiled water at the same height as the concentration of these components delivered by purification composition 4 (which was dosed at 0.5 grams per liter model soiled water).

Table 5

The results of the turbidity measurements in samples 4 and F are shown in Table 6. Table 6

Example 4

A similar experiment as described for Example 1 was performed, except for that the purification composition as indicated in Table 7 was used to clarify the model soiled water. Furthermore, in the obtained clarified water the levels of soluble aluminium and soluble iron were measured using ICPES analysis. ICPES stands for inductively coupled plasma emission spectrometry.

Table 7

Water clarification

The model soiled water was treated with the purification composition and stirred as described for Example 1 . The mixture of soiled water and purification composition was then allowed to stand for 2 minutes. After these two minutes, the obtained clarified water was filtered through a cloth filter to remove the floes.

ICPES analysis of soluble aluminium and iron

50 ml of the obtained clarified water was filtered through a 400 micron syringe filter and treated with 2 ml of suprapure nitric acid (70%) to dissolve soluble aluminium and iron present in the clarified water. The water was again filtered through a 400 micron syringe filter and then analysed using ICPES using appropriate aluminium and iron standards. The results of the turbidity measurement and the ICPES analysis are shown in Table 8.

Table 8

Standard deviation is indicated between brackets, measurements were performed in triplicate

Example 5

A composition as indicated in Table 8 was used to clarify the model soiled water.

The model soiled water was treated with the purification composition and stirred as described for Example 1 . The mixture of soiled water and purification composition was then allowed to stand for 2 minutes. After these two minutes, the obtained clarified water was filtered through a cloth filter to remove the floes. Turbidity of the clarified water was measured.

TABLE 8

Formulation based on D1

Final turbidity 76.7 NTU Example 6

Samples of model soiled water were treated with the different purification compositions shown in Table 9 and stirred as described for Example 1. The mixture of soiled water and purification composition was then allowed to stand for 2 minutes.

After these two minutes, the obtained clarified water was filtered through a cloth filter to remove the floes. The clarified water obtained after treatment with each composition (Formulation 1 through Formulation 5) was used to wash different fabrics (cotton, polycotton, and polyester) with 3 g/l Surf excel. After 5 wash cycles yellowing of the fabrics (indicative of high residual iron) was determined (Tablesl O (SRI) and Table 1 1 (b-value). The control comprised of clothes washed with clean water + 3 g/l Surf excel. Higher the b-values, the greater is the yellowing. Smaller the SRI, greater the amount of soil on the fabrics.

TABLE 9

Ingredients Formulation Formulation Formulation Formulation Formulation

1 2 3 4 5

ACH 0.05 0.025 0.5 1.5 1.5

Ferric sulfate 0 0.025 0.1 0.5 1.5

Feldspar 0.25 0.2 0 0 0

Bentonite 0.19 0.24 0.5 0.45 0.45 anionic 0.01 0.01 0.03 0.03 0.03 polyacrylamide

Total 0.5 0.5 1.13 2.48 3.48

ACH/Fe2(S04)3 0.05:0 1 :1 5:1 3:1 1 :1 ratio

Fe/AI ratio 0.00 0.64 0.13 0.21 0.64

Al/Fe ratio #DIV/0! 1.56 7.78 4.67 1.56 Table 10

Table 1 1

Example 7

The compositions (Formulation 1 , 2, and 3) as indicated in Table 12 were used to clarify the model soiled water as well as measure arsenic concentration in the clarified water. The input arsenic concentration of the water to be treated was measured at 300 ppb. Table 12