Method for preparing homogeneous-phase cation-exchange membrane

Abstract

The invention relates to a method for preparing a homogeneous-phase cation-exchange membrane. In the method, a binary blending alloy film of polyethylene and the copolymer elastomer of ethylene and octylene, or the ternary blending alloy film of polyethylene, copolymer elastomer of ethylene and octylene and isobutylene rubber is taken as a basilar membrane. The method comprises the following steps: dipping the basilar membrane into the solution containing styrene, divinyl benzene and peroxide benzoyl; pressurizing an impregnated film and heating and polymerizing to obtain the basilar membrane; and sulfonating the basilar membrane in concentrated sulfuric acid to obtain the cation-exchange membrane. The cation-exchange membrane has the advantages that: the alloy membrane has elasticity and flexibility, greatly enhanced mechanical property and toughness; the impregnated temperature is reduced greatly; and the polyethylene and ethylene solution can be recycled, the prepared cation-exchange membrane has high capacity which can be 2.5 milliequivalent / g dry film, the sheet resistance is about 1cm<2>, and the dichloroethane is not needed for pre-swelling the basilar membrane during the sulfonation.

Description

technical field [0001] The invention relates to a method for manufacturing a cation exchange membrane in membrane separation materials in the field of chemical engineering. Background technique [0002] The cation exchange membrane is one of the key components in the ion exchange membrane electrodialysis device. Ion exchange membrane electrodialysis devices are widely used in desalination of seawater and brackish water to prepare drinking water, desalination and purification of organic compounds, preparation of high-purity water and ultra-pure water for high-pressure boilers in the semiconductor industry, electronics industry and power plants, and industrial wastewater treatment and reuse. [0003] A method for producing a cation exchange membrane by the impregnation method of impregnating a polyethylene film with styrene or divinylbenzene is known. US Patent No. 4,024,043 discloses a method for manufacturing a bipolar membrane based on a polyethylene film. This method use...

AI Technical Summary

Problems solved by technology

The disadvantages of this method are (1) the use of high-density polyethylene film and ultra-high molecular weight polyethylene film as the base film

Due to the high crystallinity of the polyethylene film, the compact structure, and the small range of amorphous regions, styrene and divinylbenzene are not easy to enter the interior of the film. It is necessary to partially destroy the crystalline region of the film at high temperature (70-90°C) to make it Styrene and divinylbenzene enter, but the amount of entry is not much, so the prepared basement film contains the amount of styrene and divinylbenzene (called the impregnation rate, which is defined as the basement film after immersion and polymerization under pressure and heating). The weight of the obtained base film (w 2 ) minus the weight of the original basement membrane (w 1 ) divided by the weight of the original basement membrane (w 1 ) is the impregnation rate, its formula is ×100%) is not high, at most 45%. In this way, the exchange capacity of the cation exchange membrane of the prepared positive layer is not high, and the resistance is relatively large

(2) In this method, the membrane is soaked at 70-90°C, and the initiator benzoyl peroxide will decompose at 80°C, triggering the copolymerization reaction of styrene and divinylbenzene, so it is easy to cause polymerization during the dipping process reaction, or make the solution viscous, the solution should only be used once and discarded

Dichloroethane is toxic and not good for mass production

The resulting cation exchange membrane is inelastic