PEI/SA/Cu ternary system modified positively charged nanofiltration membrane and its desalting performance
In this paper,sodium alginate(SA)and polyethylenimine(PEI)were blended as aqueous solution for secondary interfacial polymerization(SIP)reaction.The strong interaction between PEI and SA made SA embed into polyamide(PA)layer,thus improving the density of the membrane.Subsequently,the surface positive charge was improved through the complexation of Cu2 with SA and PEI,and the retention of polyvalent cations was improved.The effects of SA and Cu2+concentrations on physicochemical properties,surface morphology and separation performance of the composite membranes were studied.The results showed that the optimal membrane preparation conditions were as follows:SA concentration was 0.01％,Cu2+concentration was 25 mmol/L.The corresponding PS/Cu-3 composite membrane has enhanced hydrophilicity and density,and decreased pore size.Compared with Control-PEI membrane,its flux is increased by 257％to(40.0±0.8)L/(m2·h),and the rejection of MgCl2 is increased from 92.0％to 97.1％,and it has good pressure resistance and stability.
PEI/SA/Cu ternary system modificationpositively chargednanofiltration membranedesal-ting performance
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