High-performance nanofiltration membrane prepared by dopamine-assisted interfacial polymerization on PES nanofibrous scaffolds

Thin-film nanofiltration composite (TFNC) membrane with high performance was demonstrated in this work. The membrane consisted of dopamine-modified polyethersulfone (PES) nanofibrous supporting layer and interfacially polymerized polyamide selective barrier layer. PES nanofibrous scaffold was modified with dopamine through self-polymerization. Here, dopamine was introduced to facilitate the formation of ultra-thin TFNC membrane on PES substrate with high performance and enhance the interfacial compatibility and structural stability of the composite membrane. An ultra-thin selective layer was generated by interfacial polymerization reaction between solutions of piperazine and trimesoyl chloride on the dopamine-modified porous PES membrane. Various parameters in interfacial polymerization, including monomer concentration, curing temperature, and curing time, were discussed and optimized to achieve high-performance composite nanofiltration membrane. The resulting TFNC membrane possessed relative high salt rejection (~99.4%) and high flux (~63.0 L/m2 h) to Na2SO4 solutions at a low pressure of 0.6 MPa, doubling the flux of TFNC membranes prepared at the same conditions, but without dopamine modification. It is believed that dopamine modification offers an efficient route for the fabrication of composite nanofiltration membranes with high filtration performance.