EP1778378A1

EP1778378A1 - Use of optionally modified and optionally insoluble starch for eliminating natural organic substances in liquids

Info

Publication number: EP1778378A1
Application number: EP05783843A
Authority: EP
Inventors: Caroline Mabille; Jean-François SASSI; Vincent Monin; Yves Mottot
Original assignee: Rhodia UK Ltd
Current assignee: Solvay Solutions UK Ltd
Priority date: 2004-06-29
Filing date: 2005-06-28
Publication date: 2007-05-02
Also published as: FR2872063A1; WO2006010849A1; US20090084730A1; US8097165B2; FR2872063B1

Abstract

The invention concerns use of modified and insoluble starch for eliminating natural organic substances in liquids and in particular in liquids used for food such as drinking water, beverages, fruit juices or syrups, as well as natural water, industrial process water, or wastewater.

Description

USE OF AMIDON POSSIBLY MODIFIED AND

POSSIBLY INSOLUBLE FOR ELIMINATION

NATURAL ORGANIC SUBSTANCES IN LIQUIDS

The invention relates to a use of modified and insoluble starch for the removal of natural organic substances in liquids and in particular liquids for food purposes such as drinking water, drinks, fruit juices or syrups, and also natural waters, industrial waters, or wastewater.

Natural organic matter in water can cause many problems. They are responsible for the degradation of the organoleptic properties of drinking water, that is to say the taste, the color, or the smell of water. They can cause bacterial reviviscence or generate potentially toxic disinfection byproducts.

The elimination of natural organic matter present in water is therefore an essential objective to ensure the quality of drinking water produced from natural waters. In France, Decree No. 2001-1220 of 20 December 2001 sets the quality standard for total organic carbon (TOC) of water intended for human consumption at a level of 2.0 mg / l.

Moreover, natural organic substances present in beverages or in liquid food compositions such as syrups can modify their properties, in particular their appearance (haze, coloration). That is why it is also important to find a way to eliminate these natural organic substances that is compatible with food regulations.

On the other hand it may be necessary to treat industrial water and especially water from the food industry or waste water rich in natural organic materials before discharging into the wild to avoid pollution.

Finally it may also be necessary to treat natural waters rich in organic substances to make water for industrial use. It can be mentioned in particular the production of water for the food industry, pharmacy or electronics.

Until now it was known to use activated carbon, ion exchange resins or cationic celluloses to remove natural organic substances present in the water.

However, the use of activated charcoal requires a large amount of charcoal active and its cost is high.

Exchange resins are not very effective. It is indeed known in the field of ion exchange that natural organic substances are poisons for resins. The use of exchange resins also requires the management of an additional effluent related to regeneration, made necessary because of the high cost of these products.

The use of cationic celluloses in fibrous form is described in US Pat. No. 5,152,896. The crystalline nature of the cellulose in fibrous form means that only the accessible and modified surface is available for trapping, which limits the maximum adsorption capacity and slows the kinetics of exchange.

On the other hand all the above-mentioned products have the disadvantage of not effectively eliminating trihalomethanes precursors, carcinogenic, present in drinking water.

The need existed to find a way to eliminate natural organic substances present in liquids that do not have the disadvantages indicated above, that is to say which is simple to implement, inexpensive, and which is compatible with food applications.

One of the aims of the present invention is also to be able to effectively treat drinking water and in particular to eliminate precursors of trihalomethanes.

These and other objects are achieved by the present invention which therefore relates to the use of optionally modified and optionally insoluble starch for the removal of natural organic substances in liquids and in particular liquids for food such as the drinking water, drinks, fruit juices or syrups, and also natural waters, industrial waters, or sewage.

No particular limitation is imposed on the starch used in the invention, and examples of the starches which may be used include wheat starch, potato starch, corn starch, wheat starch, and starch. sweet potato starch, cassava starch, tapioca starch, sago starch, rice starch, glutinous corn starch, waxy maize starch, corn starch high amylose content, or mixtures thereof.

No particular limit is imposed on the purity of the starch. In this sense, starch-rich natural flours can also be used, such as wheat flour, potato starch, corn flour, rice powder, cassava flour, tapioca flour or their mixtures.

The term "starch" used hereinafter refers to purified starches as well as to natural flours.

The starch can be pretreated in order to lower the crystallinity level of the grains and make the chains accessible. It may be a process of pre-gelatinization such as for example a cooking with hot water or steam.

The starch is then optionally modified to improve its affinity for natural organic substances, and thus improve its ability to capture natural organic materials on the one hand and make it insoluble on the other hand which makes it easier to separate it from the liquid solution to be treated.

These modifications intended to improve the affinity of the starch for the natural organic substances, and to make it insoluble can be carried out separately and in the order that one wishes. It may also be possible to make these changes simultaneously.

Among the modifications of the starch intended to improve its affinity for natural organic substances include the introduction of cationic or cationizable groups. By cationizable group is meant groups which can be made cationic depending on the pH of the medium.

Among the cationic or cationizable groups there may be mentioned groups comprising quaternary ammoniums or tertiary amines, pyridiniums, guanidiniums, phosphoniums or sulfoniums.

The cationic modified starches used in the invention can be obtained by customarily reacting the aforementioned starch raw materials as such or after they have undergone the pre-gelatinization pretreatment mentioned above such as for example steaming with a suitable reagent.

The introduction of cationic or cationizable groups into the starch can be carried out by a nucleophilic substitution reaction.

In the case where it is desired to introduce an ammonium group, the adapted reagent used may be:

3-chloro-2-hydroxypropyltrimethylammonium chloride, sold under the name QUAB 188 by Degussa;

an epoxide carrying a quaternary ammonium such as 2,3-epoxypropyltrimethylammonium chloride sold under the name QUAB 151 by the company Degussa or analogous compounds;

diethylaminoethyl chloride; or Michael acceptors such as for example acrylates or methacrylates carrying quaternary ammonium or tertiary amines.

