LT5926B - Cationic starch flocculant and the method of production thereof - Google Patents

Abstract

The invention relates to the field of chemistry and can be used to produce the cationic flocculants from starch for industrial and municipal wastewater and sludge processing. The way to obtain the cationic starch flocculants with high accessibility of N-(2-hydroxy)propyl-3-trimethylammonium groups to polyanions includes etherification of starch microgranules with glycidyltrimethylammonium chloride and dispergation of mixture consisted of etherification reaction mixture and solution of hydrogen peroxide at room temperature by shearing force.

Description

The present invention relates to the field of chemistry and can be used in industrial and municipal wastewater and sewage sludge processing - compaction and drainage processes.

High molecular weight water soluble polyelectrolytes interact with dispersions, including wastewater and sludge pollutants, to aggregate them and facilitate separation from the aqueous phase during sedimentation, filtration, or centrifugation. The main raw material for synthetic flocculants is water-soluble synthetic polyacrylamide and its ionogenic derivatives. Flocculants may also be ionogenic derivatives of natural polysaccharides such as cellulose, chitin, and starch. For example, carboxymethyl starch sodium salts are used as flocculants in the oil industry [B.H. KpaaceB *, B.B. Ρομβηοβ, B.A. ΜηροκοΒ, nOCJIE / AHHE / ĮOCTFDKEHHH ΧΗΜΗΗ H ΤΕΧΗΟΙΊΟΓΗΗ nPOH3BOJIHbIX KPAXMAJIA // ΧΙ4ΜΙ4Ή PACTHTEJJbHOTO CbIPbfi, 2010. N ° l. C. 5-12], Tannin [Ozacar M. Evaluation of tannin biopolymer as a coagulant aid in the coagulation of colloidal particles / Sengil A. // Colloids and Surfaces. A: Physicochem. Eng. Asp. 2003, vol. 229, p. 85-96], chitosan and cationic starch [Pat. 5543056, USA. TPKI C02F 001 / 56.1996] for the preparation of drinking water. It is proposed to use chitosan to combine humic acids in water [Bratskaja S. Comparative study of flocculation of humic acids with chitosan hydrochloride and chitosan glutamate / Schwarz S., Chervonetsky D. // Water Research. 2004, vol. 38, p. 2955-2961] as a flocculant for fat, protein removal in the meat and poultry processing industry [Pat. 5269939, United States. TPKI C02F 001/24. 1993],

Cationic starch derivatives are the most promising flocculants among polysaccharides in sludge recycling. They are made from cheap, biodegradable and naturally renewable raw materials, are non-toxic, biocompatible, and, after flocculation, have a distinctive structure of floccules in their dispersion. Their flocculation efficiency depends on the amount of cationic groups, molecular weight and state of the polyelectrolyte in the flocculant solution. The main method of attaching the ionic groups of the positive charge to starch macromolecules was and remains etherification with glycidyltrimetammonium chloride (GTAC) or its chlorohydrin in the presence of bases. Low grade (PL) cationic starch with low (PL <0.05-0.08) quaternary ammonium groups is used in paper making [Pat. 3346563, USA. TPKI C08B31 / 00. 1967; Pat. 3448101, United States. TPKI C08B19 / 06. 1969; Pat. No. 4281109, U.S.A. TPKI C08B31 / 08. C08B31 / 00. 1981], it is usually dispersed in boiling water when preparing a working flocculant solution. Simpler methods of dispersing chemical-mechanical starch and its derivatives, including low-degree cationic starch, are known [Pat 4279658, USA, TPKI

C08L 3/00, 1981; Pat. 4579944, US, TPKI C08B 31/00, 1986], provides stable dispersions of starch or its derivatives by the action of aqueous polysaccharide dispersions containing NaOH solution under shear at room temperature for several tens of minutes to several hours. Unfortunately, such a simple and efficient solution preparation method is not suitable for obtaining flocculants from high degree of cationic starch due to the high alkalinity of the dispersion or the low molecular weight electrolyte after neutralization with NaOH, since the remaining additives reduce the flocculant efficiency.

