RU2275385C1 - High-molecular weight (meth)acrylic anionic flocculant production process - Google Patents

Abstract

FIELD: polymer production.

SUBSTANCE: invention relates to a method for production of high-molecular weight water-soluble polymers used as flocculant at enterprises of water conditioning, petroleum processing, petrochemistry, iron and nonferrous metallurgy, paper-and-pulp, varnish-and-paint, chemical, and other industries. In particular, invention provides a method for production of high-molecular weight (meth)acrylic anionic flocculant via copolymerization of water-soluble anionic ethylenically unsaturated monomer with nonionic ethylenically unsaturated monomer, the former being salt of (meth)acrylic acids and the latter (meth)acrylic acid amide and ester at salt/amide/ester ratio 100:10:(1-6) or 100:(1-6):10. Proposed method leads to production of high-molecular weight (meth)acrylic anionic flocculant in the form of powder with nearly 100% content of principal substance, which is well dissolved in water.

EFFECT: enhanced efficiency in treatment of various disperse systems (industrial effluents).

3 cl, 4 tbl, 4 ex

Description

The present invention relates to a method for producing high molecular weight water-soluble polymers used as flocculants, and can be used in water treatment, oil refining and petrochemical industries, ferrous and non-ferrous metallurgy, pulp and paper, paint and varnish, chemical and other industries.

Currently, the most common are polyacrylamide flocculants (PAA). However, they are produced in most cases in the form of a gel with a polymer content of 7-11%. So in Russia PAA is produced with a pier. m. - 4 · 10 ⁵ and the degree of hydrolysis - 5% in the form of an 8% gel.

The low polymer content of these products makes it unprofitable to transport and store them, since it is necessary to transport mainly water. In addition, the shelf life of polyacrylamide gel is only 6 months, and the stability of aqueous solutions is several days.

Abroad (USA, Japan, Germany, France, Italy, etc.) a large assortment of polyacrylamide flocculants is produced in powder, granular and gel form under various commercial names: Magnoflock, Praestol, Superflock, Fennopol and others ("Coagulants and flocculants in processes water purification. Properties. Obtaining. Application. "Zapolsky AK, Baran AA L .: Chemistry, 1987).

Closest to the claimed technical essence and the achieved result, selected as a prototype is a method of obtaining a high molecular weight water-soluble anionic polymer flocculant, protected by RF patent No. 2026867, cl. C 08 F 2/38, C 08 F 20/02, C 08 F 22/02, C 08 F 226/10, C 02 F 1/56, B 01 D 21/01, publ. 20/01/1995.

The method consists in the polymerization of anionic water-soluble monomer with a double bond or its copolymerization with a nonionic monomer with a double bond in the presence of a branching compound, taken in an amount of 4-80 mol.h. per 1 million in terms of the initial content of monomers with double bond. The copolymerization is carried out in the presence of a kinetic chain carrier, taken in an amount that ensures the viscosity of the copolymer in the solution at least 3 MPa when measured in a Brookfield viscometer with an UL adapter at 25 ° C, a polymer concentration of 0.1 wt.% In 1 M NaCl at 60 rpm

Compounds selected from the group consisting of (meth) acrylic acid, sulfoalkyl (meth) acrylic acid, styrene sulfonic acid, unsaturated dicarboxylic acid, sulfoalkyl (meth) acrylamide, salts of these acids are used as anionic water-soluble monomers with a double bond. A non-ionic monomer is a compound selected from the group consisting of (meth) acrylamide, N-alkyl acrylamide, N, N-dialkyl acrylamide, vinyl acetate, alkyl (meth) acrylate, acrylonitrile, N-vinyl methylacetamide, N-vinyl pyrrolidone.

The flocculants obtained in a known manner are poorly soluble in water. The product is a ~ 30% aqueous emulsion, which increases its transportation cost and creates instability of properties during storage.

The objective of the claimed invention is to provide a method for producing a highly effective high molecular weight (meth) acrylic water-soluble anionic flocculant.

