Pentachlorophenol reduction by Pd/Fe bimetallic nanoparticles: Effects of copper, nickel, and ferric cations

摘要

Bimetallic nanoparticles have been used for effective reduction of chlorinated compounds; however, the study of cation effect on degradation is limited. This study examined the effect of three selected cations normally co-present in soil and groundwater contamination sites on the degradation kinetics and removal efficiency of pentachlorophenol (PCP) by Pd/Fe nanoparticles. Degradation of PCP by Pd/Fe nanoparticles was carried out in aqueous solutions containing different cations in sulfate form, Na2SO4, CuSO4, NiSO4, and Fe2(SO4)3. respectively. The observed inhibitory effect of Na2SO4 on degradation of PCP was contributed to the existence of SO4~(2-) ions. Overcoming the inhibitory effect of SO4~(2-) ions, Cu~(2+), Ni~(2+), and Fe~(3+) could facilitate the degradation kinetics and efficiencies of PCP by Pd/Fe nanoparticles. XANES absorption spectra were performed to characterize their valences. The enhancement effect of Cu~(2+) and Ni~(2+) ions result from the presence of reduced forms of copper and nickel on Pd/Fe surfaces. The presence of reduced forms of copper and nickel on Pd/Fe nanoparticles were confirmed by ICP-MS analysis. The addition of Fe~(3+) ions caused a decrease in pH and can reasonably account for the enhancement seen in the PCP degradation pro cess. These observations lead to a better understanding of PCP degradation with Pd/Fe nanoparticles and can facilitate the remediation design and prediction of treatment efficiency of PCP at remediation sites.