Structural optimization of separation layer and porous PES substrate for enhanced pervaporation desalination performance

Abstract

Pervaporation membranes with water-selective properties hold great potential for desalination and brine concentration applications. In this study, a modified PES porous membrane with smaller pore sizes and enhanced interfacial support was used as the substrate. Ultrathin selective layers were fabricated on its surface via atomized spray coating, resulting in high-performance pervaporation membranes for desalination analysis. The study compares the effects of PVA and PEI on membrane performance under different crosslinking systems. At 82 °C, using a 3.5 wt.% sodium chloride solution, the PES composite membrane with a PEI/SPTA selective layer achieved a maximum flux of 180.35 ± 13.8 kg m^-² h⁻¹, with a salt rejection rate of 99.97% ± 0.2. Even at a higher brine concentration of 20 wt.%, the membrane maintained a flux of 49.77 ± 7.3 kg m^-² h⁻¹ at 72 °C. The membrane's high salt rejection and stable performance under complex operating conditions demonstrate that pervaporation composite membranes prepared with low-surface-porosity substrates offer enhanced cycle stability and industrial potential in real-world desalination and concentration applications.