The introduction of cationic or cationizable groups into the starch can be carried out by esterification with amino acids such as, for example, glycine, lysine, arginine, 6-aminocaproic acid or with amino acid derivatives quaternized such as for example betaine hydrochloride.

The introduction of cationic or cationizable groups into the starch can also be carried out by a radical polymerization comprising the grafting of monomers comprising at least one cationic or cationizable group on the starch.

Radical priming can be carried out using cerium as described in the European Polymer Journal, vol. 12, p. 535-541, 1976. Radical priming can also be carried out by ionizing radiation and in particular electron beam bombardment.

The monomers comprising at least one cationic or cationizable group used to carry out this radical polymerization can be, for example, monomers comprising at least one ethylenic unsaturation and at least one quaternary or quaternizable nitrogen atom by adjusting the pH.

Among these monomers comprising at least one ethylenic unsaturation and at least one quaternary nitrogen atom or quaternizable by adjusting the pH can be mentioned the compounds of formulas (I), (II), (III), (IV) or (V) following:

^• the compound of general formula (I)

(I) in which:

- A ^nΘ represents a CI ion ^Θ, Br ^Θ, I ^Θ, ^2Θ SO _4, CO ₃ ²⁰ 'CH ₃ -OSO ₃ ⁹ - ^Θ 0H or CH ₃ -CH ₂ -OSO ₃ ^0, R ¹ to R ^{5, which are} identical or different, represent, independently of one another, an alkyl group having 1 to 20 carbon atoms, a benzyl radical or an H atom, and n is 1 or 2, or the compound of formula general (II)

(H) wherein:

X represents a group -NH or an oxygen atom O,

R ⁴ represents a hydrogen atom or an alkyl group having from 1 to 20 carbon atoms,

R ⁵ represents an alkene group having from 1 to 20 carbon atoms,

R ¹ , R ² and R ³ , which are identical or different, represent, independently of one another, an alkyl group having from 1 to 20 carbon atoms,

- B ^NΘ represents a CI ion ^Θ , Br ^Θ , I ^Θ , SO ₄ ^2Θ , CO ₃ ^2Θ 'CH ₃ -OSO ₃ ⁸ , 0H ^Θ or CH ₃ -CH ₂ -OSO ₃ ⁰ , and

n is 1 or 2, or the compound of general formula (III)

(III) in which :.

R ¹ to R ⁶ , which may be identical or different, represent, independently of one another, a hydrogen atom or an alkyl group having from 1 to 20 carbon atoms, but with one of the groups R ¹ to R ⁶ representing a group -CH = CH _2,

- C ^NΘ represents a CI ion ^Θ, Br ^Θ, ^Θ I, SO ₄ ²⁰ CO _³²⁰¹ ⁰ CH ₃ -OSO _3, OH or CH ₃ ⁰ -CH ₂ - ⁰ OSO _3, and

n is 1 or 2, or the compound of general formula (IV)

(IV) wherein:

- D ^"0 represents a CI ion ^®, Br ^0, I ^0, SO ₄ ²⁰ CO ₃ ²⁰ 'CH ₃ -OSO ₃ ^0, ⁰ OH or CH ₃ -CH ₂ - ⁰¹ and OSO ₃

n is 1 or 2.

Preferably, the monomers comprising at least one ethylenic unsaturation and at least one quaternary or quaternizable nitrogen atom are chosen from:

2-dimethylaminoethyl acrylate (ADAM),

quaternized 2-dimethylaminoethyl acrylate (ADAM-Quat),

2-dimethylaminoethyl methacrylate (MADAM),

quaternized 2-dimethylaminoethyl methacrylate (MADAM-Quat),

the quaternized 2-diethylaminoethyl methacrylate form chloride called pleximon 735 or TMAE MC 80 by the company Rohm,

- diallyldimethylammonium chloride (DADMAC),

trimethylammonium propylmethacrylamide form chloride called MAPTAC or

- their mixtures.

The cationic modified starch may contain cationic or cationizable units resulting from a chemical transformation after polymerization of precursor monomers of cationic or cationizable functions. By way of example, mention may be made of polypchloromethylstyrene which, after reaction with a tertiary amine such as trimethylamine forms quaternized polyparatrimethylaminomethylstyrene.

Cationic or cationizable units are associated with negatively charged counterions. These counterions can be chosen from chloride ions, bromides, iodides, fluorides, sulphates, methyl sulphates, phosphates, hydrogen phosphates, phosphonates, carbonates, hydrogencarbonates or hydroxides.

Preferably, counter-ions selected from hydrogenophosphates, methylsulfates, hydroxides and chlorides are used.

The degree of substitution of the cationic modified starches used in the invention is at least 0.01 and preferably at least 0.1.

If the degree of substitution is less than 0.01, the effectiveness of carrying out the removal of natural organic matter from the liquid to be treated is reduced.

If the degree of substitution exceeds 0.1, the starch inevitably swells in the liquid. In order to be able to use a modified modified starch at a rate higher than 0.1, it is preferable to modify it to make it insoluble. These changes are described later.

The degree of substitution of the cationic modified starch corresponds to the average number of cationic charges per sugar unit.

Among the modifications of the starch intended to improve its affinity for natural organic substances, mention may also be made of the introduction of groups carrying an anionic or anionizable filler.

The anionic modified starch used in the invention can be obtained by customarily reacting the starches mentioned above with an anionizing agent such as propane saltone, butane saltone, monochloroacetic acid, chlorosulfonic acid, maleic anhydride, succinic acid anhydride, citric acid, sulfates, sulfonates, phosphates, phosphonates, orthophosphates, polyphosphates, metaphosphates and the like.

The degree of substitution of the anionic modified starches used in the invention is at least 0.01 and preferably at least 0.1.

