Preparation,Characterization And Modification Of Heterogeneous Cation Exchange Membranes

Membrane separation technology is a new and efficient separation technology,which is very suitable for modern industry.It has the characteristics of energy saving,increasing production efficiency,material recycling and environmental friendliness.Ion exchange membrane is an important component in membrane separation technology and has been widely used.Resources recycling,water treatment,fuel cells and desalination.The heterogeneous membrane has the characteristics of simple production process,low pollution in the production process and low price.The performance defects of the existing heterogeneous membranes greatly limit the application range.Therefore,in this paper,silane cross-linked polyethylene is first used as the membrane skeleton,and three different ion exchange resins of 001�7,001�12 and D001 are used to prepare the membrane.Three series of ion exchange membranes were prepared by setting the ratio of ion exchange resin powder to CEM-A,CEM-B and CEM-D.The membrane properties were characterized by ion exchange capacity,water content,migration number,membrane resistance and chloride ion leakage rate.To study the effect of different ion exchange resins on the prepared ion exchange membrane under different ratios.Then,the CEM-A3 film with excellent comprehensive performance was selected,and the polymer blended with PWA/PVA-TEOS was used for the leaching modification.The water bath treatment time of the 1%H₂O₂ solution,the solute mass ratio of the immersion solution,and the immersion solution were investigated.The effect of solution concentration and heat treatment time on the membrane modification effect was analyzed by scanning electron microscopy and Fourier transform infrared spectroscopy.Finally,the CEM-A3 membrane,modified membrane and commercial membrane were treated in a continuous water bath for 240 h in 60�C,5%H₂O₂ solution.The membrane properties were compared before and after oxidative treatment,and the structure of the three membranes difference was analyzed in chemical stability.Ion exchange resins are an important part of heterogeneous cation exchange membranes,and differences in resin types and membrane formulations can cause changes in membrane properties.When the ratio of 001�7 resin is 67%,the overall performance of the prepared membrane is the best;when the ratio of 001�12 resin is 65%,the overall performance of the membrane is the best.When the ratio of 001�7 resin is 67%,the overall performance of the prepared membrane is the best;when the 001�12 resin accounts for 65%,the overall performance of the membrane is the best;the overall performance of the membrane prepared by using D001 resin is almost no difference.When the ratio of the 001�7 type resin was 67%,the film prepared when the film was prepared to have a ratio of 001�12 resin to 65%,the overall film performance was superior to that of the commercial film.As membrane performance indicators increase,it is increasingly difficult to further improve membrane performance during membrane preparation,and as one of the properties increases,it affects another performance.Compared with commercial membranes,there is an upper limit to the membrane performance that can be improved by the membrane preparation process.To further improve the membrane performance,a membrane modification method is required.In the process of membrane modification,the immersion solution not only forms a uniform and dense protective layer on the surface of the membrane,but also immersed in the interior of the membrane to form a compact composite network structure with the original membrane skeleton.Scanning electron microscopy analysis showed that the surface of the original film was magnified 5000 times.The surface of the film was smooth and uniform.The whole film was dense and without holes.After the original film was treated with 1%H₂O₂solution,the surface of the film showed a uniform distribution of micron-sized pores.The surface of the film originally existed.The surface layer of the protective layer is dissolved,and the micropores on the surface of the membrane are enlarged to open one end of the membrane pore.When the modified membrane is magnified 5000 times,the surface of the membrane is uniformly distributed by the pretreated micropores,and the surface becomes smooth and dense.The immersion solution forms a uniform and dense new protective layer on the surface of the membrane while repairing the micropores on the surface of the membrane,and blocks large pores on the membrane surface.Comparing the FTIR spectra before and after the modified film,it was found that four PWA characteristic peaks appeared in the modified film,at 806,891,980,1080 cm-1,and at the same time,at 1100 cm-1,TEOS derived from TEOS was exhibited.O-Si stretching vibration peak,the existence of Si-O-Si stretching vibration peak caused the shift of PWA characteristic peak,and the absorption peak generated by-OH stretching vibration between 3400³600 cm-1 indicates that the modification experiment can be the effective PWA/PVA-TEOS copolymer is effectively grafted onto the film.After the oxidative treatment,the three films showed different degrees of"powdering"phenomenon,the micropores on the surface of the film expanded,the ion exchange capacity and migration number decreased,the membrane resistance increased,the chloride ion leakage rate increased,and the overall selective permeability decreased.The overall performance of the modified membrane is slightly reduced,the overall performance of the CEM-A3membrane is reduced,and the overall membrane of the product is greatly reduced.The modified membrane has the best structure and chemical stability,and the membrane structure can still maintain a dense state.The structure and chemical stability of the commercial membrane are the worst,the membrane structure becomes very loose,and the membrane structure and chemical stability of CEM-A3 are moderate.Membrane preparation experiments and membrane modification experiments have achieved the purpose of the experiment.When the heterogeneous cation exchange membrane is applied in harsh environments,the phenomenon of"powdering"is related to the structure and material properties of the membrane,so it cannot be avoided.It can only be used.New materials and membrane modification experiments try to eliminate this phenomenon.