A high degree of substitution (O, 1 <PL <1) cationic starch is recommended for compaction and drying of sludge. Various cationization reagents and methods for preparing a working flocculant solution (s) are used to obtain such flocculants. The production of a soluble cationic starch flocculant involves multistep modification of the starch by initially attaching propionamide groups by reaction with acrylamide or methacrylamide to remove reactant residues, followed by aminomethylation with a mixture of formaldehyde and tertiary amines [Pat 3823100, U.S. Pat. a starch flocculant is obtained when the starch is oxidized with hypochlorite, dissolved in open steam and etherified with an amino butene halide (e.g., l-chloro-4-butenyltrimethylammonium chloride) [Pat 3835114, US, TPKI C08b 19/06, 1974; Pat 3875054, US, TPKI BOld 21/01, 1975]. The same result is obtained when the oxidation of the hypochlorite before the cationization with the amino butene halide is replaced by the destruction of the crude starch with hydrogen chloride [Pat 3962079, USA, TPKI C08B 31/12, 1976].

High-replacement cationic starches are also obtained by the single-step cationization GTAC. In this case, an aqueous dispersion of a cationic starch flocculant, after removal of the reactant residues, is prepared by stirring the solid state cationic starch in water at 20-60 ° C for one hour and then maintaining it for 8-24 hours at room temperature [Bratskaya S. Cationic Polysaccharides vs. Synthetic Polycations / Schwarz S., Laube T., 3 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. 23-30],

The cationic starch flocculant preparation methods mentioned are multi-step and expensive because the cationic starch has to be cleaned several times from the residual solvents and reagents used and the cationic starch flocculant dispersion has a high thermal input.

The prototype of the present invention is a flocculant of N- (2-hydroxy) propyl-3-trimethylammonium starch chloride (CC) having a degree of substitution between cationic groups of 0.21 to 0.56 [Šablevičienė D., Klimavičiūtė R., Bendoraitienė J. , Samogitia A. Flocculation Properties of High-Substituted Cationic Starches // Colloids and Surfaces A: Physical Chemistry and Engineering Aspects. ISSN 0927-7757. 2005, vol. 259, p. 23-30], it is obtained after washing the ethereal reaction from impurities in KK by stirring in water at 20 ° C for one hour and then maintaining the dispersion for 8 hours at room temperature or further dispersion in an autoclave at 126 ° C for at least 30 minutes.

The object of the present invention is to increase the efficiency of flocculating N- (2-hydroxy) propyl-3-trimethylammonium starch chloride by dispersing a dispersion of the starch etherification mixture after reaction, hydrogen peroxide and water at room temperature under shear to the flocculant N- (2-hydroxy) propyl-3- availability of trimethylammonium groups becomes at least 73 percent. In the dispersion of shear-dispersible starch etherification mixture, the degree of substitution of the cationic starch in the reaction mixture, hydrogen peroxide and water in a ratio of 1: 0.01 to 0.02: 98.99-98.98 (parts by weight) is from 0.28 to 0.47.

Cationic starch is produced by etherification of natural starch in the form of microgranules with glycidyltrimethylammonium chloride (GTAC) in the presence of organic or inorganic bases (reaction equation).

+ ^cl [C ₆ H (OH ')] _u + CH ₂ -CH-CH ₂ N (CH ₂

\)

I

Cl [C ₆ Hp, (OHi _{5 χ} (O-CHj-HH-CH ^ NiCH ^]), OH where x = PL - N - (2-hydroxy) propyl-3-trimethylammonium groups content in the anhydroglucose residue (AGL).