The technical result from the use of the invention is to obtain a high molecular weight (meth) acrylic anionic flocculant in the form of a powder (~ 100% of the basic substance) readily soluble in water, highly effective for cleaning various dispersed systems (industrial stocks), as well as to increase the stability of working aqueous solutions of flocculant .

This result is achieved by the fact that in the method for producing a high molecular weight (meth) acrylic anionic flocculant by copolymerization of an anionic water-soluble monomer with a double bond with a nonionic monomer with a double bond, salt, amide and ether of (meth) acrylic acids are used as starting monomers in the ratio salt: amide: ether of (meth) acrylic acids equal to 100: 10: (1-6) or 100: (1-6): 10.

Alkali metal salts are used as the (meth) acrylic acid salt, and methyl or ethyl ether are used as the (meth) acrylic acid ester.

The method is as follows.

Equimolar amounts of (meth) acrylic acid (TU 6-02-59-89) and caustic soda (GOST 2263-71) in demineralized water (TU 6-01-2-22-77) are charged into a reactor equipped with a reflux condenser. An appropriate amount of the sodium salt of (meth) acrylic acid is formed. Then add the amide of (meth) acrylic acids (OST 6-01-226-87) and methyl ester of (meth) acrylic acids (GOST 20370-74), taken in the ratio 10: (1-6) or (1-6): 10 per 100 vol. salt. The solution is heated to 50-60 ° C with stirring and an aqueous solution of initiator (e.g. potassium persulfate) is introduced (TU 38-1032-70-81). The synthesis of the copolymer lasts 50-70 minutes Then the reaction mass is evaporated to a copolymer content of 60-70%, crushed and dried at a temperature of 65-70 ° C to a moisture content of not more than 5%. The processes of evaporation and drying to achieve the required percentage of the actual copolymer can be replaced by other methods of reducing moisture content.

The characteristic of this product is the kinematic viscosity of a 1% aqueous solution. This value is indirectly related to the molecular weight of the copolymer: the higher the kinematic viscosity, the greater the molecular weight of the copolymer. The kinematic viscosity is determined according to GOST 18249. The kinematic viscosity of a 1% copolymer aqueous solution obtained by this method is in the range of 20-250 cSt.

The following examples illustrate the invention.

Example No. 1

In a reactor equipped with a stirrer, 85 g of methacrylic acid are dissolved in 250 ml of demineralized water and 37 g of sodium hydroxide are added. An aqueous solution is formed containing 100 g of methacrylic acid sodium salt. Then, with constant stirring (240 rpm), 6 g of acrylic acid amide and 10 g of methacrylic acid methyl ester are added. Thermostat the reaction mixture at 60 ° C and add 0.1 g of initiator (potassium persulfate). The synthesis is continued with constant stirring for 60 minutes. Then the reaction mixture was evaporated. The resulting copolymer is ground and dried.

Examples 2-4 carried out analogously to example No. 1. The composition of the monomer mixture and the kinematic viscosity of the obtained products are shown in table No. 1.

From table No. 1 it follows that depending on the ratio of the anionic water-soluble monomer with a double bond and the nonionic monomer with a double bond, the molecular weight of the resulting copolymer changes, which affects the kinematic viscosity of a 1% aqueous solution. The monomer ratio was established experimentally. With lower amounts of amide and ether (meth) acrylic acids, a copolymer with a low viscosity (lower molecular weight) is formed, which negatively affects the effectiveness of the flocculant. With large amounts of amide and (meth) acrylic ester, an inhomogeneous copolymer is formed, which is difficult to dissolve in water.

Table 2 shows the comparative results on the cleaning of galvanic drains by the flocculant obtained in Example 3 and the polyacrylamide gel (PAA) flocculant (TU 6-01-1049-92). The concentration of flocculant obtained by the proposed method was 1 mg / DM ³ and the concentration of polyacrylamide - 20 mg / DM ³ . From the data of table No. 2 it follows that the effectiveness of the flocculant obtained by the proposed method is higher than that of PAA at a lower (20 times) concentration in solution.

