Enhanced reactivity and mechanisms of copper nanoparticles modified green rust for p-nitrophenol reduction

Abstract

This paper describes the reduction of p-nitrophenol by green rusts (GRs) interlayered with common inorganic anions (Cl−, SO42− and CO32−). Modifying of GRs with zero-valent Cu nanoparticles (Cu0 NPs) can greatly enhance the reductive reactivity of GRs via the formation of a galvanic couple between the GRs and the Cu0 NPs, as confirmed by an increased corrosion current. The direct addition of Cu0 NPs excludes the possible formation of less active mono-valent Cu in the GRs/Cu2+ system. Oxidation of GRs does not occur upon the addition of Cu0 NPs, thus a decline in electron transfer from the oxidized GRs to the Cu0 NPs is avoided. The optimum Cu0 NPs loading on GRCl is 0.5% wt. The GRCl/Cu0 NPs retains high reactivity in the studied pH range from 7 to 10, while the presence of NO3−, PO43−, SO42−, CO32– and humic acid inhibits PNP reduction by the GRCl and GRCl/Cu0 NPs. The GRCl/Cu0 NPs system is less susceptible to the presence of CO32– and humic acid compared to the pure GRCl system due to the migration of the PNP reduction sites from the GRs to the Cu0 NPs. This work sheds light on a new strategy for enhancing GR-based materials for use in groundwater remediation.