RU2648437C1 - Modified flocculant on the basis of polyacrylamide - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a process for the production of modified polyacrylamide based (PAA) based flocculants that are successfully used for the flocculation of suspensions in various industries: chemical, coke chemical, pulp and paper, petrochemical and mining, in municipal services and water supply, etc., due to their low cost, low toxicity, high enough efficiency, in many flocculation processes.

EFFECT: method for the preparation of modified polyacrylamide based flocculants is described in which an aqueous solution of polyacrylamide is prepared with the addition of a mixture of propylegolic and urea modifiers.

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Description

The invention relates to a method for producing modified polyacrylamide (PAA) flocculants, which are successfully used for flocculation of suspensions in various industries: chemical, coke, pulp and paper, petrochemical and mining, in public utilities and water supply, etc., due to their low cost, low toxicity, high enough efficiency, in many flocculation processes [2].

A known method for producing PAA-based flocculant, when the reaction product of epichlorohydrin and a mixture of salts of higher fatty acids C ₁₆ -C ₂₀ are used as a modifying agent [5].

The disadvantage of this technical solution is that this mixture must be dispersed in a solution of a graft copolymer of PAA with carboxymethyl cellulose, and the interaction between them occurs at a fairly high temperature (60-80 ° C). This achieves a relatively small increase in the efficiency of the flocculant.

A known method of producing modified flocculant samples by a series of multicomponent mixtures of organic oxygen-containing substances containing propylene glycol, ethyl cellosolve, propylene chlorohydrin [6].

Despite the increased sedimentation ability of the obtained modified flocculants when using the selected modifiers, the disadvantage of this technical solution is the lack of components of the proposed mixtures of modifiers, because their production material resource is low. For this reason, it is impossible to recommend the proposed modified flocculant for mass use in industry.

Closest to the claimed technical solution is the description of the flocculant, including polyacrylamide, a modifying agent and water, in which urea is used as a modifying agent in the following ratio of components, weight. %: polyacrylamide 0.5-0.7; urea 0.15-0.3; water - the rest (prototype) [8].

With a clear advantage of the availability of the proposed modifier (basic nitrogen fertilizer), the disadvantage of this technical solution is the low flocculating ability of the obtained modified PAA solution.

The problem to which the invention is directed is to obtain a modified flocculant having a higher flocculating ability due to several crosslinking agents having different mechanisms for connecting the macromolecular chains of the polymer product (PAA) used.

This problem is solved by modifying the initial PAA, which is dissolved by the necessary technical auxiliary materials: 1) propylene glycol (PG) CH ₃ —CH (OH) —CH ₂ OH; containing two hydroxyl groups with mobile hydrogen atoms; 2) urea (NH ₂ ) ₂ CO containing two amino groups having reactive lone electron pairs at the nitrogen atoms that are able to enter into chemical interactions with the functional groups of PAA macromolecules, while the necessary conditions arise for the modification (crosslinking) of individual macromolecules and the formation PAA structures with increased molecular weight. The choice of such modifiers is not accidental, because they lead to acid-base interactions with the carboxyl and amine groups of PAA with the simultaneous organization of a network of hydrogen bonds due to the presence of PG.

The proposed method for producing modified PAA-based flocculants from its commodity forms necessary for increasing the molecular weight of the flocculant includes a number of necessary technological stages:

1) mixing the selected modifiers with water until they are completely dissolved;

2) adding to the resulting aqueous solution, according to the technological regulations, certain portions of the initial PAA commodity and mixing the resulting mixture until the PAA is completely dissolved and undergoing the modification process;

3) additional exposure of the resulting solution for 60 minutes, leading to the maturation of the solution.

