Optimizing interfacial polymerization with UV-introduced photo-fries rearrangement for enhancing RO membrane performance

To conveniently and environmentally friendly improve the performance of polyamide thin film composite (PA-TFC) membrane, a novel method associated with UV was presented in this study. In the process of the interfacial polymerization (IP), the UV irradiation procedure was performed to initiate photo-Fries rearrangement of PA, optimizing the membrane properties (i.e. thickness, membrane charge, hydrophilicity), and enhancing the membrane performance (i.e. permeability, selectivity, and anti-fouling performance). In comparison with the virginal PA-TFC membrane (virgin-RO), the resulting membrane (UV-13) exhibited an increased water flux of 75.9 L/m2·h (LMH, increased by 15.5%), and NaCl rejection of 99.34% (increased by 0.87%). Especially, the selectivity of UV-13 was dramatically enhanced, which can be concluded from that the salt permeability coefficient of UV-13 (5.04 × 10-4 m/h) is only half of that of virgin-RO (10.21 × 10-4 m/h). Furthermore, a series of membranes were fabricated by changing MPD concentration, TMC concentration and IP duration, and the corresponding separation performance were enhanced more or less, which may demonstrate that UV irradiation has the potential to be widely applied for enhancing PA-TFC RO membrane performance. Furthermore, UV-13 presents enhanced antifouling performance in comparison of virgin-RO, according to the results of artificial pollution tests of bovine serum albumin (BSA) and lysozyme (LYZ). Theoretically, for the RO membranes synthesized via IP process with aromatic amine monomers and aromatic acyl chloride monomers, this method is able to effectively improve the membrane performance, and has enormous potential in industrialization.