| In this study,the polyethersulfone(PES)ultrafiltration membrane was surface functionalized with polydopamine(PDA)and 2-hydroxypropyl trimethyl ammonium chloride chitosan(HTCC)by layer-by-layer self-assembly to prepare(HTCC/PDA)3/PES amphoteric charged composite nanofiltration membranes.And then AgNPs were successfully attached to the membrane surface via the adhesion and in situ reduction of Ag+ by PDA to improve the antibacterial properties of the films.The effects of the concentration of casting solutions,the supporting salt,the oxidant of Cu2+,AgNO3 solution and the number of bilayers on the membrane performance were investigated.The structure and properties of the membranes were characterized by atomic force microscopy(AFM),scanning electron microscopy(SEM),fourier transform infrared spectroscopy(FTIR)and contact angle tests.The pure water permeability coefficient,the molecular weight cut off and the Zeta potential of the membrane were determined.The retention effects of inorganic salts and organic pollutants PPCPs,the stability and the antibacterial properties of composite membranes were also studied.It was found that when the dopamine solution was 4 g/L,the supporting salt was 0.075 g/L,the oxidant of Cu2+ was 4 g/L,and the number of bilayers was 3,an optimized(HTCC/PDA)3/PES amphoteric charged composite nanofiltration membrane could be obtained.The pure water permeability coefficient of the prepared membrane was 15.67 L·m-2·h-1·MPa-1.the molecular weight cut off was 935 Da,and the isoelectric point was 3.4.AFM and contact angle test indicated that the surface roughness and hydrophilicity of the composite nanofiltration membrane were improved.Characterization of microstructure by SEM showed that deposited polyelectrolytes in the pores of top-layer of the composite nanofiltration membrane resulted in a large reduction of the pore size,and also confirmed the presence of AgNPs on the membrane surface.Retention order of inorganic salts by(HTCC/PDA)3/PES membrane was K2SO4>Na2SO4>MgSO4>NaCl>KC1>MgC12.basically according with the characteristic of negatively charged membranes.The removal rate of Atenolol(ATE).Carbamazepine(CBZ)and Ibuprofen(IBU)by the composite membrane under the neutral condition were 76.22.87.29 and 89.85%.respectively.Under the response of pH,the rejection rates of ATE and IBU could be increased to 81.67%and 94.50%.respectively,indicating that the membrane surface was amphoteric.In addition.the static immersion and filtration experiments confinned that AgNPs were successfully immobilized on the(HTCC/PDA)3-AgNPs/PES membrane surface.and they were loaded the most firmly on the membrane prepared under 100 mM AgNO3 solution.And the prepared membrane exhibited excellent antibacterial activity against Escherichia coli by the antibacterial experiment. |
