LT6229B - Modified starch flocculant and method of producing thereof - Google Patents

Abstract

The invention is designed for the efficient cross-linked cationic starch flocculant of the broad flocculation window, which during the flocculation of suspensions is able to bind soluble anionic pollutants, and for method of production of such flocculant. Cross-linked cationic starch is obtainable by cross-linking and cationization of starch in one-stage or two-stage process. The flocculant is obtained by dispergation of microgranules of cross-linked cationic starch with use of shear forces in water or aqueous mixture with multifunctional alcohols after swelling of modified starch in the dispersion medium up to the balance state. A degree of substitution of the discrete submicro-, nanoparticles of the modified starch flocculant according to cationic groups is from 0.15 to 0.28, accessibility of its cationic groups for polyanions is between 15 and 40 percent.

Description

Field of the Invention

The present invention relates to the preparation and use of starch derivatives in the art. Cationic starch derivatives are promising flocculants for water treatment and municipal sewage sludge dewatering because they are made from cheap, biodegradable and naturally renewable raw materials. In addition, they are non-toxic and biocompatible.

BACKGROUND OF THE INVENTION

The destabilization of dispersion systems in biotechnology, metallurgy, mining, water treatment, food and pharmaceutical industries is done to separate the solid phase from the liquid. In these applications, high degree of substitution (PL) by cationic starch (DKK) may be used. The paper used low-grade cationic starch (MCC), which contains a small amount of quaternary ammonium groups (H. ^ 0.1). The efficiency of cationic starch depends on the amount of cationic groups, molecular weight and state of the polyelectrolyte.

Preparation of a working gelatinized starch flocculant [soluble MKK [Thomas D.J., Atwell W.A. Starches. Eagan Press Handbook Series 0-891127-01-2, 1999, p. 94] jj is usually dispersed in hot water or steam-jet cooked. There are also simpler methods of chemical-mechanical dispersion of starch and MCC [US4579944, et al.]. Here, a stable suspension of starch or its derivatives is obtained by exposure to aqueous polysaccharide suspensions in which NaOH solution has been added by shaking at room temperature for several minutes to several hours and then neutralizing the alkali.

In the manufacture of paper, the use of cross-linked MCCs [WO2012076163; WO02006007045; EP1061086; WO9746591; CN102796202], grafted and cross-linked starch copolymers [EP1452552 et al.] Or ampholytic cross-linked starch [US5523339]. The technological properties of their aqueous suspensions are not only determined by the chemical composition of the target additive [EP1452552; EP0603727], the nature of starch used in the manufacture of a product [V002006007045; EP0139597] but also the state of the modified polysaccharide after dispersion, which is determined by the number of covalent bonds between the macromolecules and the method of preparation of the modified starch suspensions. For example, EP0603727 states that by increasing the amount of the crosslinking agent epichlorohydrin, the viscosity of the product's paste under jet cooked is reduced by up to 85 percent. from baseline. Optimal conditions for chemical modification of starch with cationic, crosslinking agents and pasteurisation [W00214602] provide the desired size microparticle product and viscosity crosslinked MCC starch suspension [EP1061086], which improves the quality and production process of paper forming.

The use of a cross-linked aqueous suspension of MCCs in the manufacture of paper is known [W00208516]. The slurry is obtained by dispersing shear-strength MKK in aqueous solution of hydroxy-containing compounds mixed with 0.01 to 7% by weight of a crosslinking agent. Such treatment results in discrete crosslinked MCCs with a degree of substitution of no more than 0.1 per cationic group. The resulting suspension, when incorporated into the papermaking pulp, improves the retention of ingredients in the pulp and the strength of the dry state paper. However, soluble MCC or cross-linked MCC have too low a positive sign charge density to be effective in drinking water treatment, municipal sewage sludge compaction or drainage processes.

In water treatment, the flocculant may have a high degree of substitution cationic starch (DKK) when its degree of substitution of hydroxy groups by cationic substituents is greater than 0.1. DKK flocculants are obtained by a one-step etherification process by the action of glycidyltrimethylammonium chloride (GTAC) on organic starch in the presence of organic or inorganic bases. This reaction produces cationic starch, N- (2-hydroxy) propyl-3-trimethylammonium starch chloride. In this case, the aqueous suspension of flocculant from the cationic starch, after removal of the reactant residues, prepares the microgranular cationic starch by stirring in water at 20-60 ° C for one hour and then maintaining it for 8-24 hours at room temperature [Bratskaya S. Effect of Polyelectrolyte Structural Properties on Flocculation Behavior: Cationic Polysaccharides vs. Synthetic Polycations // Schwarz S., Laube T., Liebert T., Heinze T., Krentz O.// Macromolecular Materials and Engineering. 2005, vol. 290, pp. 778-785; Šablevičienė D., Klimavičiūtė R., Bendoraitienė J., Žemaitaitis A. Flocculation Properties of High-Substituted Cationic Starches // Colloids and Surfaces A:

