Preparation And Characterization Of An Anion Exchange Membrane For Concentrated Acids Based On Tertiary Amine Groups

In the field of industrial production,it will produce lots of waste acid.if we dump directly instead of recycling,waste acid will cause serious pollution in environment.The current approach of disposal is to neutralize lime before dumping,it is not only inefficient and expensive,but also results in waste of resources.If we concentration dilute acid to high concentration by electrodialysis technology,it will reduce furthest the consumption of resources,and the whole process is environmental friendly,satisfies the requirements of sustainable development.Ion exchange membrane as a core component of the electrodialysis performance is very important.In order to meet the special requirements of electrodialysis concentration acid technology,excellent mechanical properties and electrochemical properties of the anion exchange membrane are expected,beyond that it is even more important to minimize proton leakage across the membrane under a concentration gradient.This is why common anion exchange membranes are difficult to apply in this technology.Thermoplastic engineering material poly-p-phenylene oxide(PPO)is widely used in the field of anion exchange membranes because of good thermal stability,chemical stability,low cost and simple structure.Click chemistry reaction has excellent performance in polymer synthesis and membrane preparation due to its mild reaction conditions,high synthesis speed and high yield.In order to obtain an anion exchange membrane with lower protonion leakage.In this paper,DEP-x series polymers were synthesized by click chemical method and introduced tertiary amine type anion exchange groups into the PPO main chain.The results of electrodialysis showed that the concentration limitation of hy proton of DEP-30 membrane was 3.02 mol/L,slightly higher than that of ACM membrane.The IEC value,Water Uptaket,Swelling degree,Transport number,Membrane area resistance and electrodialysis performance of the membrane were analyzed and discussed.The main factors affecting the proton leakage of the anion exchange membrane are the types of anion exchange groups and the water uptake of the membranea and swelling degree.The area resistance of DEP-30 was 3.7 ?cm2 which was lower than ACM in spite of similar IEC.In general,the electrodialysis performance of membranes with tertiaxy amine anion exchange groups is more excellent than that of membranes with quaternary ammonium groups;membranes with lower water content and swelling have better electrodialysis performance.Based on the first part of the study,in order to study the influence of hydrophobic alkyl chains and their length on membrane performance,we introduced the alkyl chain with different length into the interior of the anion exchange membrane with tertiary amine by click-chemistry method.The results shown that concentration limiting of C8X35Y5 was 3.025mol/L.The performance of the prepared anion exchange membrane was analyzed and found that the introduction of hydrophobic alkyl chains can effectively reduce the water uptake,and swelling degree of the membranes because the dense structure reducing the proton leakage during electrodialysis process.