Petaloid N-doped reduced graphene oxide supported zero-valent iron as catalyst activated peroxydisulfate for effective oxidation of β-hexachlorocyclohexane

Abstract

Developing an efficient heteroatom-doped Fe-carbon catalyst is of great significance for the remediation of contaminated water and soil. In this study, a three-dimensional petaloid N-doped reduced graphene oxide (N-rGO)-supported nanoscale zero-valent iron (nZVI) composite (nZVI@N-rGO) was successfully prepared and applied to activate peroxydisulfate (PDS) to remove typical organochlorine pesticides (OCPs) from contaminated water and soil. The results indicated that N doping not only restructured the surface morphology of rGO and generated a petaloid nanosheet structure but also introduced additional defect sites for the loading of nZVI. nZVI@N-rGO effectively activated PDS to degrade β-hexachlorocyclohexane (β-HCH) in aqueous solution and contaminated soil. Characterization of the reaction process revealed that SO4∙-, •OH, 1O2 and O2∙- were the reactive species involved in β-HCH degradation and that the abundant N-doped sites and high conductivity of nZVI@N-rGO promoted the generation of reactive species and mediated direct electron transfer. Furthermore, the petaloid structure of N-rGO allowed for greater contact of PDS and β-HCH with nZVI, which improved the mass transfer of reactants. nZVI@N-rGO has good adaptability to different anions, humic acid concentrations and pH conditions in water. This work provides the necessary inspiration and guidance for the practical application of Fe-Carbon catalysts in the remediation of water and soil contaminated by OCPs.