Physicochemical and Engineering Aspects. ISSN 0927-7757. 2005, vol. 259, p. 2330]. In the latter case, the flocculant is obtained by purifying the cationic starch after the etherification reaction with impurities by stirring in water at 20 ° C for one hour and then maintaining the suspension for 8 hours at room temperature or further dispersion in an autoclave at 126 ° C for at least 30 minutes. The flocculation efficiency of N- (2-hydroxy) propyl-3-trimethylammonium starch chloride is enhanced by dispersing the cationic starch in a solution of divalent cations or in seawater [WO2004041732]. Shear-dispersed starch etherification mixture containing DKK achieves N-(2-hydroxy) propyl-3-trimethylammonium groups with a DKK availability of at least 73 percent after reaction in hydrogen peroxide solution [Lithuanian patent LT5926]. However, the flocculation window of the dispersed shear-soluble DKK flocculant is significantly reduced (Figure 1, curve 1) and it is difficult to maintain a stable flocculation process.

The properties of DKK flocculant are changed by crosslinking its macromolecules. Crosslinked DKK can be obtained by graft copolymerization [CN 102898666] or by reaction between cationic starch and crosslinking agents on difunctional epoxides, dialdehydes, triazine and N-methylol derivatives, epichlorohydrin [CN101700922],

Crosslinked DKK flocculants according to CN101700922 are obtained by reacting starch with cationic group reagents and crosslinking agents simultaneously or by cationization of crosslinked starch. It uses epichlorohydrin, difunctional epoxides, aldehydes, triazine and N-methylol compounds for crosslinking. In this way, the undispersed modified starch becomes an environmentally friendly flocculant capable of combining soluble anionic dyes. According to the invention, at least 0.02% (0.04 mol / AGL) epichlorohydrin is used in the manufacture of the crosslinked DKK. Therefore, shear dispersions of such crosslinked DKK cannot achieve a cationic group availability of greater than 15 percent and provide an effective flocculant suitable for water treatment.

There is a known way to obtain high degree of substitution of cationic groups, crosslinked ampholytic polysaccharide from tapioca starch [CN 102898666]. The synthesis is carried out by attaching dimethylallylammonium chloride, acrylic acid or a derivative thereof to starch macromolecules and crosslinking with difunctional reagents, drying and grinding. The resulting macromolecular material of ampholytic properties is resistant to acids, heat and shear. Due to the latter property, such cationic starch has low flocculation efficiency.

The aforementioned cross-linked DKK products cannot be dispersed by shear forces to such an extent that their amount of cationic groups available to polyanions exceeds 15 percent of the total due to the high amount of crosslinking. As a result, their use in flocculant separation processes for dispersed solids increases at least several times.

For water treatment and purification - surface water, wastewater treatment, and sludge treatment, it is useful to use a flocculant with a small amount to cause rapid and complete destabilization of the aqueous suspension and to begin later with as much flocculant as possible. Such a flocculant would have a wide flocculation window. The larger the flocculation window, the lower the risk of solid, including contaminant, particle restabilisation, and the safer separation process. Flocculant with such properties would be able to flocculate both dilute and concentrated suspensions with varying particle sizes, reduce the influence of process factors such as suspension pH, ionic strength, solids concentration and particle size changes, and destabilize the dispersed systems themselves. In addition, flocculants that expand not only the solids of the pollutants but also bind water-soluble anionic substances (detergents, dyes, stabilizers, etc.) are needed to expand the applicability of flocculants. Then, after flocculation, cleaner water is obtained.

In this specification, the structure of cationic starch flocculants is characterized by the amount (degree of substitution) of cationic groups in PL and their availability to polyanions - P. The quality of starch flocculants is characterized by a minimum amount of flocculant C (thousands of flocculant per unit weight of disperse phase) destabilization of the suspension to 10% residual turbidity (LD) and flocculation window width (W) occurs. W (flocculation window) is defined as the difference between the maximum and minimum content (C) of the cross-linked cationic starch having a residual turbidity (LD) less than 10%. The value of W is expressed in terms of thousands of parts by weight of cross-linked cationic starch per unit weight of the disperse phase. The higher the W, the lower the risk of re-suspension of the suspension particles and the safer the process of separating solids from the liquid.

