BPPO And PVA Based Hybrid Ion Exchange Membranes For Diffusion Dialysis

Ion exchange membrane separation technology is highly efficient,energy-saving, easy to control and can realize separation of materials in anormal temperature without pollution of the environment. This technology hasthe function of separation, enrichment, purification and refining.Therefore,it ispaid much attention by more and more researchers and has been widely appliedin many fields such as water treatment, metallurgy and food industry. For thistechnique, membrane is the core and its function is largely determined by theproperties of the membrane material. Organic-inorganic hybrid ion exchangemembranes can combine the advantages of inorganic and organic membranes,such as flexibility, film-forming performance, strength, hardness,thermodynamic, mechanical and chemical stability. Therefore, they are widelyutilized in the separation process with great application potential.In this paper, several organic-inorganic hybrid ion exchange membranes areprepared by methods such as phase inversion and sol-gel and then characterizedfor application in diffusion dialysis. The main processes and some importantdata are as following:(1) Brominated poly （2,6-dimethyl-1,4-phenylene oxide）（BPPO） is usedto undergo phase inversion,partial hydroxylation, filling of multi-siliconcopolymer （poly（maleic anhydride-γ-methacryloxypropyl trimethoxy silane），poly（MA-co-γ-MPS））, and quaternization to yield hybrid ion exchangemembranes. Results show that the membranes have porous structure and goodresistance to swelling in65oC hot water. When applied for diffusion dialysisprocess to recover HCl from HCl/FeCl2mixture, they show H+dialysiscoefficients（UH） of0.020-0.025m/h and HCl/FeCl2separation factors（S）up to45.5. Therefore, the membranes have good application prospect.(2)With3-chloride propyl triethoxy silane and PVA as raw materials, hybridanion exchange membranes are prepared through sol-gel reaction andquaternization. The hybrid membranes have good thermal stability, mechanicalproperties, high hydrophilicity and good stability in65oC hot water. They areapplied in diffusion dialysis process to recover HCl from HCl/FeCl2mixture.Itturned out that the UHvalues are in the range of0.00937-0.01854m/h and S values are up to46.1.(3)2-ethyl sulfonic acid sodium reacts with γ-aminopropyltriet hoxysilane（A-1100）, then mixed with poly（vinyl alcohol）（PVA） to form the hybridcation exchange membranes through sol-gel reaction. The membranes have goodthermal stability with Td values of250.7-293.6oC, IDT of184.5-220.4oC, goodmechanical properties, with elongation of300%-529%. The ion exchangecapacity is0.62-0.74mmol/g.The membranes are applied for diffusion dialysisprocess to recover NaOH from NaOH/Na2WO4mixture. It turned out that thedialysis coefficients of OH（-UOH）are in the range of0.00949-0.01477m/h andNaOH/Na2WO4separation factors（S）is up to23.6.