In-situ Construction of Water Capture Layer Through Reaction Enhanced Surface Segregation for Pervaporation Desalination

Membranes with dense water capture layer and porous support layer hold great promise for achieving high flux in pervaporation desalination. Such membranes are usually fabricated by two-step methods, which often suffer from poor interfacial compatibility and membrane pore blockage. Herein, we fabricated a hetero-structured membrane with a dense water capture layer and a porous support layer in one step by reaction enhanced surface segregation (RESS) method. During the fabrication of polyether sulfone (PES) support layer via non-solvent induced phase separation (NIPS) process, the amphiphilic copolymer F127 in the casting solution and tannic acid (TA) in the coagulation bath migrated and reacted rapidly to each other, in-situ forming a TA-F127 water capture layer. The composition and structure of the water capture layer were tuned by controlling F127 content, TA concentration and reaction time. The optimal flux of 49.04 kg m(-2) h(-1) with the rejection of 99.99% was realized when treating 3.5 wt% NaCl solution at 70 degrees C. The membrane showed great adaptability for treating different concentrations of saline water. This study may provide a facile and scalable method for fabricating heterostructured membranes toward efficient desalination.