High permselectivity of networked PVA/GA/CS-Ag+-membrane for dehydration of Isopropanol

Using glutaraldehyde (GA) as the crosslinking agent, the polyvinyl alcohol (PVA)/GA/chitosan (CS)-Ag+ networked membrane having high mechanical strength could be readily obtained via blending the Ag+-chelated CS precursor with PVA, performing excellent permeability and selectivity for the dehydration of aqueous isopropanol (IPA) solution. The introduction of the silver ion for the PVA/GA/CS-Ag+ membrane could effectively facilitate the water flux without loss its selectivity and particularly show its importance for the dehydration of water/isopropanol system under lower water percentage in feed, which is more favorable for high degree of propanol purification applications. Based on the membrane prepared under the Ag+ content of 1.17 x 10(-2) mol., we demonstrated that the highest flux of 1.97 kg/m(2) h accompanied with a separation factor up to 89991 could be achieved for the pervaporation dehydration of an isopropanol solution with the concentration of 90 wt % under a temperature of 30 degrees C. X-ray diffraction (XRD) was used to examine the existence of the sliver ion and its compatibility with polymeric matrix, and Fourier transform infrared spectroscopy (FTIR) enables the formation of networked structure to be detected, which can also reflect in the cross section morphology of the membranes observed using scanning electron microscopy (SEM). Effect of GA and the silver ion on the thermal-resistance of the resultant membrane was evaluated using thermogravimetric analysis (TGA). Membranes prepared using different compositions in response to hydrophilicity and mechanical strength were respectively evaluated by means of contact angle measurements and tensile strength tests.