PAA aqueous solutions have a high viscosity, which increases with increasing polymer molecular weight [4]. The higher the molecular weight of the flocculant, the higher its efficiency in the precipitation of the solid phase in suspensions [1]. The industrial method for producing high molecular weight PAA has its technological limitations: it is impossible to obtain macromolecules with an extremely high molecular weight (MM) due to the destruction of hydrocarbon chains [3]. One of the known methods for increasing the molecular weight of PAA is the process of its modification (crosslinking of macrochains) through the use of various modifiers [7]. However, obtaining samples of new highly effective flocculants is limited by the presence of effective modifiers. Their search is currently ongoing.

Example 1 (source PAA). A 0.5% PAA aqueous solution with a volume of 100 ml was prepared from a Magnaflock-345 flocculant powder of the British company Ciba using an exact weighed sample and the sedimentation rate of the model clay suspension and its clarification degree were determined.

Example 2 (prototype). An aqueous PAA solution of 0.5% was prepared from the powder. A PAA-based composition was added, including water and a urea modifying agent, in the following ratio of components, weight. %: polyacrylamide 0.5-0.7; urea 0.15-0.3; water is the rest.

2 ml of a 0.15% flocculant solution was added and the suspension was stirred six times overturning the cylinders.

The deposition rate of the flocculated suspension and the degree of its clarification were determined.

Example 3 (by the proposed method). A 0.5% aqueous PAA solution of the Magnaflock-345 brand of the British company Ciba was prepared with the addition of a mixture of GHG modifiers and urea. The ratio of components,%: flocculant 0.5; PG 0.1; urea 0.05; water is the rest.

0.5 ml of the modified flocculant solution (0.1%) was added to the model clay suspension and the solution was stirred three times in the cylinder.

The sedimentation rate of the model clay suspension, the degree of clarification, and the residual solids content in the discharge were determined.

The results of the tests are presented in the table.

From the experimental data it follows that the deposition rate of the model clay suspension with modified PAA is 2 times higher than in the prototype. The degree of clarification of the solution increases by 1%, and the residual solids content in the discharge decreases by 1%, thereby indicating that the use of modified PAA in the cleaning process gives an undoubted positive effect both to accelerate the flocculation process and to improve the quality of wastewater clarification.

LITERATURE

1. Weizer, Yu.I. High-molecular flocculants in the processes of purification of natural and waste waters / Yu.I. Weizer, D.M. Mintz - M.: Stroyizdat, 1984. - 200 p.

2. 3polsky, A.K. Coagulants and flocculants in water purification processes. Properties Receiving. Application / A.K. Zapolsky, A.A. Ram. - L .: Chemistry, 1987 .-- 167 p.

3. Lipatov, Yu.S. Colloid chemistry of polymers / Yu.S. Lipatov. - Kiev: Science. Dumka, 1984.- 344 p.

4. Softeners, V.A. Polyacrylamide Flocculants / V.A. Myashenkov, A.A. Ram. - Kazan: Publishing house technol. University, 1998 .-- 288 p.

5. Copyright certificate of the USSR No. 1595850, cl. C08F 220/56, c02F 1/56, publ. 1990, bull. Number 36.

6. Pat. RU No. 2330814 C2, MKL ³ C02F 1/56, C08L 33/26 Polyacrylamide-based flocculant / Shevchenko T.V., Ulrich E.V., Yakovchenko M.A., Amelenko V.P., Chuikov A.S. publ. 08/10/2008, Bull. No. 1 mixture of PG EC; PG UGS; PG EC UGS

7. Shevchenko, T.V. Applied Colloid Chemistry. Flocculants and flocculation: monograph / T.V. Shevchenko. KemTIPP. - Kemerovo, 2004 .-- 146 p.

8. Patent RU No. 2350635 C2, MKL ³ C08L 33/26, C08J 3/205, C02F 1/56, B01D 21/01, C08F 20/56, Polyacrylamide-based flocculant / Shevchenko T.V., Ulrich E.V. ., Yakovchenko M.A. publ. 03/27/2009, bull. No. 9 (prototype).

Claims (1)

A method for producing modified polyacrylamide-based flocculants, characterized in that an aqueous solution of polyacrylamide is prepared with the addition of a mixture of modifiers of propylene glycol and urea.