SU1077903A1 - Solution for forming ultrafiltering membranes - Google Patents

Abstract

SOLUTION FOR FORMING ULTRAFILTRATION MEMBRANES, contents cellulose, dimethylformamide, nitrogen tetroxide and modifying additive, characterized in that, in order to increase the retention capacity of membranes, the solution contains ethyl acetate as the modifying additive in the following ratio of components, May.%: Cellulose 8 Nitrogen tetraoxide 12-20 Dimethylformamide 37.7-75.6 Ethyl ester of acetic acid7.4-37.8

Description

The invention relates to the production of semipermeable membranes / in particular to the production of cellulosic hollow fibers and films used in ultrafiltration processes. A known solution for forming hydrated cellulose hollow fibers or leaf membranes, consisting of cellulose xanogenate, sodium hydroxide and water and containing a modifying additive, styrene sulfonate on ri Cl. A significant disadvantage of this solution is that the membranes obtained from it have low productivity and retarding capacity, which limits their use in membrane technology. The closest to the proposed is a solution, which includes cyjulum, dimethylformamide, nitrogen tetroxide and water as a modifying additive 2. The use of this solution allows to obtain high-performance membranes with high production of Tej bHOCTbic. However, in many technological processes using membranes, it is necessary to ensure the retention of dissolved substances with a molecular mass of 1020 thousand kg / kmol, which is practically impracticable using existing cellulosic membranes. The aim of the invention is to increase the delayed ability of the membranes. The aim is to achieve that the solution for forming ultrafiltration membranes containing cellulose, dimethylformamide, nitrogen tetroxide and a modifying additive, contains ethyl acetate as the modifier in the following ratio of components, wt. .%: Cellulose4-8 Nitrogen tetraoxide 12-20 Dimethylformamide 37.7-75.6 Ethyl ester of acetic acid 7.4-37.8 Addition of acetic acid ethyl ester to the solution of cellulose indicated amounts due to the fact that when the content of ethyl acetate in the solution is less than 7.4%, a noticeable increase in the selective properties of the membranes obtained from it is not observed, and when introduced more than 37.8% there is no further increase in the retention capacity of the membranes. Example. 4-8 wt.% Pulverized cellulose is poured with a pre-prepared mixture of the composition, wt.%: Dimethylformamide (DKFA) 37,7-75,6 Nitrogen tetroxide (K204I12-20 Ethyl acetate (EDG 7.4-37.8 in the amount of 92-96 wt.% and stirred to obtain a clear viscous solution. The resulting solution after filtration and deaeration is applied with a thin layer (200-300 µm) on a polished surface, kept for 3-5 minutes in air with a relative humidity of 60-80% and then immersed in water. The resulting membrane is washed in water to a constant pH value. and and the retarding capacity R of the membranes obtained is carried out on a FM-02-200 membrane filter at a pressure of 1.0 atm and a temperature. A 0.3% aqueous solution of polyethylene glycols with a molecular weight of 6000 and 40000 kg / The composition of the molding solutions and the characteristics of the membranes obtained from them are given in Table 1. The effect of the modifying additive on the properties of the resulting membranes is given in Table. 2. Table 1

75.6

four

12.0

4 84.0 12.0 67, b 18.9

7

7 74.1 18.9

11245,496,7

12710.2. 61.4

37,683,9100

55,238,992,2

The blank experiments are given for comparison.

The blank tests are given for comparison.

As can be seen from the data given in table. 1 and 2, the introduction of ethyl acetate ester into the cellulosic solution makes it possible to obtain membranes on its basis that effectively inhibit high molecular weight substances of molecular weight.

Continued table. one

table 2

6000 kg / kmol. This allows significant. But to expand the field of application of cellulose ultrafiltration membranes in various industries related to the separation and purification of: high molecular compounds, biologically active substances and colloids.

Claims (1)

A SOLUTION FOR FORMING ULTRAFILTRATION MEMBRANES, cellulose, dimethylformamide, nitrogen tetroxide and a modifying additive, characterized in that, in order to increase the retention capacity of the membranes, the solution contains ethyl acetate in the following ratio, May.%: Cellulose 4-8 Nitrogen tetraoxide 12-20 Dimethylformamide 37.7-75.6 Acetic acid ethyl ester 7.4-37.8>