Effects of various ions on the dechlorination kinetics of hexachlorobenzene by nanoscale zero-valent iron

► The degradation kinetics of HCB by NZVI is not affected by HCO3-, Mg2+, and Na+. ► Cl− and SO42- enhance the degradation reaction due to their corrosion promotion. ► NO3- competes with HCB so it inhibits the degradation reaction. ► Cu2+ enhances degradation of HCB resulted from the reduced form of Cu on NZVI. ► Fe2+ inhibits the degradation reaction due to passivation layers formed. The effect of several anions and cations normally co-present in soil and groundwater contamination sites on the degradation kinetics and removal efficiency of hexachlorobenzene (HCB) by nanoscale zero-valent iron (NZVI) particles was examined. The degradation kinetics was not influenced by the HCO3-, Mg2+, and Na+ ions. It was enhanced in the presence of the Cl− and SO42- ions due to their corrosion promotion. The NO3- competes with HCB so it inhibits the degradation reaction. The Fe2+ ions would inhibit the degradation reaction due to passivation layer formed, while it was enhanced in the presence of Cu2+ ions resulted from the reduced form of copper on NZVI surfaces. These observations lead to a better understanding of HCB dechlorination with NZVI particles and can facilitate the remediation design and prediction of treatment efficiency of HCB at remediation sites.