Study On Preparation And Pervaporation Performance Of Silicalite-1/PDMS Nano-hybrid Composite Membrane

The selective removal of alcohol from water by pervaporation (PV) has receivedgreat attention over the years, due to the widespread application of fuel ethanol. As apromising separation process, PV has been considered to be a preferable alternative todistillation, because of its low energy consumption, optimized integration withfermentation, economical competition and improved the efficiency of fermentation.However, the PV ethanol perm-selective membrane with high flux, high selective andgood stability is the key and core of PV technology. Now, most researches on ethanolperm-selective membrane were concentrating on PDMS modification and preparationof PDMS hybrid composite membrane.In this paper, PDMS was used as separation material, the Silicalite-1/PDMSnano-hybrid composite membranes have been prepared on organic plate base (PS) andinorganic tubular base (Al2O3) respectively, through adding different modifiedSilicalite-1crystals. Their pervaporation performances on alcohol/water mixtureshave been studied.Firstly, the four different sizes of Silicalite-1crystals have been synthetizedthrough hydrothermal method, and modified by three silane coupling agents, theircharacteristics of structure, morphology and modification have been studied. TheSilicalite-1/PDMS plate hybrid composite membranes have been prepared on PS baseby wiped film method, the influences of Silicalite-1crystal size, content and differentmodification on membranes PV performance have been studied. We explored theinfluence of operating conditions on N-Silicalite-1/PDMS plate hybrid compositemembrane PV performance. The results indicate that the plate hybrid compositemembrane with TMDS modified100nm Silicalite-1crystal has the best PVperformance, The total permeation flux and the separation factor for ethanol could be400g/(m2·h) and14.7, respectively, when the feed concentration was5%and the feedsolution temperature was60℃.In order to improve the flux of hybrid composite membrane and expand theirapplications, the Silicalite-1/PDMS tubular hybrid composite membrane has beenprepared on Al2O3ceramic base through sol-gel dip-coating method. Firstly, weinvestigated the influence of sol-gel dip-coating conditions and PDMS content ontubular hybrid composite membrane PV performance, and confirmed the best preparation condition. Compared with industrialized ZSM-5crystals, we found thatSilicalite-1/PDMS tubular hybrid composite membrane shows higher selective factor,and ZSM-5/PDMS tubular hybrid composite membrane shows higher total flux. Theinfluences of Silicalite-1content and operating conditions on membranes PVperformance have been studied. The results indicate that the total permeation flux andthe separation factor for ethanol of Silicalite-1/PDMS tubular hybrid compositemembrane could be1100g/(m2·h) and10.3, respectively, when the feed concentrationwas5%and the feed solution temperature was60℃. Furthermore, theN-Silicalite-1/PDMS tubular hybrid composite membrane PV performances ondifferent alcohol/water solution have been researched, the total permeation flux andthe separation factor for n-butyl alcohol could be780g/(m2·h) and50, respectively.