If the degree of substitution exceeds 0.1, as in the case of cationic modified starches, the starch inevitably swells in the liquid, and in the same way that in the case of cationic modified starches, in order to be able to use a modified modified starch at a rate higher than 0.1, it is preferable to modify it to make it insoluble. These changes are described later.

The degree of substitution of the anionic modified starch corresponds to the average number of anionic charges per sugar unit.

Among the modifications of the starch intended to improve its affinity for natural organic substances, mention may also be made of the introduction of hydrophilic or hydrophobic uncharged groups.

Among the hydrophilic groups that can be introduced include in particular one or more saccharide or oligosaccharide residues, one or more ethoxy groups, one or more hydroxyethyl groups, or one or more oligoéhylène oxide.

Among the hydrophobic groups which can be introduced include an alkyl group, aryl, phenyl, benzyl, acetyl, hydroxybutyl, hydroxypropyl or their mixture.

By alkyl or aryl or acetyl radical is meant alkyl or aryl or acetyl radicals having from 1 to 22 carbon atoms.

The degree of substitution of the modified starches by hydrophilic or hydrophobic uncharged groups used in the invention is at least 0.01 and preferably at least 0.1.

The degree of substitution of the modified starch by hydrophilic or hydrophobic uncharged groups corresponds to the average number of hydrophilic or hydrophobic uncharged groups per sugar unit.

It is possible to carry out several of the modifications proposed above for increasing the affinity of starch for natural organic substances on the same starch.

Among the modifications of the starch intended to make it insoluble, mention may in particular be made of the possibility of carrying out a chemical crosslinking of the starch, or of adsorbing it chemically or physically on a mineral or organic support that is insoluble in water or by exploiting its natural crystallinity. In the case where the natural crystallinity of the starch does not allow the final product to have a mass fraction of soluble organic less than 10% then the starch is also chemically crosslinked so as to satisfy this criterion.

Preferably, a chemical crosslinking of the starch is used to make it insoluble.

The chemical crosslinking of the starch can be obtained by the action of a crosslinking agent chosen from formaldehyde, glyoxal, halohydrins such as epichlorohydrin or epibromhydine, phosphorus oxychloride, polyphosphates, diisocyanates, bi-ethylene urea, polyacids such as adipic acid, citric acid, acrolein and the like.

The chemical crosslinking of the starch can also be obtained by the action of a metal complexing agent such as, for example, zirconium (IV).

The chemical crosslinking of the starch can also be obtained under the effect of ionizing radiation.

The level of insolubilization of the starch is satisfactory when the mass fraction of organic soluble in starch is less than 10%.

As indicated above, the modifications intended to improve the affinity of the starch for the natural organic substances, and the modifications intended to make it insoluble, can be carried out separately and in the order that one wishes. It may also be possible to make these changes simultaneously.

By way of example, where the modifications of the starch are carried out simultaneously, there may be mentioned an insoluble cationic starch obtained by placing starch with excess epichlorohydrin and a trimethylamine in the presence of starch. Epichlorohydrin generates in situ a reagent carrying a quaternary ammonium which will allow to make the cationic starch on the one hand. In addition, the excess epichlorohydrin makes it possible to crosslink the starch.

The optionally modified and optionally insoluble starch of the invention may be used in the form of a powder or may be shaped in the form of granules.

The crosslinking chemical reaction can be used to obtain insoluble granules.

The optionally cationic starches may be shaped by granulation during the crosslinking reaction in order to obtain insoluble particles of the order of one millimeter (for example between 200 μm and 5 mm), which makes it possible to easily separate them from the water to be treated.

In an industrial installation, these granulated products have the advantage of being used in column, in the same way as the exchange resins, thus offering a large exchange surface and an increased retention capacity.

A method of preparation of the granular crosslinked cationic starches is given in the examples below. It is possible to use the optionally modified and optionally insoluble starch of the invention alone, or else mixed with other scavengers natural organic substances such as, for example, exchange resins, activated charcoal or cationic celluloses.

Among the possible combinations, the combination of an optionally modified and optionally insoluble starch of the invention with activated charcoal is preferred.

The mass fraction of starch in the mixture may be between 5-95% and reciprocally the mass fraction of active carbon may be between 95-5%.

Preferably, the mass fraction of starch in the mixture may be between 40-60% and conversely the mass fraction of active carbon may be between 60-40%.

It is also possible to mix the optionally modified and optionally insoluble starch of the invention with inert fillers such as polymer powder or sand to ballast it.

The elimination of natural organic substances present in the liquid is carried out by introducing the optionally modified and optionally insoluble starch of the invention into the liquid to be treated, stirring for the necessary time which is between a few minutes and a few hours, then removing from the treated liquid the starch on which the natural organic substances have been adsorbed, by means of an operation such as separation by centrifugation, filtration including membrane, sedimentation or the like.

In addition, it is possible, for example, to use sequentially activated carbon treatment.

In particular, as indicated in the examples presented below, the combination of a treatment with starch and a treatment with activated carbon makes it possible in particular to eliminate in a complementary way natural organic substances.

The optionally modified and optionally insoluble starch of the invention has the advantage of effectively eliminating trihalomethane precursors.

Natural organic matter in water is mainly the result of the total or partial decomposition of plants, animals and microorganisms. They occur naturally in natural waters but their quantities and characteristics are different depending on the water sources considered (lakes, rivers, groundwater, stream, ocean), their geographical location and the season. However, it is possible to give average values of concentrations of natural organic matter encountered in water intended for the production of drinking water: for surface water, the concentration varies from 2 to 10 mg / l for total organic carbon ( COT); while for groundwater, the average value of total organic carbon (TOC) is between 0.5 and 1.0 mg / l.

The nature of natural organic matter varies from one watercourse to another. This finding implies that the chemical characterization of natural organic matter can hardly be generalized.

In general, it is considered that natural organic matter is divided into two distinct categories: the hydrophobic material (humic and fulvic acids) and the hydrophilic material (proteins, carbohydrates, amino acids, peptides).