It is an object of the present invention to provide an effective cationic starch flocculant for water treatment comprising:

(a) a wide window of flocculation at low levels of starch flocculant;

(b) having a higher ability to bind soluble anions (such as dyes, pharmaceutical residues, heavy metals, especially chromium anion salts, etc.).

The use of a flocculant with such properties would reduce the influence of process factors such as pH, ionic strength, solids concentration and particle size changes on the dispersion system, stabilize the suspension suspension process, and eliminate soluble anionic contaminants during suspension flocculation.

The essence of the invention

To achieve the object of the invention there is provided a novel modified starch flocculant based on cationic starch dispersed in shear, wherein said modified starch is a discrete particle crosslinked cationic starch capable of binding soluble anionic pollutants and having a degree of substitution of at least 0.1 to 0.15, , 28, the availability of cationic groups for polyanions from 15% to 40% and a wide flocculation window, wherein the flocculation window is the difference between the maximum and minimum amount of flocculant required to destabilize the suspension to 10% residual turbidity.

More particularly, the flocculant according to the invention is characterized in that, when the degree of substitution of the modified starch by cationic groups is at least 0.15, the flocculation window is not less than 35 parts by weight of flocculant per thousand parts by weight of the dispersed phase. Said modified starch is a cross-linked N- (2-hydroxy) propyl-3-trimethylammonium starch chloride not larger than submicron particles. The starch is selected from the group consisting of potato, tapioca, wheat, corn, rice starch, optimally potato starch.

The modified starch flocculant according to the invention is for use in water treatment.

Another object of the invention is a dispersion system comprising a modified starch flocculant and a dispersion medium; the dispersion system contains from 1% to 50% of said modified starch, and its dispersion medium is water or a mixture of water with polyhydric alcohols such as ethanediol, glycerol, maltose, sorbitol.

One embodiment of the present invention is said dispersion system in the form of a paste in which the amount of modified starch is preferably 15-40%.

The process for producing the flocculant of the invention comprises the steps of cationization and shear dispersion of starch; it differs in that it undergoes starch cross-linking during the process.

According to the present invention, starch crosslinking to obtain a flocculant is carried out prior to cationization, during cationization, or during shear dispersion, at the following molar ratio of components: Starch anhydroglucoside residue (AGL): Crosslinking agent (TA): Cationization agent (KA): Base: , 1: (0.0005-0.005): (0.17-0.40): (0.006-0.048): (3.5-10).

For the flocculant according to the invention, the starch or cationic starch is crosslinked in an alkaline medium with a crosslinking agent selected from the group consisting of epichlorohydrin, phosphates, difunctional epoxides, aldehydes, triazines, N-methylol derivatives.

Shear dispersion in accordance with the present invention is carried out by grinding, rubbing and / or extruding cross-linked cationic starch in a dispersion medium. In the preferred embodiment, the shear dispersion is carried out by swelling the cross-linked cationic starch in the dispersion medium to an equilibrium state.

Brief description of the drawing

BRIEF DESCRIPTION OF THE DRAWINGS The drawing illustrates the dependence of the residual turbidity (LD) of a flocculated kaolin suspension on the amount of cationic starch flocculant added (mg / gcaine): 1- Dispersed with shear-soluble cationic starch = PL = 0,20 flocculent = flocculent. % (Description Example 6); 2 is a shear-dispersed flocculant cationic starch flocculant according to the present invention PL = 0.19 and P = 29% (Example 1 description); 3 - Non-dispersible shear-soluble cationic starch flocculant with PL = Q, 2Q and P = 18% (Example 6 description).

Detailed Description of the Invention

As mentioned above, the main object of the invention is an effective crosslinked DKK flocculant (Table 1), which settles the suspension particles over a wide range of crosslinked DKK (with a wide flocculation window, I / V) and, additionally, removes soluble anionic substances from the suspension. This is achieved by etherification of potato, tapioca or cereal starch microgranules such as glycidyltrimethylammonium chloride (GTAC) by attaching 0.15 to 0.28 moles of GTAC to the starch anhydroglucosidic residue (AGL) and cross-linking the polysaccharide with difunctional crosslinking agents or in two steps (scheme below) and then dispersing it in shear in a dispersion medium until 15 to 40 percent of the N- (2-hydroxy) propyl-3-trimethylammonium (cationic) groups available on polyanions appear in the crosslinked cationic starch. The dispersed discrete cross-linked cationic starch has submicronic, nanoparticle size less than 10 µm, preferably about 1 µm.

table

Quality Indicators of Effective Cross-linked DKK Flocculant

Flocculation window W > 35 Minimum amount required C, mg / gkaoin <15 Availability of cationic groups to polyanions P,% 15-40

General scheme of DKK single- and two-stage synthesis:

