Fenton-Like Soil Remediation Catalyzed by Naturally Occurring Iron Minerals

Abstract

The ability of the iron minerals hematite and magnetite to catalyze the decomposition of hydrogen peroxide (H2O2) and initiate the Fenton-like oxidation of pentachlorophenol (PCP) was investigated in batch, bench-scale systems in which PCP was spiked onto silica sand. Pentachlorophenol degradation was documented in silica sand–mineral–H2O2 systems by the release of chloride and the loss of total organic carbon. The most efficient oxidation stoichiometry was the magnetite-catalyzed reaction over the first 8 h with 490 mol H2O2 consumed/mol PCP degraded. After 8 h, the peroxide efficiency decreased significantly; amorphous iron hydroxide formation on the magnetite surface may have catalyzed the decomposition of H2O2 to oxygen species other than hydroxyl radicals. Mineral-catalyzed Fenton-like treatment in two natural soils was demonstrated after spiking the soils with PCP; the contaminant was degraded with no iron addition. The oxidation stoichiometry in the two soils was 1,100 and 2,930 mol H2O2 consumed/mol PCP degraded. Key words: Advanced oxidation processes; Fenton's reagent; hydrogen peroxide; iron oxyhydroxides; pentachlorophenol; soil remediation