Humic acids are the compounds which in natural organic matter have the highest molecular weight. This is mainly due to the high concentration of aromatic carbon relative to the concentration of carboxylic acids and carbonyls.

Fulvic acids are of lower molecular weight than humic acids. Their aromatic carbon concentration is lower than that of humic acids. However, the carbonyl and carboxylic acid concentrations of fulvic acids are higher than those of humic acids. Fulvic acids represent the majority fraction of natural organic matter (nearly 50%) compared to the fraction of humic acids which is of the order of 5%.

Natural organic matter in water may also include algal toxins. These are organic molecules synthesized by bacteria. These algal toxins include dermatotoxins, neurotoxins and hepatotoxins. Among the hepatotoxins mention may be made of microcystins and in particular microcystin-LR. These algal toxins can cause organoleptic problems but especially they can lead to health problems. This is particularly the case of hepatotoxins and in particular microcystin-LR.

Natural organic materials present in beverages, fruit juices and syrups are well known to those skilled in the art.

Sugar dyes which are macromolecules in the form of hydrophobic carbon chains and have a hydrophilic end at their weak acidic function can be mentioned for example in the case of sugar-sweetened drinks.

Organic matter present in industrial effluents depends on industrial processes in which water has been used.

Among the organic materials present in the industrial effluents mention may be made of so-called manufacturing dyes or natural dyes. Reference can be made to the document entitled "coupling of decolorization and nanofiltration of regeneration eluates in cane refining" AVH association, 6th Symposium, Reims, March 1999.

The cationic modified starch or the cationic modified starch made insoluble is used in the case where the liquid to be treated contains natural organic substances which have anionic or anionizable substituent groups, for example phenols, phenates, carboxylic acids, carboxylates, phosphates or sulphates. , hydrogen sulfides.

The anionic modified starch or the anionic modified starch made insoluble is used in the case where the liquid to be treated contains natural organic substances which have cationic or cationizable groups, for example amines, or ammonium groups.

The starch modified with hydrophilic non-charged groups or the starch modified with hydrophilic and insoluble non-charged groups is used in the case where the liquid to be treated contains natural organic substances which have hydrophilic groups, for example saccharide residues or oligosaccharides. the starch modified with hydrophobic uncharged groups or the starch modified with hydrophobic uncharged groups and rendered insoluble is used in the case where the liquid to be treated contains natural organic substances which have hydrophobic groups, for example alkyl, phenyl, benzyl, acetyl, hydroxybutyl, or hydroxypropyl.

In addition, two or more of the above-mentioned types of starch and / or modified starch may be used as a mixture of two or more types or may be used together.

The amount of modified starch added can be suitably selected depending on the concentration of natural organic substances in the liquid to be treated and the exchange capacity of the modified starch.

The modified starch of the invention is also useful for removing organic substances contained in the urine. The following examples are given for illustrative but not limiting.

Examples

A- Examples for preparing the starches of the invention 1) powdered starch

Example A-1 (Starch A): synthesis of an insolubilized cationic starch.

In a reactor of 1 liter cylindrical double-wrapped, equipped with an anchor-type mechanical stirring, a dropping funnel and a condenser, 250 ml of demineralized water and 1.2538 g of sodium hydroxide are introduced. . The assembly is placed under a nitrogen atmosphere and with stirring at 100 revolutions / minute. Once the solubilized sodium hydroxide, 50.053 g of cold soluble starch powder are introduced into the reactor. The assembly is heated to 60 ^° C. (double-jacket temperature) by circulation of hot water. Once the temperature is reached, the mixture is kept stirring for one hour. 99 ml of Quab 151 (solution of epoxypropyltrimethylammonium chloride 70% in water sold by Degussa AG) are then added dropwise over 20 minutes. Once the addition is complete, the reactor is maintained at a temperature of 60 ^° C. with stirring for 6 hours. After cooling to room temperature, the pH of the reaction medium is brought to 7 by addition of a 0.1N hydrochloric acid solution. The reaction medium is then poured into 4 liters of absolute ethanol stirred using a homogenizer. Ultra-Turrax type. The precipitated polymer is retained by filtration on frit No. 3, redispersed in 2 liters of ethanol, refiltered and dried for 16 hours at 50 ^° C. in a vacuum oven compensated at 20 mbar with nitrogen U.

After drying, 57.38 g of a white powder, soluble in water, which precipitates in the presence of anionic surfactant sodium dodecyl sulfate (SDS). This particular behavior reveals that the introduction of cationic charges on the polymer has been well done.

Elemental analysis shows that the cationized starch contains 4% nitrogen, which corresponds to a degree of cationic substitution of 0.8.

For insolubilization by chemical crosslinking, 16.67 g of cationic starch powder obtained in the preceding step are introduced into a reactor containing 135 ml of isopropyl alcohol (2-propanol). Stirring is carried out for 3 minutes at 100 revolutions / minute while maintaining the reaction medium under a nitrogen atmosphere. 6 ml of 50% sodium hydroxide solution are then added, followed by 3.9 ml of epibromohydrin after 3 minutes. The mixture is brought to 60 ^° C. for 1 hour, then cooled. After returning to ambient temperature, 310 ml of deionized water are added to the reactor, the mixture is stirred for 2 hours, then the stirring is stopped and the mixture is left standing for 2 hours to decant the solid. The supernatant is removed by suction using a cane with a filter tip, and then 300 ml of demineralized water are reintroduced into the reactor. The reaction medium is brought to pH = 6 by addition of 1N hydrochloric acid. It is then placed under stirring for 2 hours. The solid + liquid mixture is then filtered on No. 3 frit. The cake is taken up in one liter of demineralized water heated at 70 ^° C. with vigorous stirring for 2 hours at which point the stirring is stopped and allowed to settle. The supernatant is removed by suction using a filter nozzle cane. The washing operation by redispersion in 1 liter of demineralized water, decantation and removal of the supernatant is repeated 4 times with cold water.

