| The ion exchange membrane is widely used for its unique permselectivity.One of the new applications is to obtain high purity electrodeposited metal by using ion exchange membrane to electrolyse metal hydrochloride.This is the ion-film metal electrod eposition process with excellent performance.Because the selective transmission rate of the commodity ion exchange membrane is generally not high,the existing commodity ion exchange membrane is not able to block the occurrence of chloride ions through the membrane completely and the oxidation reaction occurs because of the leakage of chloride ions,producing chlorine gas at the anode and causing serious impact.Therefore,it is necessary to improve the selective permeability of the cation exchange membrane to reduce the leakage rate of chloride ions,which is an urgent problem to besolved in the process of large-scale popularization.In this study,the cation exchange membrane is used as the matrix.In the case of doping with hydrochloric acid,the pyrrole in the cation exchange membrane surface has chemical oxidation then the pyrrole polymerizes and become polypyrrole to modifiy the surface property of the membrane.The four important performance parameters of chloride are ion leakage rate,membrane surface resistance,water content and exchange capacity.Based on these indicators,the effects of polymerization temperature,polymerization time,oxidant type,molar ratio of oxidant,concentration of dopant to pyrrole monomer on the ion exchange membrane have been studied.The experimental datas show that the above five conditions have different effects on the performance parameters of the modified ion exchange membrane.And the parameters of the modified ion exchange membrane can be changed by adjusting the reaction conditions.The optimum conditions of modification are investigated by orthogonality experiments,selecting polymerization temperature,polymerization time,concentration of oxidant(monomer concentration unchanged),concentration of dopant as factors and using the chloride ion leakage rate as the main indicator.The results show that:(1)The order of the above four factors on the chloride ion leakage rate of the modified ion exchange membrane is the concentration of oxidant,the polymerization temperature,the concentration of dopant and the polymerization time.(2)The optimum modified conditions for the combination are that polymerization temperature is 33 ?,the time is 4.75 hours,the conc entration of oxidant is 0.16mol/L and the concentration of dopant is 0.085mol/L.Under these conditions,(1)The surface of the modified ion exchange membrane was black,smooth,flat and uniform thickness,chloride ion leakage rate accounted for only 22.22% of the modified,was only for 2.09%.(2)After the modification,the hydrophilicity,mechanical properties,acid resistance,corrosion resistance,energy consumption and selectivity of the membrane were obviously improved compared with the original membrane.(3)The results of infrared spectroscopy showed that the effect of polypyrrole combined with membrane was well.(4)After the electrolysis of the membrane itself without significant changes in character,and continuous electrolysis 204 h later,there is still a certain ability to intercept chloride ions,electrolysis life than the original film to be extended.(5)When applying this modification method to other types of cation exchange membranes,the membrane properties are also improved to varying degrees.And the the electrolytic life of the cation exchange membrane is extend.This indicates that the polypyrrole impregnation modified cation exchange membrane is practicable and can effectively solve the problem of chlorine gas generation in the ion plating process.At the same time,this modification method can provide reference for improving the performance of ion exchange membrane of China's membrane industry,and further expand the innovative applications of ion exchange membrane. |
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