The etherification mixture is prepared by mixing solutions of NaOH or organic base with GTAC, adding natural starch to the mixture and mixing thoroughly. Mole ratio of reactants in the reaction mixture AGLkrakmoitv GTAC: Base: H2O = 1: z: 0.04: w. Here, z and w, respectively, are the number of moles GTAC and water added to the reaction mixture. The reaction was carried out under heterogeneous conditions at 45 ° C for 24 h. After the reaction, 1 part of the resulting starch etherification mixture is added to 98.99-98.98 parts of water dissolved in 0.01-0.02 parts of hydrogen peroxide and dispersed at room temperature with a Digital Ultra-Turrax T25 dispersion at 15000 rpm. up to 15 minutes prior to the formation of an opalescent flocculant dispersion.

Analyzing cationic groups of KK and availability of dextran sulphate (desu), assessed flocculant effectiveness on the D _st index, which is determined by simulations kaolin dispersions light absorption after the kaolin dispersion flocculation KK flocculant (turbidimetric variances Research) and kaolin dispersions flocculation dynamic performance indicators DDI _n .

The finely dispersed (K _sm ) and coarse-dispersed (K _st ) kaolin obtained from Sigma-Aldrich and Imerys, respectively, were used for flocculation studies. The geometric mean diameter of the K _sm and K _st particles, calculated from the particle size distribution curves (Delsa Nano AT Beckan Coulter), is 0.1-4 µm and 0.6-60 µm, respectively.

Determination of cationic groups in KK. Prior to analysis, cationic starch samples are extracted with methanol in a Soxhlet apparatus for 24 h. Determine the nitrogen content (N,%) in the sample by the Kjeldahl method and calculate the degree of substitution (PL) of the N- (2-hydroxy) propyl-3-trimethylammonium groups in the modified starch by the formula:

\ 62-N where: N,% is the nitrogen content of the sample, 162 is the starch content

J 400 -151.5 · N 'mass of anhydroglucoside residue (AGL)

Determination of N- (2-hydroxy) propyl-3-trimethylammonium groups available in polyanions in the flocculant (P). The amount of cationic groups available to polyanions in cationic starch is determined by titration of their aqueous dispersions by polyelectrolyte dextran sulfate (DeSu). The concentration of DeSu solution is determined by polyelectrolyte titration with a known concentration of polydialyldimethylammonium chloride solution. For analysis, take a quantity of cationic starch solution, add 1 ml of 0,1 N HCl and 1 ml of indicator - 0,05% cation blue Z-dye solution and distilled water to a total volume of 50 ml. Titrate with DeSu's solution with vigorous magnetic stirring until the indicator changes from blue to purple. The amount of cationic groups (ADeSu) available for polyanions (geq / g) in cationic starch is given by the formula:

_V-N. where: V is the titrated volume of DeSu used, ml; N - DeSu A-vesu _m ^, concentration, g-eq / ml; m is the quantity of cationic starch in the volume of the solution to be analyzed, g.

The amount of available cationic groups (P) in cationic starch was calculated by dividing the amount of DeSu-linked quaternary ammonium groups by the total quaternary ammonium group calculated from the amount of nitrogen determined by the Kjeldahl method:

100;

^f A ^A

Z1P & S «\ / 1azoto J Here: AoeSu is the amount of DeSu bonded quaternary ammonium groups, g / g; Aazoto is the total quaternary ammonium content determined by the Kjeldahl method, g-eq / g.

Determination of static flocculation efficiency (D _st ) of flocculant. Preparation of kaolin dispersion: An aqueous dispersion of 1 g / l fine dispersion kaolin (Sigma-Aldrich particle size 0.1-4 µm) is prepared by sonication for 15 minutes.

Kaolin dispersion destabilization: The kaolin dispersion destabilization experiment was conducted at room temperature. Into a beaker of 50 ml of kaolin dispersion, mix with a magnetic stirrer at about 70 rpm (IKA 3 speed), add the necessary amount of flocculant and stir for 10 min at 50 rpm (IKA 2 speed). The dispersions are then allowed to settle for 10 minutes in two fractions and the light absorption of the upper dispersion fraction is measured at 500 nm with a UNICAM UV3 UV / Vis spectrophotometer. The residual turbidity (LD) is calculated using the formula:

LD = SH00,% here: Λ500 / · - light absorption after flocculant application, A500 _p - light absorption of the initial model suspension.