At the end of the last washing, the decanting solid is separated and then frozen and dried by lyophilization. 15 g of white powder is obtained very aerated, which is easily absorbed with water but does not solubilize.

Example A-2 (Starch B): synthesis of an insolubilized cationic starch.

In a reactor of 1 liter cylindrical double-wrapped, equipped with an anchor-type mechanical agitation, a dropping funnel and a condenser, 75 ml of demineralised water are introduced, then 750 mg of sodium chloride and 50 g of waxy maize starch. The whole is placed under a nitrogen atmosphere and with stirring at 100 rpm. 5.2 ml of epibromohydrin are added, the mixture is stirred for 3 minutes and then 3 g of pelletized sodium hydroxide dissolved in 20 ml of demineralized water are added. The reaction medium has a pasty, very viscous appearance. Stirring is then stopped and allowed to react at room temperature (25 ° C.) for 16 hours. At the end of this time, the reaction mass became friable. A solution of 23 g of pelletized sodium hydroxide in 60 ml of demineralized water is added and the stirring is started again at 100 revolutions / minute. The dough breaks up and disperses in the liquid. After 30 minutes, the reaction medium is heated to 65 ° C. Once at this temperature, 90 ml of Quab 188 (69% chlorohydroxypropyltrimethylammonium chloride in water sold by Degussa AG) is added dropwise over 30 minutes. The addition is complete, the reactor is maintained at a temperature of 60 ^° C. with stirring for 2 hours. Stirring is then stopped and allowed to cool to room temperature. It is kept at rest for 2 hours to decant the solid. The supernatant is removed by suction using a cane with filter tip, then reintroduced 600 ml of demineralized water into the reactor. The reaction medium is brought to pH = 6 by addition of 1N hydrochloric acid. It is then stirred for 2 hours. The solid + liquid mixture is then filtered on No. 3 frit. The cake is included in

1 liter of demineralized water heated to 70 ⁰ C with vigorous stirring for 2 hours after which stirring is stopped and allowed to settle. The supernatant is removed by suction using a filter nozzle cane. The washing operation by redispersion in 1 liter of demineralized water, decantation and removal of the supernatant is repeated 4 times with cold water. At the end of the last washing, the decanting solid is separated and then frozen and dried by lyophilization.

60 g of very airy white powder is obtained, which is easily impregnated with water but does not dissolve.

Elemental analysis on nitrogen shows that this product has a cationic DS of 0.12.

Example A-3 (Starch C): Synthesis of an insolubilized cationic starch.

The procedure is identical to that of Example A-2, except that the raw material is normal corn starch and the final product is dried in a vacuum oven at 50 ^° C. 55, 27 g of white powder, which is easily absorbed by water but does not dissolve. Elemental analysis on nitrogen shows that this product has a cationic DS of 0.15.

2) granular starches

Method of preparation of crosslinked granular cationic starches:

Example A-4 (G1 Starch):

In a beaker of 250 ml of tall form, 20 g of cationic starch Hi-Cat 1574A marketed by Roquette Frères is introduced. 5 g of deionized water are then added at ambient temperature to the powder, and the mixture is then homogenized manually using a plastic spatula. Under the action of moisture and agitation, granules are formed. 2 g of 98% epibromohydrin (Sigma Aldrich) are then added, still at room temperature, and the mixture is further homogenized using the spatula. Finally, 7.5 g of a 30% by weight aqueous solution of NaOH is added, still at room temperature. The mixture is again homogenized using the plastic spatula. The beaker is covered with a stretch film (Parafilm) and placed in a bath thermostated at 60 ° C. Regularly, the stretch film is removed to be able to stir the contents of the beaker with a spatula. The beaker is taken out of the thermostated bath after 1 hour. After this reaction step, the granules obtained are washed. 10 g of product are placed in a 400 ml beaker containing 100 ml of demineralized water. The mixture is stirred for 5 minutes with the aid of a magnetic stirrer, and the solid is then recovered. filtration (paper filter on Buchner). The washing is repeated twice, in order to wash the product in total 3 times. The washed solid is then dried in an oven under vacuum (approximately 30 mm Hg, 40 ^° C.) for 24 hours. 5.6 g of solid are obtained, ie a recovery yield of 97%, relative to the 6.03 g of insoluble solids initially contained in the 10 g of product subjected to washing. The Starch G1 sample contains 1.18% nitrogen (on the dry extract, determined by the Kjeldhal method), which corresponds to a degree of cationic substitution of approximately 0.14.

Example A-5 (G2 Starch):

In a 5-liter coulter mixer (Lodige GmbH), 500 g of Hi-Cat 1574A cationic starch sold by Roquette Frères are charged at room temperature. The mixer is started (speed indicator set to 4) to fluidize the bed of powder. 25 g of water are sprayed in 1 minute on the powder, then 100 g of a 32% by weight aqueous solution of NaOH in 2 minutes. Finally, 50 g of epibromohydrin 98% (Sigma Aldrich) are sprayed at room temperature in 2 minutes. 15 minutes after switching on of the mixer, the speed indicator is set to 3, and the water of a thermostated bath at 63 ° C. is circulated in the double jacket of the mixer. 18 minutes after starting the mixer, water (total 235 g) is added regularly by spraying in order to improve the granulation. 1 hour 25 minutes after starting the mixer, water is circulated at room temperature in the double jacket of the mixer to cool the product. 1 hour 28 minutes after switching on the mixer, the product is at 42 ° C, and stirring is stopped to discharge it. After this reaction step, the product obtained is washed. 91 g of product (corresponding to 50 g of Hi-Cat 1574A cationic starch) are placed in a 1-liter beaker containing 500 ml of demineralized water. The mixture is stirred for 5 minutes with the aid of a magnetic stirrer, and the solid is then recovered by filtration (paper filter on Buchner). The washing is repeated twice, in order to wash the product in total 3 times. The washed solid is then dried in an oven under vacuum (approximately 30 mm Hg, 40 ^° C.) for 24 hours. The product obtained is visually insoluble in water. The starch G2 sample contains 1.18% nitrogen (on the dry extract, determined by the Kjeldhal method), which corresponds to a degree of cationic substitution of approximately 0.14. Example A-6 (G3 starch):

