SU1416496A1 - Method of producing cation exchange membrane - Google Patents

Abstract

The invention relates to the production of cation-exchange membranes and can be used in water treatment for electrodial from multicomponent solutions. The invention makes it possible to increase the reproducibility of specific selectivity to single charge cations from 3.8-10 to 22.4-50.0 and electrical resistance to 4.8 Ω x X cm, as well as to simplify the technology by reducing the stages of the process. The effect is achieved by the fact that the sulfo-chlorinated film is made from an interpolymer of polyethylene and structured. polystyrene is treated with an aprotic solvent and then is amidated with N, N-dialkyl-substituted diamine with the number of methylene groups 2-4. I zp f-ly, 2 tab. with (L

Description

65

four

:about

Od

It is used to manufacture articles from molded organic, high molecular weight materials, in particular, to fabricate semipermeable cationite membranes that have selective permeability to certain ions, and can be used in water treatment for electrodialysis of multicomponent solutions, including collector-drainage water (KDV). ) containing predominantly sodium chloride.

The aim of the invention is to increase the reproducibility of specific selectivity to single charge cations and electrical resistance, as well as to simplify the process.

Example 1. A chlorosulfonated film based on polyethylene and structured polystyrene is treated at room temperature with dried dichloroethane until there is no trace of Cl in the eluate (sample on AgNC3)

The washed chlorosulfonated film is amidated with a 0.3 M solution of dimethylpropylene lamine (DMPDA) in DCE (Table 1, amine 2) for 5 min at 20 ° C.

The amidated film is immersed for 6 hours at AO C in 10% sodium hydroxide solution to launder unreacted sulfochloride groups. After saponification, the film is washed of alkali with distilled water, then with sodium chloride and stored in a 0.5 M solution of sodium chloride. The resulting membrane has the following properties:

p 0.17; p 2.8 ohm cm

/ S

32.5.

Examples 2-28. Similarly, membrane preparation experiments are carried out using other amines, solvents and conditions.

These experiments are presented in Table. one.

The selective permeability of the membranes to single charge to the ions is estimated by the value of specific selectivity P:

/ 7 J. and 2 p OUTPUT) ON THE CURRENT ONE AND

bicarbonate cations. The membrane is selectively permeable to 5 to single charge ions at P 1 and to double charge ions to P. In this case, the closer Pj tends to O, the more selectively permeable the membrane is to single-charge cations, in 10 particular K and K. The reproducibility of 1 / Sr was estimated by the formula

1 / Sr C / S (2) 15 where S is the standard deviation

LShS -. WITH)

n - 1

(3)

where C is the arithmetic mean value

a definable quantity; C - measured value. From formula (2) it is assumed that

the numerical value of reproducibility increases as the standard deviation S decreases. In the case of a standard deviation of zero, l / S, - oo. The higher the standard deviation, i.e.

the greater the variation in the values in the sample of a definable quantity, the 1/5 is smaller.

The need for thorough washing of the film from traces of chlorosulfonic acid (HSC) is due to the fact that

due to the good solubility of HSC in the proposed aprotic solvents, there is an almost complete mixing of the free HSC and the sulfochlorination reaction products from the membrane

without any changes in the structure. This makes it possible to obtain a membrane with high electrochemical characteristics and provides a high reproducibility of the process. The absence of

mobile hydrogen atoms in the structure of the solvent used in the amidation, avoids the side processes leading to inactivation of the amine and saponification of the CX groups.

In tab. 2 shows the comparative data on the properties of the known and proposed membranes.

i 4i

(one)

 II

where Cf and Cj. —concentrations of one- and two-charge cations in the initial solution;

Claims (2)

1. A method for producing a cation-exchange membrane by amidation of a sulfonated film from an interpolymer of polyethylene and structured polystyrene and the subsequent sulphication of sulfonyl chloride groups with an alkali solution, in order to increase the reproducibility of specific selectivity to single-charge cations, and also simplify the process, before amidation, the film is subjected to treatment with an aprotic solvent selected from the group including dichloroethane, carbon tetrachloride, ethyl acetate, dioxane, and imetilsulfoksid, and amidation is carried out in said solvent an aliphatic diamine of the general formula  - (CHj), - N, R) where,,,, n 2-4. 2. The method according to p. 1, the difference is U. and in that the amidation is carried out with a 0.3-0.9 M solution of diamine for 3-10 minutes. Table Note. DMPDA - S, K-dimethylpropylene diamine; DMEDA - K, K-dimethyl-ethylenediamine; DEPDA-M, L-diethylpropylene diamine; DPPDA - K, L-dipropylpropylenediamine; MEPDA - H, K-methylethylpropylene diamine; DMBDA - N, N-dimethylbutylenediamine; DMGMDA - K, L-dimethylhexamethylenediamine; BPPDA - M, N-butylpropylpropylenediamine; , CE - dichloroethane; DMSO - dimethyl sulfoxide; EAC - ethyl acetate. " I Table 2 2, 8 2.3 3.0 0.16-0.30 Continued tabl, 1 2, and 2.3 2.8- /., 8 0 16-0,22 Membrane properties The known method Initial Modified Reproducibility 1 / s; i / s Compiled by V. Mcrtychan. Editor T. Lazorenko Tehred A. Kravchuk Proofreader S. Shekmar Order 4031/22 Circulation 434 VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Ipt-i. io. iH gchg. b; i (i, n, The proposed method Initial Modified 4.2-16.0 3.8-10.2 30.0-64.0 22.4-50.0 Subscription