The value of d _sl is calculated as the minimum amount of added flocculant in g / m ³ with a minimum residual turbidity (LD).

Determination of dynamic efficiency (Ddin) of flocculation of kaolin dispersions. Add 200 g of distilled water at 20 ° C to 15 g of K _st and stir vigorously with a magnetic stirrer (IKA, speed 3) for 10 minutes. The resulting dispersion is poured into a 250 ml graduated cylinder, made up to volume with a sufficient quantity of flocculant solution and water to give a total volume of 250 ml. The dispersion is mixed with the cationic polyelectrolyte by rotating the cylinder 180 ° for 10 times. Place the cylinder and measure the height of the clear solution layer at certain points in time. During the tests, sedimentation of the flocculated kaolin particles was restricted. The initial sections of the height dependence of the clear solution layer height versus time curves are lines for which the linear equations have been calculated with a confidence level of at least 0.99. The direction coefficients of the linear equations are the dispersion phase sedimentation rates. The dynamic flocculation efficiency (Ddim) was calculated using the formula:

K

D _djn = - 1. where: V and V 'are the dispersed phase sedimentation rates in mm / min with, respectively

V 'with and without flocculant.

The Ddin score is used to evaluate the flocculant at the C ** range of its optimal dose. If Ddin ^ O, the polymer additive does not affect the stability of the dispersion system. When Dd, _n <0, the polymer stabilizes the system as the ability of the Ddi _n > 0 polymer to flocculate increases.

The efficacy data of cationic starch flocculants are shown in Tables 1-3. Shear-dispersed after the reaction of the starch etherification mixture: H2O2: the water dispersion becomes fluid after a few minutes (Table 1), and the availability of KK ionogenic groups increases dramatically (P). Due to these changes in the flocculant state, the static flocculation efficiency value D _st already after 7 min. dispersions increase threefold - up to 73 percent.

table. KKpl = Availability of o, 3i (P) and Static Flocculation Effectiveness (D _st ) of the flocculant after dispersing the ΚΚ: Η ₂ θ2 aqueous mixture (1: 0.01: 98.99 wt.) With Digital UltraTurrax T25 *

Sample No. Dispersion time, min Availability (P),% Dst, g / m ^{2 3} 1 0 21st 8.0 2 5 66 5.0 3 7th 73 2.7 4 9th 79 2.5 5 11th 89 2.4 1 13th 100 2.0 6th 15th 100 1.9

Note: * The rotational speed of the dispersant rotor at 15000 rpm and Table 3 summarizes the influence of the dispersion composition of cationic starch and its flocculant on flocculation efficiency. Optimal flocculation properties are the aqueous dispersion of the post-reaction mixture of etherification and hydrogen peroxide, wherein the H2O2 is in the range of 0.01 to 0.02 by weight. In this case, the cost of CC flocculant in flocculation is low and the sedimentation rate of the flocculants formed is high. From the data presented in Table 3, it follows that when flocculants are made from N- (2-hydroxy) propyl-3-trimethylammonium starch chloride with 0.28 <PL <0.47 and the target dispersion is dispersed by shear so that N- (2-hydroxy) propyl The availability (P) of the -3-trimethylammonium groups is not less than 73 percent, and the resulting products exhibit greater flocculation activity at lower doses than the prototype dispersed in autoclaved mode to P = 100% (Table 3, prototype) or undispersed by shear. (Table 3, Nos. 12, 13, 15, 16) Flocculants from cationic starch.

table. Dynamic Flocculation Effect of Foculant After Etherification Mixture After Reaction: H ₂ O ₂ : H ₂ O Dispersion 1: 0.01: 98.99 (wt) Dispersion with Digital UltraTurrax T25 *

Sample No. H ₂ O ₂ content Ddin C **, mg / g kaolin 11th 0 37.3 5.5-8.4 7th 0.5 37.8 5.4-7.0 1 1 39.5 5.0-6.6 8th 2 34.0 5.0-7.1 9th 3 25.2 4.8-8.7 10th 4 23.7 5.0-8.1

