Preparation and performance of antibacterial layer-by-layer polyelectrolyte nanofiltration membranes based on metal-ligand coordination interactions

The coordination interaction between transition metal Cu2+ ions and polyelectrolyte (PE) ligands is studied to prepare (PEI/PSS(Cu)(1/2))(n) layer-by-layer (LBL) self-assembly (SA) nanofiltration (NF) membranes with unique antibacterial properties. The coordination interaction mechanism has been clearly illustrated by X-ray photoelectron spectroscopy (XPS) analysis of the chemical composition of the active skin layer, and the result reveals that about one third of the Cu2+ ions are involved in the interaction. The prepared (PEI/PSS(Cu)(1/2))(5) LBL membrane has relatively smooth surface morphology and good separation performance, with a permeation flux of 65 L m(-2) h(-1) and rejection of about 84% for SO42- at 1.0 MPa. It has an excellent antibacterial rate up to 94.2%. The performance of the LBL membranes could be improved, after cross-linking by glutaraldehyde (GA). This kind of LBL NF membrane shows potential application in the separation of monovalent and divalent anions.