Composite NF membranes with anti-bacterial activity prepared by electrostatic self-assembly for dye recycle

Abstract

Abstract Composite nanofiltration (NF) membranes with anti-bacterial activity were prepared by electrostatic self-assembly. A novel composite (Ag+-PEI/ Cu2+-PEI/ Fe3+-PEI) was obtained by the chelate reaction of polyethylenimine (PEI) with metal ion, which constituted the main component of the separation layer of the prepared membrane. Three composite (Ag+-PEI/ Cu2+-PEI/ Fe3+-PEI) NF membranes prepared at optimized condition exhibited excellent permeability (121 L·m−2·h−1·MPa−1/71 L·m−2·h−1·MPa−1/ 73 L·m−2·h−1·MPa−1) and high rejection (96.5%/ 94.5%/ 91.6%) for acid fuchsin as well as low rejection (31.5%/ 27.5%/ 23.7%) for MgSO4. Meanwhile, the higher flux recovery ratio (FRR) of dye was observed for the Fe3+-PEI membrane (FRRFe=91.5%) than that for others ((FRRCu=83.2%) and (FRRAg=76.4%)). Furthermore, these three NF membranes also presented good hydrophilicity (59°/39°/35°), excellent anti-bacterial activity (up to 95% against E. coil and over 90% against S. aureus) and good long-term stability in our trails. These results were of great significance for dye recycle in industrial field.