In a kitchen blender (Braun model 4142), 100 g of native corn starch (Roquette Frères) are loaded. The stirring speed is adjusted by means of a voltage variator on which the mixer is connected, in order to set the powder in motion while avoiding the flight. 25 g of deionized water are then slowly added at ambient temperature, followed by 35.5 g of a 32% by weight aqueous solution of NaOH on the stirred powder. After a few seconds of mixing, a cohesive granulated powder is obtained. 50 g of this mixture (ie 31.1 g of native starch) are placed in a beaker of 250 ml of high form, and 3.1 g of 98% epibromohydrin (Sigma Aldrich) are added, and the mixture is homogenized. using a plastic spatula. The beaker is covered with a stretchable film (Parafilm) and placed in a thermostatically controlled bath at 60 ^° C. The stretchable film is regularly removed in order to be able to stir the contents of the beaker with the aid of a spatula. After 1 hour, 92.4 g of 65% CFZ Reagens S (65% by weight aqueous solution of 3-chloro-2-hydroxypropyltrimethylammonium chloride, Sachem Europe BV) are added. The beaker covered with stretch film is left for 2 hours 40 minutes in the bath thermostated at 60 ^° C, then overnight at room temperature.

After these reaction steps, the granules obtained are washed. The contents of the beaker are transferred to a 600 ml beaker, to which 300 ml of demineralized water are added. The mixture is stirred for 5 minutes with the aid of a magnetic stirrer, and the solid is then recovered by filtration (paper filter on Buchner). The washing is repeated twice, in order to wash the product in total 3 times. After the ^3rd wash, the filtration is greatly slowed by the presence of fine particles (starch grains uncrosslinked). The product is then washed on a 400 μm sieve with about 300 ml of demineralized water. A total of 3 washes are carried out on this sieve, before filtering the product one last time on Buchner to eliminate as much water as possible. The product is then dried in a vacuum oven (about 30 mm Hg, 40 ° C) for 15 hours. 29.5 g of solid containing 8.3% relative humidity are obtained. The starch G3 sample contains 0.23% nitrogen (on the dry extract, determined by the Kjeldhal method), which corresponds to a degree of cationic substitution of approximately 0.015.

Effectiveness of insolubilization

The insolubilization rate of these 3 samples is satisfactory since when they are dispersed in ultrapure water at the height of 100 mg / l, the carbon content in the supernatant separated by centrifugation (at 5000 rpm during 15 minutes) is from in the order of 0.15 mg / l, ie 0.15% of soluble organic compounds. This content of soluble organic compounds is well below the recommended 10%.

B-Evaluation Examples of the Starches of the Invention

In all of the examples, the determination of the natural organic materials is carried out either by spectrophotometry u.v. at 254 nm with a Shimadzu UV-160 model 204- 04550, or by assaying total organic carbon using the Shimadzu TOC-5000A analyzer. These measurements are performed after filtering the samples using PVDF Millex syringe filters and 0.45 μm porosity, previously rinsed with ultrapure water.

Example B-1:

This test is carried out on natural water from the region of Rennes which has previously undergone a coagulation / flocculation treatment. In a 150 ml pyrex beaker, 1 mg of crosslinked cationic starch of Example A-1 (starch A) is introduced with stirring into 100 ml of water to be treated. This experiment is done at TC. For determined contact times, the residual concentration of natural organic matter in solution is measured. The results are shown in Table I.

Table I

Percentage of abatement

Contact Time (min) Absorbance u.v. at 254 nm the absorbance u.v. at 254nm

2 0.172 3.4

10 0.159 10.7

20 0.154 13.5

30 0.155 12.9

60 0.151 15.2

190 0.148 16.9

430 0.149 16.3

1330 0.147 17.4

Natural water after 0178 coagulation / flocculation

This test demonstrates the effectiveness of the cross-linked cationic starch of Example A-1 in removing natural organic matter. Furthermore, it is shown that the kinetics of adsorption is fast since after 30 minutes of contact time, one reaches about 75% of the performances obtained at equilibrium.

Example B-2:

This test is carried out on natural water from the region of Rennes which has previously undergone a coagulation / flocculation treatment. In 150 ml pyrex beakers, specific amounts of cationic starch are introduced with stirring and at a temperature of 7 ° C. crosslinked from Example A-1 (starch A) to 100 ml of the water to be treated. After a contact time of 30 minutes, the residual concentration of natural organic matter in solution is measured. The results are shown in Table II.

Table II

Percent concentration

Organic Carbon Percentage UV Absorbance at

Cationic starch of elimination of

Total (C.O.T) in mg / l of 254 nm C.O.T removal

Reticulated in ppm UV absorbance

1.97 ± 0.10 18 0.155 ± 0.002 19 25 1, 85 ± 0.10 23 0.134 ± 0.002 30 50 1.72 ± 0.10 28 0.124 ± 0.002 35 100 1, 59 ± 0.10 34 0.110 ± 0.002 43 200 1.29 ± 0.10 46 0.088 ± 0.002 54

Natural water after

2.40 ± 0.10 0.192 ± 0.002 coagulation / flocculation

This example demonstrates the influence of the starch dose on the elimination of natural organic matter: the higher the starch dose, the higher the percentage of removal of natural organic matter. However, it appears that performance is capping at high doses. This is probably related to the fact that the cross-linked cationic starch does not interact with all the natural organic materials but only with a fraction of them, this fraction being of the order of 50%.

