Development of flat-sheet membranes for C1-C4 alcohols dehydration via pervaporation from sulfonated polyphenylsulfone (sPPSU)

Abstract

In this work, pervaporation membranes made of sulfonated polyphenylsulfone (sPPSU) materials were developed and applied for C1-C4 alcohols dehydration. Compared to their non-sulfonated polyphenylsulfone (PPSU) counterpart, the membranes from sulfonated materials can achieve both a higher permeability and a higher selectivity. Fundamentals of PPSU membranes with different degrees of sulfonation are investigated by employing different analytic instruments. Polymer chains of sPPSU membranes get stiffer than those of PPSU membrane due to the favorable interaction between -SO3H groups. Moreover, sPPSU membranes maintain the similarly excellent mechanical properties and display slightly higher hydrophilicity compared with non-sulfonated PPSU membrane. The pervaporation characteristics and the temperature dependence of sPPSU membranes are examined with respect to the dehydration of an ethanol/water mixture. It is found that, for sPPSU membranes, permeation flux and permeability increase while separation factor and selectivity decrease with an increase in temperature. Activation energies based on flux (EJ) and permeability (EP) are also found to rise with increasing degree of sulfonation, which reveal that dehydration performance of sPPSU membranes is more sensitive to operating temperature than that of PPSU membranes. Sorption analyses indicate that membrane separation performance is mainly attributed to the preferential diffusion of feed components through membranes. Dehydration of C1-C4 alcohols by pervaporation through these PPSU based membranes was subsequently studied. Interestingly, it can be observed that flux can be maintained above 30 g/m2h while separation factor follows the order of IPA > n-BuOH > EtOH > MeOH. Especially, it can reach to a separation factor above 11 at 60□ for methanol dehydration, which is better than most other polymeric membranes, indicating a great potential to be applied for methanol purification in the industry.