Dual-Functional Ultrafiltration Membrane for Simultaneous Separation and Degradation of Aquatic Micropollutants

Dual-functional ultrafiltration membrane for simultaneous separation and degradation of aquatic micropollutants

Xiaofeng Fang ^a,b, Dapeng Wang ^a, Jiansheng Li,^a*, Zhipeng Liao ^a, Qin Li ^a, Shunlong Pan ^a, Lianjun Wang ^a, Dionysios D. Dionysiou ^b*

^a Key Laboratory of Jiangsu Province for Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, China

^b Environmental Engineering and Science Program, University of Cincinnati, Cincinnati, OH, 45221-0071, USA

Abstract: Micropollutants in the aquatic environment have become a global concern because of their overall environmental toxicity. Membrane technology plays an important role in the removal of micropollutants, but there remain significant challenges such as concentration polarization, membrane fouling, and high energy consumption for nanofiltration (NF) or reverse osmosis (RO) membranes. The work reported here uses a dual-functional ultrafiltration (DFUF) membrane with rejection and catalysis functions for simultaneous removal of multiple pollutants from water. The main strategy is by blending tannic acid (TA) and Fe^III complexes in UF membrane matrix to in situ form Ag nanoparticles on inner pores and surface of polymeric membrane. The FESEM results show the nanoparticles are uniformly dispersed on the inner pore walls of the membrane and the diameters range from 5 to 20 nm. The obtained DFUF membrane exhibited maintainable pure water flux (239.8 L/m² h), ascendant bovine serum albumin (BSA) rejection (96.1%) and excellent humic acid (HA) rejection (87.3%). The catalytic performance was conducted with three paralleled experiments, i.e, dynamic catalysis, static catalysis and membrane-free catalysis. Compare to static catalysis and membrane-free catalysis, dynamic catalysis indicated significant catalytic performance with filtering aqueous solution containing humic acid and 4-nitrophenol(4-NP) through DFUF membrane. This is due to the eradication of the negative effect of HA on the reduction of 4-NP in dynamic catalysis mode. In this case, the HA can be rejected by membrane and shy away from the Ag NPs on the inner pores. The conversion rate of 4-NP was 98% for the catalysis of mixture solution (4-NP and HA) in dynamic mode. Furthermore, DFUF could be reused with high stability as they kept a high level than 95% for filtering the mixture solution over seven cycles. The results therefore demonstrate the DFUF membranes have good potential for removal of micropollutants.