Example B-3:

Comparative tests were carried out between Picactive active carbon powder PCO 15-35 marketed by PICA, crosslinked cationic starch of Example A-1

(Starch A) and a cross-linked cationic powder-cationic active carbon mixture in the mass proportion 50% -50%.

These tests were performed on natural water from the region of Rennes which has previously undergone a coagulation / flocculation treatment. In addition, each test has been reproduced at least 5 times.

For each test, 1 mg of the test product is dispersed with stirring and at a temperature of 7 ° C. in 100 ml of water to be treated and after a contact time of 30 minutes, the residual organic matter concentration is determined. in solution. The results are shown in Table III. Table III

Organic Carbon Percentage

Percentage UV absorbance at

Total (C.O.T) elimination elimination of C.O.T 254 nm mg / l UV absorbance

Rennes natural water

2.40 ± 0.10 after coagulation / flocculation 0.192 ± 0.002

Active Carbon in Picactive Powder

2.10 ± 0.10 13% 0.173 ± 0.002 10% PCO 15-35

Cationic Starch Reticulated 2.00 ± 0.10 17% Starch A 0.150 ± 0.002 22%

Activated Carbon Powder 50% Starch A 50% 1, 95 ± 0.10 19% 0.146 ± 0.002 24%

These tests demonstrate that the crosslinked cationic starch of Example A-1 (starch A) is more effective than powdered activated carbon for eliminating the precursors of trihalomethanes since it allows a greater reduction of the absorbance of the water. In addition, its effectiveness vis-à-vis the overall nature of natural organic materials is similar to that of activated carbon powder.

Finally, through this example, also shows the interest of combining the use of crosslinked cationic starch with that of activated carbon to improve the performance of the latter.

Example B-4:

Comparative tests were carried out between crosslinked cationic starches with structural parameters and variable production methods.

These tests were performed on natural water from the region of Rennes which has previously undergone a coagulation / flocculation treatment. For each test, 1 mg of the test product is dispersed with stirring and at a temperature of 7 ° C. in 100 ml of water to be treated and after a contact time of 30 minutes, the residual organic matter concentration is determined. natural. The results are shown in Table IV.

Table IV

Organic Carbon Percentage

Percentage UV absorbance at

Total (C.O.T) elimination elimination of C.O.T 254 nm mg / l UV absorbance

Rennes natural water

2.48 ± 0.10 after coagulation / flocculation 0.193 ± 0.002

Starch A 2.17 ± 0.10 13% 0.158 ± 0.002 18%

Starch B 2.20 ± 0.10 11% 0.178 ± 0.002 8%

Starch C 2.24 ± 0.10 10% 0.182 ± 0.002 6% It is shown in this example that crosslinked cationic starches, which have different structural parameters and which were obtained according to different synthetic routes, lead to equivalent performance in terms of TOC for a use dose of 10 ppm and a time. contact time of half an hour.

On the other hand, it is necessary to note the singularity of the crosslinked cationic starch of Example A-1 (starch A) for the elimination of precursors of trihalomethanes. This specificity is probably related to the greater accessibility of the adsorption sites that would result from the steaming pretreatment that the starch has undergone before being modified.

Example 5

Comparative tests were carried out between crosslinked cationic starches with structural parameters, a variable method of obtaining and shaping.

These tests were performed on natural water from the region of Rennes which has previously undergone a coagulation / flocculation treatment. For each test, 1 mg of the test product is dispersed with stirring and at a temperature of 7 ° C. in 100 ml of water to be treated, and after a contact time of 15 hours, the residual concentration of organic matter is determined. in solution. The results are shown in Table V.

Table V

Percentage

UV absorbance at 254 nm removal UV absorbance

Natural Rennes water after coagulation / flocculation 0,170 ± 0,002

Starch A 0.140 ± 0.002 17.5% Starch C 0.153 ± 0.002 10% Starch G1 0.159 ± 0.002 6% Starch G2 0.156 ± 0.002 8% Starch G3 0.171 ± 0.002 0%

In this example, the specificity of the crosslinked cationic starch of Example A-1 (starch A) is found for the removal of precursors of trihalomethanes. Moreover, it is shown that granular cationic starches are effective in removing natural organic matter at a dose of 10 ppm since their degree of cationic substitution is sufficiently high (> 0.015).

Claims

1. Use of cationic rendering starch, by the introduction of one or more cationic or cationizable groups, and insoluble for the removal of natural organic substances contained in liquids.

2. Use according to claim 1, characterized in that the starch is selected from wheat starch, potato starch, corn starch, sweet potato starch, tapioca starch , cassava starch, sago starch, rice starch, glutinous corn starch, waxy maize starch, high amylose corn starch or mixtures thereof.

3. Use according to any one of claims 1 to 2, characterized in that the starch undergoes pretreatment pre-gelatinization such as cooking with hot water or steam.

4. Use according to one of claims 1 to 3, characterized in that the cationic or cationizable groups are selected from groups comprising quaternary ammonium or tertiary amines, pyridiniums, guanidiniums, phosphoniums or sulfoniums.

5. Use according to any one of the preceding claims, characterized in that the introduction of cationic or cationizable groups in the starch is carried out by a nucleophilic substitution reaction.

6. Use according to any one of claims 1 to 5, characterized in that the introduction of cationic or cationizable groups in the starch is carried out by an esterification with amino acids such as for example glycine, lysine, lysine. arginine, 6-aminocaproic acid, or with quaternized amino acid derivatives such as, for example, betaine hydrochloride.

7. Use according to any one of claims 1 to 5, characterized in that the introduction of cationic or cationizable groups in the starch is carried out by a radical polymerization comprising the grafting of monomers comprising at least one cationic or cationizable group on the starch.

