Constructing (reduced) graphene oxide enhanced polypyrrole /ceramic composite membranes for water remediation

Abstract

Electrically conductive membrane, acting as an electrode while separating, has already been demonstrated breakthrough performance in mitigating membrane fouling and improving contaminant removal. However, only a few works have reported about conductive ceramic membranes because of their poor conductivity. Herein, we developed a kind of highly conductive polypyrrole (PPy) coated ceramic membrane (CM) with excellent anti-fouling performance through incorporating graphene oxide (GO)/reduced graphene oxide (rGO). During the process, π-π interactions, hydrogen bond or electrostatic attractions occur between GO/rGO and pyrrole (Py), leading to the adsorption of Py onto the GO/rGO rather than polymerizing directly on membrane surface, which effectively improve the membrane properties such as flux, porosity, hydrophilicity, Zeta potential, and roughness, etc. Particularly, due to the formation of a complete conductive network between PPy and CM with GO/rGO, as well as high conductivity of rGO, the electrical resistivity of PPy membrane was decreased from 8.46 to 3.56 and 0.87 kΩ/cm, respectively. Interestingly, the average specific flux of rGO/PPy (GO/PPy) membrane under electric field was 47.5% (33.6%) higher than that of CM support during yeast filtration, showing strong promise in water remediation. In particular, the extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) theory proved that after introducing GO/rGO into PPy membrane, the enhanced hydrophilicity and Zeta potential, as well as the weakened roughness, led to more positive van der Waals, Lewis acid-base and electrostatic interfacial force, that was, better anti-fouling property, which indicated an extremely bright future in the design of anti-fouling membranes.