Note: * Dispersion time of 13 minutes at a rotor speed of 15000 rpm; The optimal dose C ** range is given when Ddin deviates from the maximum value by 10%. Effect of KKpl on Static (D _st ), Dynamic (Ddin) Flocculation Effect of Non-Dispersed and Dispersed Shear Focusing Dispersion

Sample No. KKp _L Do not disperse Disperse * Dst, g / m ³ Ddin C **, g / kg kaolin D _s t, g / m ³ Ddin C **, g / kg kaolin 12th 0.21 3.1 37.8 13.4-20 2.3 36.2 5.4-7.6 13th 0.28 - 27.1 11.1 - 14.4 - 40.7 5.1-5.9 1 0.31 4.0 20.1 7.4-10.4 1.9 39.5 5.0-6.6 14, Prototype 0.32 - 39 15-20 - 12th 6.0-9.2 15th 0.47 4.1 18.3 14-19.2 1.7 40.5 6.4-9.6 16th 0.62 5.8 25.1 7.0-9.8 1.4 33.4 4.6-6.2

Note: * Post-reaction cationization mixture: H ₂ O ₂ : H ₂ O dispersion (1: 0.01: 98.99) dispersed with Digital Ultra-Turrax T25 at 15,000 rpm, 13 min; The optimal dose range C ** is given when Ddin deviates from the maximum value by 10%

The invention is illustrated by the following examples.

N- (2-hydroxy) propyl-3-trimethylammonium starch chloride was obtained by etherification of potato starch (SP Stumbras AB, Antanavas factory, Lithuania) in 70% glycidyltrimethylammonium chloride (GTAC) solution (Fluka, Germany) in alkaline medium. The etherification mixture is prepared by mixing NaOH and glycidyltrimethylammonium chloride (GTAC) solutions and adding starch to such a mixture and mixing the components thoroughly. The molar ratio of reactants in the mixture is AGL: GTAC: NaOH: H ₂ O = 1: 0.315: 0.04: 3.15. Here, 0.315 is the number of moles of GTAC added to the reaction mixture. The reaction proceeds under heterogeneous conditions at 45 ° C for 24 h. The degree of substitution of KK obtained was 0.31 (KK _PL = o, 3i), P = 21%. The flocculation efficiency of the undispersed shear product is D _st = 8 g / m ³ and D dj _n = 20 l at the optimum flocculant dose of C 7.4-10.4 g / kg kaolin (Tables 1-3).

In the preparation of a cationic starch flocculant, the dispersion of the etherification mixture after reaction, the hydrogen peroxide / water dispersion (1: 0.01: 98.99 wt.), Is shear-dispersed at room temperature to form a 1% solution of opalescent flocculant in a Digital Ultra-Turrax T25 dispersant 15000 rpm. at a speed of 13 minutes. The N (2-hydroxy) propyl-3-trimethylammonium groups of cationic starch have a 100% availability (P) after dispersion. D _st = 1,9 g / m ³ , Ddin = 35,9 for an optimal flocculant dose of C 5,0-6,6 g / kg kaolin (Table 3).

example.

The cationic starch flocculant is prepared as in the first example, except that the dispersion of the etherification mixture after reaction, hydrogen peroxide and water (1: 0.01: 98.99 wt.) At room temperature is shear-dispersed to form a 1% solution of opalescent flocculant Digital Ultra-Turrax T25. dispergatorium at 15,000 rpm for 5 minutes. The N-(2-hydroxy) propyl-3-trimethylammonium groups in the cationic starch have an availability (P) of 66% after dispersion. D _st = 5.0 g / m ³ (Table 1).

example.