R = -H or -CH ₂ -CH (OH) -CH ₂ -N ⁺ (CH ₃ ) 3 Cl '

As can be seen from the above synthesis scheme, in all cases, the crosslinked cationic starch is obtained which is dispersed by shear during or after synthesis. The cross-linked cationic starch can be obtained by a one-step etherification of natural starch (including potato, wheat, tapioca, corn, rice) with a cationization agent such as glycidyltrimethylammonium chloride or other, and a crosslinking agent such as epichlorohydrin or phosphate, , aldehyde, triazine N-methylol groups, etc. In the preparation of the crosslinked cationic starch, the cationic starch is first obtained in a two-step manner, after which it is crosslinked with the selected crosslinking agent or etherified with the cationic starch.

For the preparation of crosslinked DKK microparticles, a one-step etherification mixture is prepared by mixing a solution of NaOH or another base (e.g., benzyltrimethylammonium hydroxide) with glycidyltrimethylammonium chloride (GTAC) by adding the crosslinking agent (TA) (epichlorohydrin (EPI) or other, e.g. (STMP)), air dry the natural starch and mix thoroughly. The molar ratio of reactants in the heterogeneous reaction mixture 1 - AGL Crack: TA: GTAC: Base: H2O = 1: (0.0005-0.00065): (0.17-0.35): (0.04-0.048): (3 , 5-4.6). The reaction is carried out at 30-55 ° C for 56-20 hours.

In the manufacture of crosslinked microparticles, DKK first produces crosslinked starch and then cations. The cross-linked starch is obtained by adding 50% aqueous potato starch slurry in an emulsion of epichlorohydrin (EPI) emulsified in a water-alkali mixture and mixing well at room temperature with a magnetic stirrer. The molar ratio of reactants in the heterogeneous mixture is 2 - AGL: EPI: NaOH: H2O = 1: 0.005: 0.006: 10. The reaction is carried out at 30-55 ° C for 56-20 hours. Cationization is carried out by etherification of cross-linked starches such as glycidyltrimethylammonium chloride (GTAC) in an alkaline medium. To obtain the crosslinked DKK, the etherification mixture is prepared by mixing the NaOH solution with GTAC, adding cross-linked starch to the mixture and mixing the components thoroughly. Mole ratio of reactants in heterogeneous mixture 3 - AGL: GTAC: NaOH: H2O = 1: 0.40: 0.044: 3.15. The reaction is carried out in a heterogeneous medium at 30-55 ° C for 56-20 hours.

From the crosslinked DKK, the DKK particles are ground, rubbed and / or extruded in a dispersion medium (e.g. water or in a mixture of water and a multifunctional alcohol such as ethanediol, glycerol, sorbitol) to form a suspension of flocculant. shear forces would be applied. For example, 1% crosslinked DKK disperses the aqueous suspension with a Digital UltraTurrax T25 dispersant at 15000 rpm for 10 to 30 minutes.

In one embodiment of the invention, the cross-linked starch gel is further allowed to swell to equilibrium swelling prior to dispersion, for example, by maintaining the gel for 30-60 minutes at room temperature. Upon maximum swelling, the flocculant particles of the present invention exhibit reduced polydispersity.

Dispersing said crosslinked DKK provides extruded dispersion systems containing, for example, 30-40% modified starch flocculant according to the invention. Such pastes can be described by measuring the mechanical workload (J) per gram of cross-linked DKK used in their production. The mechanical work performed to produce the flocculant according to the invention by extrusion has a value of from 0.1 kJ / g to 0.5 kJ / gnocyanate.

By characterizing the flocculant, it analyzes the amount of cationic groups in the network

DKK (PL) and their availability (P,%) to dextran sulfate (DeSu), evaluate flocculant efficacy against suspension residual turbidity (LD,%) as determined by the light absorption of model kaolin or real suspensions after flocculation (turbidimetric suspension studies). Methods for determining these properties are generally known and described in patent LT5926.

According to the above methodology, the cationic content of modified starch is calculated as the degree of substitution (PL) according to formula (1):

PL =

162-N

1400-151,5-N '(1) where N,% is the nitrogen content of the sample, 162 is the mass of starch anhydroglucosidic residue (AGL).

The amount of cationic groups (Aoesu) linked to the polyanions (DeSu) in g-equiv / g is calculated by the formula (2):

DeSu (2) where: V is the volume, in ml, of DeSu used for the titration; N - DeSu concentration, g / ml; m is the quantity of cationic starch in the volume of the solution used for the analysis, g.

