Thin film composite nanofiltration membrane with tannic acid-Fe(III) complexes functionalized CNTs interlayer toward energy efficient remediation of groundwater

Tailoring nanofiltration (NF) membrane with low scaling potential and high energy efficiency is of critical importance to its practical implementation for groundwater remediation. In this study, interfacial polymerization was performed on the surface of an intermediate layer of TA-Fe/CNTs coated polyether sulfone (PES) substrate to obtain a loose NF membrane (TFNi-x) with negative surface charges and optimized water transport path for selective permeation of scaling ions and higher water permeance. The obtained TFNi-10 intermediated with a moderate amount of CNTs (10 μg/cm2) exhibited 80.5 % higher selectivity of Ca2+ over SO42− and 156 % higher water permeance compared to the control TFC while maintaining a high PFOA rejection (∼97.3 %). For the gypsum scaling measurements, TFNi-10 showed better anti-scaling behavior and 40 % less pressure energy consumption for the same recovered water volume (2.2 L), resulting in the higher water recovery and lower energy cost of specific volume of the permeate. It was contributed by the synergistic effects of the strong affinity of TA-Fe to piperazine monomer and the gutter effect of TA-Fe/CNTs interlayer. Our results paved a new way of fabricating novel NF membrane with tailored intermediate layer for optimized interfacial polymerization to realizing groundwater remediation in a cost-effective manner.