Reduced graphene oxide-NH ₂ modified low pressure nanofiltration composite hollow fiber membranes with improved water flux and antifouling capabilities

Reduced graphene oxide-NH ₂ (R-GO-NH ₂ ), a kind of amino graphene oxide, was embedded into the polyamide (PA) layer of nanofiltration (NF) composite hollow fiber membranes via interfacial polymerization to enhance the permeate flux and antifouling properties of NF membranes under low pressure conditions. In addition, it could mitigate the poor compatibility issue between graphene oxide materials and PA layer. To evaluate the influence of R-GO-NH ₂ on the performance of the NF composite hollow fiber membrane, SEM, AFM, FTIR, XPS and Zeta potentials were used to characterize the membranes. The results indicated that the compatibility and interactions between R-GO-NH ₂ and PA layer were enhanced, which was mainly due to the polymerization reaction between amino groups of R-GO-NH ₂ and acyl chloride groups of TMC. Therefore, salts rejection of the current membranes was improved significantly, and the modified membranes with 50 mg/L R-GO-NH ₂ demonstrated highest performance in terms of the rejections, which were 26.9%, 98.5%, 98.1%, and 96.1%, for NaCl, Na ₂ SO ₄ , MgSO ₄ , and CaCl ₂ respectively. It was found that with the R-GO-NH ₂ contents rasing from 0 to 50 mg/L, pure water flux increased from 30.44 ± 1.71 to 38.57 ± 2.01 L/(m ² .h) at 2 bar. What's more, the membrane demonstrated improved antifouling properties.