RU2350635C2 - Polyacrylamide flocculant - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: there is disclosed flocculant containing polyacrylamide, modifying agent and water. Modifying agent is carbamide. Component ratio is as follows, wt %: polyacrylamide 0.5-0.7; carbamide 0.15-0.3; water - the rest.

EFFECT: carbamide as modifying agent ensured higher flocculant efficiency.

1 cl, 1 ex, 1 tbl

Description

The invention relates to the production of effective polyacrylamide-based flocculants that can be used for flocculation of coal suspensions and purification of natural and wastewater.

It is known to use a polyacrylamide-based flocculant treated with surface-active substances (SAS), which are hydroxyphobic polyhydric alcohol hydroxyalkylation products. The amount of polymer in a water-dispersible mixture is 12-15 wt.%, Surfactant 88-85 wt.% [1].

However, the addition of these substances reduces the viscosity of the solutions of polyacrylamide, aggravates the mechanical degradation of polyacrylamide. In addition, quite large quantities of expensive and scarce surfactants are used.

Closest to the proposed technical essence is a polyacrylamide-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 [2].

However, this mixture must be dispersed in a solution of a grafted copolymer of polyacrylamide with carboxymethyl cellulose, the interaction takes place at a fairly high temperature of 60-80 ° C and a relatively low efficiency of the flocculant is achieved.

The aim of the invention is to improve the flocculating ability of the flocculant.

This goal is achieved in that the composition based on polyacrylamide, including water and a modifying agent, contains urea in the following ratio of components, wt.%:

Polyacrylamide 0.5-0.7 Urea 0.15-0.3 Water rest

A flocculant was prepared as follows: initially an aqueous solution of polyacrylamide was prepared (molecular weight 30 million, hydrolysis degree 70%, pH range 5-11), which swelled for 1 day at room temperature. Then, with stirring, urea (aminoformic acid amide, urea) was introduced into the polyacrylamide solution (Example 1).

Conducted flocculation of a coal suspension, which contains 100 g / l of solid substance. For separation, a suspension was taken with a content of 100 g / l of solid.

Example 1

A polyacrylamide-based composition was added, including water and a urea modifying agent, in the following ratio of components, wt.%:

Polyacrylamide 0.5 Modifying agent 0.25 Water 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. The results are presented in the table.

Indicators Example 1 prototype Deposition Rate, m / s 0.0250 0.0101 The degree of clarification,% 98 95 The residual solids content in the discharge, mg / l 5 10

As can be seen from the above example, the deposition rate of the coal suspension with a polyacrylamide-based flocculant described in the example is 2.5 times higher than when using the known flocculant.

The degree of clarification in this case increases by 3%. The residual solids content in the discharge is reduced by 2.0 times, which allows a better precipitation of the coal suspension and obtain purified wastewater.

The value of the optimal concentration of the modifying agent depends on the physicochemical properties of the polymer and solvent (water), as well as on the nature of the added substances and is determined experimentally in each case. For each pair of polymer-additive solution there is an optimum concentration, below and above which the degree of crosslinking decreases and the efficiency of the flocculant decreases. This fact is explained by the degree of coagulation of the macromolecule globule, as well as by steric difficulties, when the modifying agent cannot sew individual strands of polymer macromolecules into blocks due to hydrogen bonds.

Information sources

1. US patent No. 363405, CL. 260-33.4, published. 1972.

2. Copyright certificate of the USSR No. 1595850, cl. C08F 220/56, C02F 1/56, published. 1990, bull. No. 36 (prototype).

Claims (1)

A flocculant comprising polyacrylamide, a modifying agent and water, characterized in that, in order to increase the effectiveness of the flocculant, urea is used as a modifying agent in the following ratio of components, wt.%:
Polyacrylamide 0.5-0.7 Urea 0.15-0.3 Water Rest