High-Stability hydrophilic PEBA-based composite membrane for efficient pervaporation desalination

In this study, we synthesized and developed a novel desalination pervaporation (PV) composite membrane material. The matrix consisted of customized thermoplastic polyether block-amides (PEBA), and a hydrophilic interpenetrating chemical cross-linking structure was formed by the addition of polyethyleneimine (PEI) and ethylene glycol diglycidyl ether (EGDE) to make PEBA/PEI/EGDE/PTFE composite membranes. In order to improve the desalination performance, we investigated the effect of changing the ratio of PEI, EGDE and PEBA in the separation layer on the desalination efficiency of the composite PV membrane. Under the optimal conditions, the PEBA/PEI/EGDE/PTFE (M 4-1 ) composite membrane exhibited a water flux of 74.04 ± 0.79 kg/(m 2 ·h), and the salt rejection was maintained at 99.9 % in a 3.5 wt% NaCl solution at 70 °C. The M4-1 composite membrane also exhibited excellent acid-base stability, demonstrating salt removal rates after treatment in solutions at both pH = 2 and pH = 14, with removal exceeding 99.9 % in both cases after 360 h. Additionally, the measured water flux of the M 4-1 composite membrane was 39.84 ± 0.17 kg/(m 2 ·h) at 70 °C and a NaCl concentration of 20 wt%, highlighting its potential for treating high salinity solutions. This study presents a strategy of physical and chemical cross-linking of interpenetrating hydrophilic modified structures, which sheds light on the long-term stable operation of PV desalination membranes and lays the foundation for industrial applications in the concentration and purification of seawater or high salinity water under complex conditions.