Effect factors, kinetics and thermodynamics of remediation in the chromium contaminated soils by nanoscale zero valent Fe/Cu bimetallic particles

Abstract

Nanoscale zero valent iron (nZVI) was used to remediation contaminated soil. But nZVI has poor stability and tends to agglomerate easily. In this work, nanoscale valent iron–copper bimetal (nZVI/Cu) was synthesized and characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS). The nZVI/Cu was applied to reduce hexavalent chromium at a concentration of 120mg/kg in contaminated soil. A number of factors, including nZVI/Cu dose, initial pH, time and temperature were assessed to determine their impact on the reduction of Cr(VI) in soils. Results showed that Cr(VI) reduction exceeded 99% at a pH of 5, temperature of 303K, and nZVI/Cu dose of 0.06g. The Cr(VI) reduction kinetics was consistent with the mechanism of Langmuir–Hinshelwood first order kinetic model. The thermodynamic parameters (ΔG0<0, ΔH0>0, ΔS0>0) showed that the reduction process of Cr(VI) was spontaneous and endothermic. Therefore, this work could provide a reference for remediation of Cr(VI) contaminated soil.