Fabrication Of High Performance Composite Membrane Based On Surface Segregation And Adhesion For Pervaporation Dehydration

The water/ethanol mixture was chosen as the investigated system. Surfacesegregation method and phase inversion process and adhesion were introduced intofabricating composite membranes with enhanced structure stability and highseparation performance.CS/SPES-PES composite membrane was prepared by coating the chitosan （CS）active layer onto the sulfonated polyethersulfone （SPES）-polyethersulfone （PES）support layer. The SPES-PES support layer was prepared by blending withhydrophilic SPES into PES matrix in a wet phase inversion process. X-rayphotoelectron spectroscopy （XPS） characterization and water static contact anglemeasurements confirmed the surface segregation of SPES on the support layer, whichremarkably enhanced the adhesion between the active layer and the support layer.T-peel test results showed that the interaction strength at the interface ofCS/SPES-PES composite membrane was nearly5times higher than that of CS/PEScomposite membrane. A permeation flux of1394g m^-2h^-1with a separation factor of376was obtained when using the CS（6）/SPES（40-3）-PES composite membrane forpervaporation dehydration of a90wt.%ethanol aqueous solution at353K with aflow rate of60L h^-1and a pressure of0.33kPa at the downstream side of themembrane. The long-term stability study demonstrated that the structural stability andthe performance stability of the as-prepared membrane were notably improved byhydrophilic modification of the support layer surface.Polyacrylonitrile （PAN） as a support layer, Guar Gum （GG） and polycarbophil（PCP） as a transition layer respectively, glutaraldehyde cross-linked chitosan （CS） asan active layer, the composite membranes were prepared by sequential casting andspin coating method. There is no distinct boundary between active layer and transitionlayer and transition layer is very thin. A permeation flux of1011g m^-2h^-1with aseparation factor of1775was obtained when using the CS/GG（1wt.%）/PANcomposite membrane for pervaporation dehydration of a90wt.%ethanol aqueoussolution at353K with a flow rate of60L h^-1and a pressure of0.33kPa at thedownstream side of the membrane. And at the same conditions a permeation flux of1390g m^-2h^-1with a separation factor of1279was obtained for CS/PCP（0.05 wt.%）/PAN composite membrane. Furthermore, all the membranes displayeddesirable stability during the168h continuous operation.