Interfacially Polymerized zwitterionic Thin-Film composite membranes with AEPBS for enhanced pervaporation performance in alcohol dehydration

Abstract

The development of high-performance membranes for pervaporation applications requires the precise design and optimization of surface functionality to enhance water selectivity and transport efficiency. In this study, thin-film composite (TFC) membranes were modified using zwitterionic N-aminoethyl piperazine butane sulfonate (AEPBS) to improve separation performance. The functionalization process involved a two-step reaction: interfacial polymerization of polyethyleneimine (PEI) with trimesoyl chloride (TMC) followed by the covalent grafting of AEPBS. Fourier-transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) confirmed the successful incorporation of zwitterionic sulfonate groups, significantly altering the membrane surface chemistry and enhancing hydrophilicity, as evidenced by reduced water contact angles. Morphological analysis revealed an increase in surface roughness and layer thickness, attributed to the functionalization process. The AEPBS-modified membrane achieved exceptional pervaporation performance, with a permeation flux of 2267.84 ± 138.09 g/m²·h and a separation factor of 1364.47 during alcohol dehydration using 70 wt% isopropanol (IPA) feed at 25 °C. Systematic variation of AEPBS concentration and grafting time revealed optimal conditions at 0.2 wt% AEPBS and 1-minute grafting, achieving the highest pervaporation separation index (PSI) of 3.09 × 10⁶ g/m²·h. The membrane demonstrated robust performance under diverse operating conditions, including varying feed temperatures and water concentrations, and maintained consistent separation efficiency during 168 h of continuous operation. These findings validate the potential of AEPBS-modified membranes for industrial applications, particularly in energy-efficient alcohol dehydration processes.