Modulation of reduced graphene oxide membrane for low-fouling wastewater filtration: Membrane structure, wastewater property, and DFT calculation

Abstract

Membrane fouling is a major hurdle impeding real-world application of membranes for advanced wastewater treatment. In this study, a GO membrane and a reduced GO (rGO) membrane were examined in parallel for their anti-fouling propensities and ability to remove pharmaceutical compounds from realistic wastewater effluents. The effects of membrane properties and wastewater characteristics on the two aspects were also assessed by experiments and DFT simulation. The results showed that the transmembrane pressure (TMP) of the rGO membrane increased by 0–3.5 kPa after filtering a secondary wastewater effluent from an activated sludge system (SW), as compared to 201.6–292.1 kPa for the GO membrane. Meanwhile, slightly greater TMP increases were observed for both membranes after filtering a secondary wastewater effluent from a partial nitrification and denitrification system (PND), but the fouling remained low for the rGO membrane. Overall, chemical reduction of GO to rGO led to larger SSA and reduced negative charge, which promoted adsorptive filtration of pharmaceutical compounds. Also, the diminishing of functional groups possessed by the GO membrane mitigated attractive interlayer polar interaction and expanded membrane pore dimension, thus enhancing the permeability and anti-fouling propensity of GO membranes.