Removal of hexavalent chromium from wastewater by chelating resin supported Fe/Cu bimetallic nanoparticles: Characterization, performance and mechanisms

In this work, Bimetallic Fe/Cu nanoparticles were successfully stabilized by chelating resin, which was specifically employed for the remediation of hexavalent chromium contaminated wastewater. Based on the characterization results, it was observed that the Fe/Cu bimetallic nanoparticles were uniformly and well distributed on the surface of the resin DOW M4195. The results demonstrated that the supported bimetallic Fe/Cu nanoparticles exhibited an excellent performance for Cr(VI) removal efficiency, reaching up to 99.4%. A series of factors, including initial pH, initial concentration of Cr(VI), co-exciting ions and humic acid were systematically evaluated to ascertain their respective impacts on Cr(VI) removal. The kinetics study followed intra-particle diffusion model demonstrated that both the adsorption and diffusion processes of Cr(VI) by the DOW M4195 resin played an important role in the overall removal of Cr(VI). The analytical results derived from XPS spectra at specific reaction times revealed the underlying removal mechanism of Cr(VI): Cr(VI) was adsorbed onto M-Fe/Cu due to the rich porous structure of the chelating resin DOW M4195. Additionally, the presence of the second metal, Cu, was found to significantly enhance the reduction performance of Fe0 and Fe(II) during the Cr(VI) removal process. The Cr(VI) removal mechanism was determined to involve a combination of physical adsorption, redox reactions and co-precipitation.