The percentage of available cationic groups (P) in the cationic starch is calculated by the formula (3):

L DeSu \ FLazoto J • 100;

(3) Here: amount of Auesu-DeSu-linked quaternary ammonium groups, g-eq / g; Azototal quaternary ammonium content determined by the Kjeldahl method, g-eq / g.

To determine the flocculant efficacy / efficacy of the flocculant, a finely dispersed kaolin derived from Sigma-Aldrich (USA) is used. Geometric mean of kaolin particle diameter calculated from particle size distribution curves (Delsa ™ Nano C, Beckman Coulter, USA), 0.7-0.85 pm.

The kaolin suspension is prepared by ultrasonication for 15 minutes of an aqueous suspension of 1 g / l of finely dispersed kaolin.

Kaolin suspension destabilization: The kaolin suspension destabilization experiment is conducted at room temperature. add to the beaker 50 ml of the prepared kaolin slurry, stirring with a magnetic stirrer, adding the necessary amount of flocculant and mixing. The suspensions are then allowed to settle in two fractions and the light absorption of the supernatant fraction is measured at 500 nm with a UNICAM UV3 UV / Vis spectrophotometer. Calculate the residual turbidity (LD) using the formula (4):

LD =

A500 _f

A500 _p

100% (4) where: A500f - suspension to absorb light at 500 nm, followed by insertion of the flocculating agent, _P. A500 - Initial synthetic suspension in light absorption at 500 nm.

The effective amount of cationic cross-linked starch C is calculated as the minimum amount of added cationic starch in mg / g of the dispersed phase with a residual turbidity (LD) of 10%.

Flocculation of a suspension containing kaolin in addition to acid blue dye (Acid Blue 25) determines the residual color of the suspension. It is calculated in the same way as residual turbidity, except that the light absorption of the suspension is measured at 600 nm.

Examples of implementation of the invention

The invention is illustrated by the following examples. This information is provided for illustrative purposes only and is not intended to limit the scope of the invention.

example

The crosslinked DKK was obtained by one-step etherification of potato starch with glycidyltrimethylammonium chloride (GTAC) and epichlorohydrin (EPI) in alkaline medium. The etherification mixture was prepared by mixing NaOH solution with GTAC and EPI by adding starch to such mixture and mixing the components thoroughly. The molar ratio of reactants in the mixture was AGL: EPI: GTAC: NaOH: H2O = 1: 0.0005: 0.22: 0.04: 3.5. The reaction was carried out at 45 ° C for 48 hours. The degree of substitution of the resulting product was PL = 0.19, and the availability of cationic groups to polyanions (P) was 4%. Flocculation window W = 362, minimum required cationic starch content C = 138 mg / gkaoin.

For the preparation of a cationic starch flocculant, a 1% aqueous suspension of the product was shear-dispersed at room temperature in a Digital Ultra-Turrax T25 dispersant at 15000 rpm for 20 minutes. The cationic group availability of cationic starch for polyanions (P) after dispersion was 29%. Flocculation window I4A = 49, C = 15 mg / gkaoin.

example

The crosslinked MCC and the flocculant were prepared as in Example 1 except that the molar ratio of reactants in the mixture was AGL: EPI: GTAC: NaOH: H2O = 1: 0.0005: 0.11: 0.04: 3.5. The degree of substitution of the resulting cross-linked MCC is PL = 0.10. After dispersion, the cationic starch (P) availability of the cationic crosslinked cationic starch was 85%, W = 21, C = 9 mg / gkaoin.

example

The crosslinked DKK and its flocculant were prepared as in the first example, only the molar ratio of reactants in the mixture was AGL: EPI: GTAC: NaOH: H2O = 1: 0.0005: 0.17: 0.04: 3.5. The resulting net DKK substitution degree is PL = 0.15. After dispersion, the cationic groups (P) availability of cationic crosslinked cationic starch was 15.5%, l / V = 35, C = 15 mg / gkaoin.

example

The crosslinked DKK and its flocculant were prepared as in the first example, except that the molar ratio of reactants in the mixture was AGL: EPI: GTAC: NaOH: H2O = 1: 0.0005: 0.33: 0.04: 3.5. The resulting cross-linked DKK has a degree of substitution of PL = 0.28. After dispersion, the cationic starch (P) availability of the cationic crosslinked cationic starch was 18%, 1/1 / = 49, C = 14 mg / gkaoin.

example

The crosslinked DKK and its flocculant were prepared as in the first example, except that the molar ratio of reactants in the mixture was AGL: EPI: GTAC: NaOH: H2O = 1: 0.0005: 0.44: 0.04: 3.5. The resulting cross-linked DKK has a degree of substitution of PL = 0.39. After dispersion, the cationic groups (P) availability of cationic crosslinked cationic starch was 25%, 14 / = 26, C = 9 mg / gkaoin.

example

Soluble DKK was prepared as the cross-linked DKK in Example 1, except that epichlorohydrin was not added to the reaction mixture. The degree of substitution of the resulting DKK was 0.20, the availability of cationic groups for polyanions (P) was 18%, 14 / = 36, C = 28 mg / gkaoin.