8. Use according to claim 7, characterized in that the monomers comprising at least one cationic or cationizable group used to carry out this free radical polymerization chosen from the compounds of formulas (I), (II), (III), ( IV) or (V):

^• the compound of general formula (I)

(I) in which:

- A ^nΘ represents a CI ion ^Θ , Br ^Θ , I ^Θ , SO ₄ ^2Θ , CO ₃ ²⁰ 'CH ₃ -OSO ₃ ⁰ OH ^Θ or CH ₃ -CH ₂ -OSO ₃ ⁰ ,

R ¹ to R ^{5, which are} identical or different, represent, independently of one another, an alkyl group having from 1 to 20 carbon atoms, a benzyl radical or an H atom, and

n is 1 or 2, or the compound of general formula (II)

(H) in which: X represents a group -NH or an oxygen atom O, R ⁴ represents a hydrogen atom or an alkyl group having from 1 to 20 carbon atoms,

R ⁵ represents an alkene group having from 1 to 20 carbon atoms,

R ¹ , R ² and R ^{3, which are} identical or different, represent, independently of one another, an alkyl group having from 1 to 20 carbon atoms,

- B represents a CI ion ^NΘ ^®, Br ^e, I ^e, SO ₄ ^2Θ, CO _³²⁰¹ CH ₃ -OSO ₃ ^0, ^Θ OH or CH ₃ -CH ₂ -OSO ₃ ^0, and

n is 1 or 2, or the compound of general formula (III)

(III) wherein:

R ¹ to R ^{6, which are} identical or different, represent, independently of one another, a hydrogen atom or an alkyl group having from 1 to 20 carbon atoms, but with one of the groups R ¹ to R ⁶ representing a group -CH = CH _2,

- C represents an ion ^NΘ ⁰ Cl, Br ^0, I ^0, SO ₄ ²⁰ CO ₃ ²⁰ 'CH ₃ -OSO ₃ ^0, ⁰ OH or CH ₃ -CH ₂ - OSO ₃ ^0, and

n is 1 or 2, or the compound of general formula (IV)

CH ₂

CH CH _KΘ CH ₂ D n 0

CH-CH ₂ ^S CH ₃

CH ₂ ^

(IV) in which :

- D represents a ^nΘ ^® ion CI, Br ^Θ, ^Θ I, SO ₄ ²⁰ CO ₃ ²⁰ 'CH ₃ -OSO ₃ ^0, ^Θ OH or CH ₃ -CH ₂ -

OSO ₃ ⁰ 'and

n is 1 or 2.

9. Use according to any one of claims 7 to 8, characterized in that the monomers comprising at least one cationic or cationizable group used to carry out this radical polymerization are chosen from:

2-dimethylaminoethyl acrylate (ADAM),

quaternized 2-dimethylaminoethyl acrylate (ADAM-Quat),

2-dimethylaminoethyl methacrylate (MADAM),

quaternized 2-dimethylaminoethyl methacrylate (MADAM-Quat)

- diallyldimethylammonium chloride (DADMAC),

trimethylammonium propylmethacrylamide form chloride called MAPTAC or

- their mixtures.

10. Use according to any one of the preceding claims, characterized in that the cationic or cationizable groups are associated with negatively charged counter-ions selected from chloride ions, bromides, iodides, fluorides, sulfates, methylsulfates, phosphates, hydrogen phosphates, phosphonates, carbonates, hydrogencarbonates, or hydroxides.

11. Use according to any one of the preceding claims, characterized in that the degree of substitution of the modified starches by introducing one or more cationic groups is at least 0.01 and preferably at least 0.1. .

12. Use according to any one of the preceding claims, characterized in that the insoluble starch is obtained by a chemical crosslinking of the starch, or by the adsorbent chemically or physically on a mineral or organic support insoluble in the water, and / or by exploiting its natural crystallinity.

13. Use according to the preceding claim, characterized in that the insoluble starch is obtained by chemical crosslinking.

14. Use according to claim 13, characterized in that the chemical crosslinking of the starch is obtained by the action of a crosslinking agent selected from formaldehyde, glyoxal, halohydrins such as epichlorohydrin or epibromohydrin , phosphorus oxychloride, polyphosphates, diisocyanates, bisethylene urea, polyacids such as adipic acid, citric acid, acrolein and the like.

15. Use according to claim 13, characterized in that the chemical crosslinking of the starch is obtained by the action of a metal complexing agent such as for example zirconium (IV).

16. Use according to claim 13, characterized in that the chemical crosslinking of the starch is obtained under the effect of ionizing radiation.

17. Use according to any one of claims 12 to 16, characterized in that the crosslinking is conducted until the mass fraction of organic soluble in starch is less than 10%.

18. Use according to any one of claims 1 to 17, characterized in that the modified and insoluble starch of the invention is used in the form of a powder or shaped in the form of granules.

19. Use according to any one of claims 1 to 18, characterized in that the modified and insoluble starch of the invention is mixed with other scavengers natural organic substances such as for example activated carbon or cationic celluloses .

20. Use according to any one of claims 1 to 18, characterized in that the modified and insoluble starch of the invention is mixed with inert fillers such as sand or polymer powder.

21. Use according to any one of claims 1 to 20, characterized in that the natural organic materials comprise algal toxins, and / or the hydrophobic material (humic and fulvic acids) and / or the hydrophilic material (proteins, carbohydrates, amino acids, peptides).

22. Use according to any one of claims 1 to 20, characterized in that the cationic modified starch or cationic modified starch and made insoluble is used in case the liquid to be treated contains natural organic substances which have groups anionic or anionizable substituents, for example carboxylates, phenates, phosphates, sulphates or mixtures thereof.

23. Use according to any one of claims 1 to 22, characterized in that the starch is a mixture of two or more of the types mentioned above of starch and / or modified starch.

24. Use according to any preceding claim for removing natural organic substances from drinking water.

25. Use according to any preceding claim for removing natural organic substances from natural or waste water.

26. Use according to any preceding claim for removing natural organic substances from beverages such as fruit juices or syrups.

27. Use according to any one of the preceding claims for removing organic substances contained in the urine.