Perchloroethene and Chromium Removal from Humic Acid-containing Groundwater by Zero-Valent Iron Systems

摘要

In zero-valent iron (Fe0) treatment systems, the copresence of humic acid and divalent cations was found to impose combined effects that differ from corresponding individual effects. This study investigated the reactions of Fe0 with humic acid-containing solutions in batch experiments using HPSEC, TEM, FTIR, and XPS analyses. The formation of soluble ironhumate complexes in monovalent cation solution suppressed iron precipitation on Fe0 surfaces, probably hindering contaminant removal by adsorption and co-precipitation. By contrast, the majority of humic acid formed large aggregates with metal hydrolyzed species in divalent cation solutions, which slightly reduced the removal rates of perchloroethene and chromium by blocking or out-competing the reactive sites for reduction.