In the manufacture of DKK flocculant, the DKK paste was dispersed at room temperature by shear force to a 1% solution of opalescent flocculant in a Digital Ultra-Turrax T25 dispersant at 15,000 rpm for 15 minutes. The cationic groups availability of soluble cationic starch for polyanions (P) after dispersion was 77%, 14 / = 8, C = 2 mg / gkaoin.

sample (comparative, according to patent CN101700922)

The crosslinked DKK was prepared as in Example 1 except that the molar ratio of reactants in the mixture was AGL: EPI: GTAC: NaOH: H2O = 1: 0.01: 0.22: 0.05: 3.5. The resulting net DKK substitution degree is PL = 0.19.

The volatile DKK flocculant was produced as in the first example. The availability of cationic groups of cationic starch on polyanions (P) after dispersion was 1.4%, 1/1 / == 2380, C = 380 mg / gkaoin.

example (comparative, with known synthetic cationic flocculants)

The polyacrylamide synthetic soluble cationic flocculant, poly (acrylamide-coΝ, Ν, Ν, -trimethylammonium-ethyl acrylate) chloride, was dissolved in water and its 0.1% aqueous solution was used to flocculate the kaolin suspension. The availability of cationic groups for polyanions (P) was 100%, l / V = 7, C = 1.2 mg / gkaoin.

The second table shows the C and W values of MKK (Example 2), DKK (Examples 1, 3-7), and Synthetic Cationic (Example 8) flocculants. Analyzing the effectiveness of varying degrees of substitution by starch flocculants in clarifying kaolin suspensions shows that a flocculation window of greater than W = 35 at the required minimum level of cross-linked cationic starch C of 15 mg / gkaine or less the cationic groups are from 0.15 to 0.28 shear-treated particles. It is also apparent from the data in Figure and Table 2 that only DKK flocculants with optimal cationic group availability (P) flocculated the suspension particles efficiently. This quality is matched by DKK with PLo. 15-0.30 obtained after mechanical treatment with shear according to the invention such that 15 to 40 percent of the cationic groups available for polyanions are formed in its particles. Outside the indicated availability of cationic starch PL or its flocculant, the flocculation effect was worse.

table

For example N r. PL P,% Flocculant efficiency c, mg / gkaolin W 6 * 0.20 18th 28th 36 6th 0.20 77 2 8th 1 * 0.19 4 139 362 2 0.10 85 9th 21st 3 0.15 15.5 15th 35 1 0.19 29th 15th 49 4 0.28 18th 14th 49 5 0.39 25th 9th 26th 7th 0.19 1.4 380 2380 8th - 100 1.2 7th

* undissolved shear-strength DKK sample

The customized DKK was produced as in the first example. A 15% aqueous slurry of the product at room temperature was shear-dispersed in a Philips 700 W power mixer at 5 speeds for 4 minutes to produce a cationic starch flocculant. The availability of cationic groups of cross-linked cationic starch to polyanions (P) after dispersion was 29%, W = 40, C = 10 mg / gkaoin.

example

The crosslinked DKK was obtained by etherification of potato starch with glycidyltrimethylammonium chloride (GTAC) in alkaline medium and addition of sodium trimetaphosphate (STMP) to the reaction mixture. The etherification mixture was prepared by mixing STMP dissolved in water with GTAC and NaOH solution, adding starch to such mixture and mixing the components thoroughly. The molar ratio of reactants in the mixture was AGL: STMP: GTAC: NaOH: H2O = 1: 0.00065: 0.33: 0.048: 4.6. The reaction was carried out under heterogeneous conditions at 55 ° C for 20 hours. The resulting cross-linked DKK has a degree of substitution of PL = 0.28.

During the manufacture of the crosslinked DKK flocculant, a 1% aqueous suspension of the product was dispersed at room temperature by shear force in a Digital Ultra-Turrax T25 dispersant at 15000 rpm for 10 minutes. The cationic group availability of cationic starch cationic groups (P) after dispersion was 23%, W = 51, C = 15 mg / gkaolin sample

The crosslinked DKK was obtained by single-stage etherification of wheat starch with glycidyltrimethylammonium chloride (GTAC) and epichlorohydrin (EPI) in alkaline medium. The etherification mixture was prepared by mixing the NaOH solution with GTAC and EPI by adding starch to the mixture and mixing the components thoroughly. The molar ratio of reactants in the mixture was AGL: EPI: GTAC: NaOH: H2O = 1: 0.0005: 0.22: 0.04: 3.5. The reaction was carried out under heterogeneous conditions at 45 ° C for 48 hours. The resulting net DKK substitution degree is PL = 0.19.