The cationic starch flocculant is prepared as in the first example, except that the dispersion of the etherification mixture after reaction, hydrogen peroxide and water (1: 0.01: 98.99 wt.) At room temperature is shear-dispersed to form a 1% solution of opalescent flocculant Digital Ultra-Turrax T25. dispergatorium at 15000 rpm for 7 minutes. The N (2-hydroxy) propyl-3-trimethylammonium groups of the cationic starch have an availability (P) of 73% after dispersion, D _st = 2.7 g / m ³ (Table 1).

example.

The cationic starch flocculant is prepared as in the first example, except that the dispersion of the etherification mixture after reaction, hydrogen peroxide and water (1: 0.01: 98.99 wt.) At room temperature is shear-dispersed to form a 1% solution of opalescent flocculant Digital Ultra-Turrax T25. dispergatorium at 15000 rpm for 9 minutes. The N (2-hydroxy) propyl-3-trimethylammonium groups (C) availability of the cationic starch after dispersion is 79%. D _st = 2.5 g / m ³ (Table 1).

example.

The cationic starch flocculant is prepared as in the first example, except that the dispersion of the etherification mixture after reaction, hydrogen peroxide and water (1: 0.01: 98.99 wt.) At room temperature is shear-dispersed to form a 1% solution of opalescent flocculant Digital Ultra-Turrax T25. dispergatorium at 15,000 rpm for 11 minutes. The N (2-hydroxy) propyl-3-trimethylammonium groups (C) availability of the cationic starch after dispersion is 89%. D _st = 2.4 g / m ³ (Table 1).

example.

The cationic starch flocculant is prepared as in the first example, except that the dispersion of the etherification mixture after reaction, hydrogen peroxide and water (1: 0.01: 98.99 wt.) At room temperature is shear-dispersed to form a 1% solution of opalescent flocculant Digital Ultra-Turrax T25. dispergatorium at 15,000 rpm for 15 minutes. The N (2-hydroxy) propyl-3-trimethylammonium groups of cationic starch have a 100% availability (P) after dispersion. D _st = 1.9 g / m ³ (Table 1).

example.

The cationic starch flocculant is prepared as in the first example, except that it is dispersed by shear in a 1: 0.005: 98.995 w / w dispersion of the reaction mixture, hydrogen peroxide and water. Flocculation Effect Ddj _n = 37.8 at an optimal flocculant dose of C 5.4-7.0 g / kg kaolin (Table 2).

example.

The cationic starch flocculant is prepared as in the first example, except that the dispersion of the shear etherification mixture after reaction, hydrogen peroxide and water in a ratio of 1: 0.02: 98.98 (parts by weight) Ddi _n = 34.0 at the optimum dose of flocculant C 5, 0–7.1 g / kg kaolin (Table 2).

example.

The cationic starch flocculant is prepared as in the first example, except that the dispersion of the shear etherification mixture after reaction, hydrogen peroxide and water in a ratio of 1: 0.03: 98.97 w / w D _d i _n = 25.2 at the optimum dose of flocculant C 4.8–8.7 g / kg kaolin (Table 2).

example.

The cationic starch flocculant is prepared as in the first example, except that the dispersion is a 1: 0.04: 98.96 w / w dispersion of a shear etherification mixture, hydrogen peroxide and water. Product Dd _in = 23.7 at an optimal flocculant dose of C 5.0-8.1 g / kg kaolin (Table 2).

example.

The cationic starch flocculant is prepared as in the first example, except that the dispersion of the shear etherification mixture after reaction and water is 1:99 (parts by weight). Product D _n ⁼ 37.3 at an optimal flocculant dose of C 5.5-8.4 g / kg kaolin (Table 2).

example.

The cationic starch was prepared as in the first example, except that the molar ratio of reactants in the etherification mixture was AGL: GTAC: NaOH: H ₂ O - 1: 0.22: 0.04: 3. The degree of CK conversion obtained was 0.21 (KKpl = o.2i). · d _{L d} = 37.8 the optimum flocculant dose C from 13.4 to 20 g / kg of kaolin (Table 3). Product flocculation efficiency after shear dispersion: D _st =

-J

2.3 g / m; Ddin ~ 36.2 for an optimal flocculant dose of C 5.4-7.6 g / kg kaolin (Table 3).

example.

