Positively charged thin film composite nanofiltration membrane via layer-by-layer interfacial polymerization based on PU nanofibrous support

Abstract

Positively charged Nanofibrous nanofiltration (NF) membranes were prepared via multi-step interfacial polymerization from polyethylenimine (PEI) and terimesoyl chloride (TMC) on a polyurethane (PU) nanofibrous support. In this way, electrospinning technique was applied for preparation of the PU nanofibrous support and at the following, NF membranes were formed via layer-by-layer interfacial polymerization and the cycle of sequential depositions. The nanofibrous NF membranes were characterized using ATR-FTIR, surface charge, morphology, MWCO, capillary flow porometery and NF performance techniques. Moreover, the effect of the reaction cycle number on NF performance was evaluated. The result of NF membrane prepared by three cycles of reactions with 1.5 wt% PEI and 0.5 wt% TMC presented appropriate salt rejection and flux; 99.1% for MgCl2, 82.3% for MgSO4, 81% for NaCl and 57.1% for Na2SO4 and electrolyte permeate flux; 70 L/m2 h for MgCl2, 73 L/m2 h for MgSO4, 72 L/m2 h for NaCl and 74 L/m2 h for Na2SO4 under filtration pressure of 8 bar. At the end, the performance of positively TFNC-NF membrane was compared with other positively nanofiltration membranes.