The volatile DKK flocculant was produced as in the tenth sample. The availability of cationic groups of crosslinked cationic starch on polyanions (P) after dispersion was 29%, Ι / Ιλ = 37, C = 11 mg / gkaoin.

example

The crosslinked DKK is made in a two-step process: the first is the crosslinked starch, by adding 50% aqueous potato starch slurry in an emulsion of epichlorohydrin (EPI) and mixing well at room temperature with a magnetic stirrer. The molar ratio of reactants in the mixture was AGL: EPI: NaOH: H2O = 1: 0.005: 0.006: 10. The reaction was carried out at 45 ° C for 48 hours. The cross-linked DKK is obtained by etherification of the cross-linked starch with glycidyltrimethylammonium chloride (GTAC) in alkaline medium. The etherification mixture was prepared by mixing the NaOH solution with GTAC by adding the cross-linked starch and mixing the components thoroughly. The molar ratio of reactants in the mixture was AGL: GTAC: NaOH: H2O = 1: 0.40: 0.044: 3.15. The reaction was carried out under heterogeneous conditions at 45 ° C for 48 hours. The resulting cross-linked DKK has a degree of substitution of PL = 0.28.

For the manufacture of crosslinked DKK flocculant, a 1% aqueous suspension of the product was dispersed at room temperature by shear force with a Digital Ultra-Turrax T25 dispersant at 15000 rpm for 25 minutes. The cationic group availability of cationic starch cationic groups (P) after dispersion was 20%, 14 ^ = 35, C = 15 mg / gkaoin.

An effective flocculant can be prepared by a variety of one and two step processes (Table 3) by etherification of starch (Examples 1 and 12) using various crosslinking agents (Example 10) and botanical (Example 11) feedstock by dispersing high concentrations of DKK suspensions (Example 9).

table

For example No. PL P,% Flocculant efficiency C, mg / kgcoin W 1 0.19 29th 15th 49 9th 0.19 29th 10th 40 10th 0.28 23rd 15th 51 11th 0.19 29th 11th 37 12th 0.28 20th 15th 35

example

Polyacrylamide synthetic soluble cationic flocculant - poly (acrylamide-coΝ, Ν, Ν, -trimethylammonium-ethyl acrylate) chloride was dissolved in water as in the eighth sample and its 0.1% aqueous solution was used in 0.3% methantane sludge (UAB Kauno vandenys ) in the tanker. Flocculant Flocculation Window W = 36, C = 2 mg / g dispersion phase.

example

The cross-linked DKK and its flocculant were produced as in the ninth sample and were used in 0.3% thickening of methant tank water treatment sludge (Kauno vandenys UAB). The cross-linked cationic starch has 1 // = 58, C = 5 mg / g dispersion phase.

example

Polyacrylamide synthetic soluble cationic flocculant, poly (acrylamide-coΝ, Ν, Ν, -trimethylammonium-ethyl acrylate) chloride, was dissolved in water as in the eighth sample and its 0.1% aqueous solution was used in a suspension of kaolin.

0.01 g / l in flocculation of acid blue dye (Acid Blue 25). Flocculant W = 5.5, C = 5 mg / gcoin. The residual color of the clarified suspension (filtrate) was 16%.

example

The preparation and dispersion of the crosslinked MCC by shear were performed as in the second example. Flocculation was performed according to the procedure, only 0.01 g / l acid blue dye (Acid Blue 25) was added to the kaolin suspension. The product did not effectively flocculate the kaolin suspension with the dye because the residual turbidity was greater than 10% and the filtrate had a residual color of 12%.

example

The preparation and dispersion of the crosslinked DKK by shear were performed as in the first example. Flocculation was carried out as described in the procedure, only 0.01 g / l acid blue dye (Acid Blue 25) was added to the kaolin suspension. The cross-linked cationic starch had W = 72, C = 24 mg / gkaoin, and the filtrate had a residual color of 2%.

table

For example: yeah No. PL P,% Compaction of methantane sludge Flocculation of kaolin suspensions with dye C, mg / g W C, mg / gkaolin W Residual color,% 13th - 100 2 36 - - - 14th 0.19 29th 5 58 - - - 15th - 100 - - 5 5.5 16th 16th 0.10 85 - - ★ * 12th 17th 0.19 29th - - 24th 72 2

