Preparation Of Anion Exchange Membrane And Study On Desalination Performance Of Electrodialysis

As a key component of electrodialysis technology,anion exchange membranes have problems such as complex preparation process,high energy consumption and low lifespan,which greatly limit the commercial application and the development of electrodialysis in seawater desalination.Therefore,two anion exchange membranes with simple process and excellent performance were developed for electrodialysis desalination in this paper.First,PVDF-PVIm anion-exchange membranes were prepared by in-situ polymerization using PVDF as the membrane support structure,vinylimidazole（VIm）as the functional monomer and dibromohexane as the cross-linking agent.The morphology and structure of the membranes were characterized by SEM,FT-IR and TGA,and the effects of VIm and dibromohexane additions on the membrane properties were also explored.When the VIm content is 42 wt%and the crosslinking agent content is 15 wt%,the PVDF-PVIm membrane has the best comprehensive performance,its IEC is 2.21 mmol g^-1,WU is 41.3%,Rm is 2.37Ω·cm²,and P is 97.85%.In the electrodialysis desalination test,the highest desalination rate was 99.6%,the energy consumption was1.87 k Wh kg^-1,and the concentration ratio was 94.3%.Secondly,in order to improve the service life of ion exchange membrane in high temperature and high alkali environment,brominated polyphenylene ether（BPPO）was used as the main chain structure of the membrane,and the crosslinking agent N,N’-carbonyldiimidazole（CDI）and The hydrophobic monomer octadecyldimethyl tertiary amine（DMODA）prepared PPO-CDI-DMODAs anion exchange membranes.The morphology and structure of the membranes were explored by characterization methods such as SEM,FT-IR and TGA,and the effect of the addition amount of the crosslinking agent CDI on the membrane properties was also explored.When the CDI content was 3%,the PPO-CDI-DMODAs film had the best comprehensive performance,with IEC of 1.85 mmol g^-1,WU of 13.5%,Rm of 2.52Ω·cm²,and P of97.4%.In the electrodialysis desalination test,the desalination rate was98.0%,the energy consumption was 2.38 k Wh kg^-1,and the concentration ratio was 90.2%.The high-temperature and high-alkali test showed that the film performance decreased slightly,of which the IEC decreased by 5.41%and the P decreased by 3.08%.