High-performance zwitterionic TFC polyamide nanofiltration membrane based on a novel triamine precursor

Abstract

As known, piperazine (PIP) and m-phenylenediamine (MPD) are popularly employed as aqueous monomer to interfacially polymerize with trimesoyl chloride (TMC) for the fabrication of TFC polyamide NF and RO membrane, respectively. In this work, we designed a novel amine monomer 4-(piperazin-1-yl)benzene-1,3-diamine (PMPD) having the combined PIP and MPD units in one molecule and employing it with TMC to prepare the pristine nanofiltration membrane. Subsequently, zwitterionic antifouling PA surface was constructed by modification with 3-bromopropionic acid (3-BPA). The resulting membrane (PMPD-PA) exhibited a smoother surface with enhanced surface hydrophilicity than the membrane made from MPD, and the thickness of the PA active layer was down to ~35 nm. Meanwhile, its pure water permeability was ~19 L m−2 h−1 bar−1, with Na2SO4 rejection of 98.4%, and NaCl rejection as low as 24.1%, performing as a novel selective NF membrane. Furthermore, fouling tests using model foulants BSA and SA well illustrated the good antifouling properties of membrane PMPD-PA with the mitigated flux decline and enhanced flux recovery upon physical cleaning. Thus, this work further demonstrates the fabrication of high-performance TFC NF membrane from the perspective of molecular design.