The cationic starch was prepared as in the first example, except that the molar ratio of reactants in the etherification mixture was AGL: GTAC: NaOH: H ₂ O = 1: 0.3: 0.042: 3.15. The resulting CK substitution degree is 0.28 (CKpl = o, ₂ 8). D _d in ⁼ 27, l at the optimum dose of flocculant C 11.1 - 14.4 g / kg kaolin (Table 3).

The flocculation efficiency of the product after shear dispersion by kaolin was Ddin = 40.7 at an optimal flocculant dose of C 5.1 to 5.9 g / kg kaolin (Table 3). When settling municipal sludge (UAB Kauno vandenys UAB) in a fallow metantank, D _d j _n = 19 at the optimum flocculant dose of C 19-20 g / kg dry sludge. Used SP UAB Kauno vandenys methane tank reagent sludge (2012-05-17) containing 2.2% dry matter.

example (prototype)

Cationic starch obtained by prototype methodology [Šablevičienė D, Klimavičiūtė R., Bendoraitienė J., Žemaitaitis A. Flocculation Properties of High-Substituted Cationic Starches // Colloids and Surfaces A: Physicochemical and Engineering Aspects. ISSN 09277757. 2005, vol. 259, p. 23-30]. KK substitution degree 0.32 (KK _PL = o, 32); D _d in = 39 at the optimum dose of flocculant C 15.0 - 20.0 g / kg kaolin (Table 3).

KK _pl = o, 32 One percent water dispersion dispersed in an autoclave at 126 ° C for one hour. The flocculation efficiency of the product is D _d j _n = 12 at an optimal flocculant dose of C 6.0-9.2 g / kg kaolin (Table 3).

example,

The cationic starch was prepared as in the first example, except that the molar ratio of reactants in the cationization mixture was AGL: GTAC: NaOH: H ₂ O = 1: 0.5: 0.04: 4.5.

The degree of substitution of the resulting KK was 0.47 (KK _PL = 0.47) · _Din = 18.3 at the optimal flocculant dose of C 1419.2 g / kg kaolin (Table 3).

β

Product flocculation efficiency after shear dispersion D _st = 1.7 g / m; Ddin = 40.5 at the optimum dose of flocculant C of 6.4-9.6 g / kg kaolin (Table 3).

example.

The cationic starch was prepared as in the first example, except that the molar ratio of reactants in the cationization mixture was AGL: GTAC: NaOH: H ₂ O = 1: 0.8: 0.04: 7.95. The degree of CK substitution obtained is 0.62 (CKpl = o, 6 ₂ ) · Ddi _n = 25.1 at the optimum flocculant dose C of 7.09mg / kg kaolin (Table 3).

Flocculation efficiency of the product after shear dispersion D _st = 1.4 g / m ³ Ddin ⁼ 33.4 at an optimal flocculant dose of C 4.6 to 62.2 g / kg kaolin (Table 3).

Claims (4)

Definition of the Invention 1. A process for the preparation of a cationic starch flocculant by etherification of starch microgranules with glycidyltrimethylammonium chloride and dispersing the resulting N- (2-hydroxy) propyl-3-trimethylammonium starch chloride in water, characterized in that the starch etherification mixture is flocculant with high availability of N- (2-hydroxy) propyl-3-trimethylammonium groups to polyanions. 2. A process for the preparation of a cationic starch flocculant according to claim 1, which comprises dispersing, by shear, a dispersion of the starch etherification mixture after reaction, hydrogen peroxide and water in a ratio of 1: 0.01-0.02: 98.99-98.98 (w / w). components). 3. The cationic starch flocculant obtained by the process of claim 1, wherein the shear-dispersed cationic starch has an N-(2-hydroxy) propyl-3-trimethylammonium group availability of at least 73 percent. 4. The cationic starch flocculant according to claim 3, characterized in that the degree of substitution of the cationic starch in the dispersible shear is from 0.28 to 0.47.