* ineffective - residual turbidity greater than 10% after flocculation

Cross-linked MCCs, DKKs and synthetic cationic flocculants were tested in methantane sludge thickening and in the flocculation of kaolin suspensions with Acid Blue 25. The data in Table 4 show that the minimum amount of cross-linked DKK required for compaction of the metantanking sludge is, however, that the window of flocculation is much wider than that of the industrial synthetic cationic flocculant. In the kaolin suspension, the water-soluble dye flocculant from MCC was ineffective (Example 16), the synthetic cationic flocculant flocculated efficiently but with a narrow flocculation window (Example 15) and bound less dye than the cross-linked DKK flocculant. The latter exhibited excellent flocculation of the kaolin suspension with dyes in a wide flocculation window (Example 17) and well bound dye.

example

The crosslinked DKK and its flocculant were prepared as in the first example, using only benzyltrimethylammonium hydroxide (BTMAOH) as catalyst and the molar ratio of reactants in the mixture was AGL: EPI: GTAC: BTMAOH: H2O = 1: 0.0005: 0.35: 0.04 : 3.5. The reaction was carried out under heterogeneous conditions at 30 ° C for 56 hours. The resulting cross-linked DKK has a degree of substitution of PL = 0.28. After dispersion, the cationic groups (P) availability of cationic crosslinked cationic starch was 19%, MA = 48, C = 15 mg / gkaoin.

In summary, the present invention has the following main advantages over the prior art:

1) efficiently flocculates suspensions with a wide flocculation window;

2) binds soluble anionic pollutants contained therein effectively by flocculating the suspensions.

Industrial applicability

From the experimental data presented in Examples 1-18 of the present invention, it can be concluded that the flocculants of the invention can be used effectively in water treatment - water, wastewater treatment and sludge treatment by separating solids and water soluble anionic pollutants , ionic strength, solids concentration and their particle size process.

Claims (12)

1. Modified starch flocculant based on cationic starch dispersed in shear, characterized in that said modified starch is a discrete particle cross-linked cationic starch, capable of binding soluble anionic pollutants and having a degree of substitution of at least 0.1 to 0.15, , 28, availability of cationic groups for polyanions from 15% to 40% and a wide flocculation window, wherein the flocculation window is the difference between the maximum and minimum amount of flocculant required to destabilize the suspension to 10% residual turbidity. 2. The modified starch flocculant of claim 1, wherein the degree of substitution of the modified starch by at least 0.15 by cationic groups has a flocculation window of at least 35 parts by weight of flocculant per thousand parts by weight of the dispersed phase. Modified starch flocculant according to claim 1 or 2, characterized in that the modified starch is a cross-linked N- (2-hydroxy) propyl-3-trimethylammonium starch chloride not larger than submicron particles. The modified starch flocculant according to any one of claims 1 to 3, characterized in that the starch is selected from the group consisting of potato, tapioca, wheat, corn, rice starch, preferably potato starch. Modified starch flocculant according to any one of claims 1 to 4 for use in water treatment. A dispersion system comprising a modified starch flocculant according to any one of claims 1 to 5 and a dispersion medium characterized in that it contains 1-50% of said modified starch and the dispersion medium is water or a mixture of water with polyhydric alcohols such as ethanediol, glycerol, maltose, sorbitol. 7. The dispersion system of claim 6 in the form of a paste, wherein the modified starch is preferably present in an amount of 15-40%. A process for the preparation of a modified starch flocculant according to any one of claims 1 to 5, comprising the steps of cationization and shear dispersion of the starch, characterized in that the starch is crosslinked during the process. 9. A process for the preparation of a modified starch flocculant according to claim 8, wherein the starch crosslinking is carried out prior to cationization, during cationization or during shear dispersion, at the following molar ratio of components: Starch anhydroglucoside residue (AGL): crosslinking agent (TA): (KA): Base: water, optimally, 1: (0.0005-0.005): (0.17-0.40): (0.006-0.048): (3.5-10). Process for the manufacture of a modified starch flocculant according to claim 8 or 9, characterized in that the starch or cationic starch is crosslinked in an alkaline medium with a crosslinking agent selected from the group consisting of epichlorohydrin, phosphates, difunctional epoxides, aldehydes, triazines. 11. A process for the manufacture of a modified starch flocculant as claimed in any one of claims 8 to 10, wherein the shear dispersion is carried out by grinding, rubbing and / or extruding cross-linked cationic starch in a dispersion medium. 12. A process for the manufacture of a modified starch flocculant according to any one of claims 8 to 11, wherein the shear dispersion is carried out after the crosslinking of the cationic starch in the dispersion medium to an equilibrium state.