pH-mediated polyethyleneimine-based thin-film composite membranes for high-performance pervaporation desalination

Pervaporation (PV) desalination has emerged as a promising seawater desalination technology, distinguished by its strong hydrophilicity and capacity to efficiently treat highly saline feeds. Advancing stable, high-performance PV desalination membranes to achieve robust and durable applications remains the central objective in this field. Herein, a pH-mediated strategy was proposed to prepare high-performance thin-film composite membranes for PV desalination based on the regulation of polyelectrolyte (polyethyleneimine, PEI, as the monomer in aqueous phase) during the interfacial polymerization process. Specifically, through adjusting the adsorption on the hydrolyzed polyacrylonitrile substrate and the reactivity of PEI with trimesoyl chloride (TMC), the physicochemical properties and the structure of the PEI-TMC based polyamide active layers were optimized. As a consequence, the resulting PEI-TMC membrane shows enhanced PV desalination performance (52.4 L m -2 h -1 water flux with 99.99% rejection for 3.5 wt% NaCl feed solution at 70°C), which is attributed to its appropriate crosslinking degree and thickness of the active layer. This work demonstrates the feasibility of tuning the PV performance of the polyelectrolyte-based membranes by regulating the protonation degree of the polyelectrolyte, highlighting its promising application potential.