Analysis for the content of metal ions was carried out in accordance with GOST R 51309-99.

Table 3 shows the comparative cleaning results of the model system — 1% dispersion of kaolin in water by the flocculants obtained according to Examples Nos. 1–4 and the Fennopol A321E flocculant (produced by Kemira Chemicals Oy, Finland).

The efficiency of flocculants was assessed by the following characteristics: kinematic viscosity, clarification rate, time to reach full clarification of the dispersion, the clarification limit of the dispersion, determined by the “Instructions for conducting trial coagulation on water from a surface source of drinking water of the Volga River”. The flocculation rate was calculated from these characteristics.

The concentration of flocculants was equal to:

- "Fennopol A321E" - 0.02 mg / dm ³ ;

- No. 1-4 - 0.01 mg / DM ³ .

From the data of table No. 3 it follows that the efficiency of the obtained copolymer samples is comparable and even exceeds the efficiency of a similar known product - "Fennopol A321E".

The stability of aqueous solutions of flocculant was determined by the change in the kinematic viscosity of a 1% aqueous solution over time (table No. 4).

As can be seen from the above data, the viscosity of the aqueous solution of the flocculant practically does not change for five months.

Thus, the proposed method in comparison with the prototype allows to obtain a highly effective anionic (meth) acrylic water-soluble flocculant in the form of a powder that can be used to clean industrial wastes, as well as drinking and recycled water. The product is obtained in a form convenient for transportation and storage. Aqueous solutions of it are stable over time. The efficiency of cleaning dispersed systems is already apparent at very low concentrations from 0.01 to 1 mg / DM ³ .

Table number 1 Starting monomers, g Example 1 Example 2 Example 3 Example 4 Methacoyl Acid Methyl Ester 10 10 6 one Amide Acrylic Acid 6 one 10 10 Sodium salt of methacrylic acid (methacrylic acid - 85 g, sodium hydroxide - 37 g) one hundred one hundred one hundred one hundred Kinematic viscosity of 1% aqueous solution, cSt 250 152 38 twenty

Table number 2 Metal ions Inlet concentration, mg / l Concentration after precipitation, mg / l Example No. 1 PAA Cu ²⁺ 10.78 1,325 1,6 Fe _commonly 11.13 0,078 0.125 Ni ²⁺ 3.2 Absent 0.06 Zn ²⁺ 0.33 0,085 0,1605 PAA - Polyacrylamide Gel (TU 6-01-1049-92)

Table number 3 Flocculant Kinematic viscosity, cSt The speed of clarification of the dispersion,% / 20 s Time to achieve full clarification, s The clarification limit,% Flocculation rate Phenopol K211E 85,2 68 60 85 21.7 No. 1 250 83 45 92 28.7 Number 2 152 thirty 180 92 9.0 Number 3 38 17 240 83 4.8 Number 4 twenty 6 210 63 1,2

Table number 4 Time, day one thirty 60 90 120 150 Kinematic viscosity of a 1% aqueous solution (example No. 1), cSt. 250 250 250 250 250 250 Kinematic viscosity of a 1% aqueous solution (example No. 3), cSt. 38 38 38 38 38 38

Claims (3)

1. A method of obtaining a high molecular weight (meth) acrylic anionic flocculant by copolymerization of an anionic water-soluble monomer with a double bond with a nonionic monomer with a double bond, characterized in that the salt of (meth) acrylic acids is used as the anionic water-soluble monomer with a double bond, and as a nonionic monomer with a double bond, the amide and ether of (meth) acrylic acids are used with a salt: amide: ether of (meth) acrylic acid ratio of 100: 10: (1-6) or 100: (1-6): 10. 2. A method of producing a high molecular weight (meth) acrylic anionic flocculant according to claim 1, characterized in that alkali metal salts are used as the salt of (meth) acrylic acids. 3. A method of producing a high molecular weight (meth) acrylic anionic flocculant according to claim 1, characterized in that methyl or ethyl ether is used as the (meth) acrylic acid ester.