Abstract:Zwitterionic diamine monomer N-aminoethyl piperazine propyl sulfonate (AEPPS) was incorporated into hyperbranched polyamide nanofiltration membranes by reacting with trimesoyl chloride (TMC) via inter-facial polymerization to improve the performance of the membranes. The effect of AEPPS concentration on the performances of the membranes were systematically evaluated. Different from the results reported about AEPPS in conjunction with piperazine or m-phenylenediamine, when using AEPPS and hyper-branched polyamide mixture as aqueous reactants, the desalination order of the prepared membranes changed from Na2SO4 > MgSO4 > MgCl2 > NaCl to MgSO4 > MgCl2 ≈Na2SO4 > NaCl and then to MgSO4 > Na2SO4 > MgCl2 > NaCl by increasing AEPPS concentration. Salt rejection rate first increased and then de-creased, while membrane flux showed the opposite trend. The hydrophilicity and anti-fouling properties of the membranes were enhanced by introducing AEPPS into the membranes. When concentration of AEPPS was 0.6 %, the prepared nanofiltration membrane NF06 showed excellent anti-fouling properties. After it being circulated in bovine serum protein or lysozyme pro-tein solution for three times, the flux recovery rates were 99.3% and 99.4% respectively.