Chitosan/Sulfonated Polyethersulfone-Polyethersulfone (CS/SPES-PES) Composite Membranes for Pervaporative Dehydration of Ethanol

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 with hydrophilic SPES into PES matrix in a wet phase inversion process. X-ray photoelectron spectroscopy (XPS) characterization and water static contact angle measurements confirmed the surface segregation of SPES on the support layer, which remarkably enhanced the adhesion between the active layer and the support layer. The effect of sulfonation degree and concentration of SPES on the structure and morphology of the resultant SPES-PES support layer was observed by field emission scanning electron microscope (FESEM). T-peel test results showed that the interaction strength at the interface of CS/SPES-PES composite membrane was nearly 5 times higher than that of CS/PES composite membrane. The effects of SPES presence in the support layer, annealing temperature, operating temperature, and feed concentration on the pervaporation performance for ethanol dehydration were investigated. A permeation flux of 1394 g/(m(2) h) with a separation factor of 376 was obtained when using the CS/SPES(40-3)-PES composite membrane for pervaporation dehydration of a 90 wt.% ethanol aqueous solution at 353 K. The long-term stability study demonstrated that the structural stability and the performance stability of the as-prepared membrane were notably improved by hydrophilic modification of the support layer surface.