How to fabricate a negatively charged NF membrane for heavy metal removal via the interfacial polymerization between PIP and TMC?

The potential toxicity of heavy metals arising from the discharge of industrial wastewater has become a serious public concern. Fabrication of a thin film composite (TFC) NF membrane with desirable rejection of heavy metal ions is an attracting route to solve this problem. Hereon, we proposed a facile strategy for fabricating a TFC NF membrane with excellent heavy metal removal. The ratio of PIP and TMC was greatly enlarged by decreasing the concentration of TMC to an exceptional low extent. Thus a polyamide film with weak electronegativity and small pore size was successfully constructed on an ultrafiltration substrate membrane. Comprehensive characterizations were adopted to reveal the micro-variation of the resulted NF membranes when regulating TMC concentration. The optimized membrane prepared only with PIP and TMC can exhibit a high pure water permeability of 14.6 L m(-2) h(-1) bar(-1), desirable rejection of over 98% against Ni2+, Zn2+, Cu2+, and > 92.7% against Cd2+. This performance could go beyond most of the reported candidates which were prepared with other complicated methods. The simplicity, low cost and scaling up feasibility of the current strategy is expected to well meet the requirements of industrial production of TFC NF membrane for heavy metal removal.