Fenton-Like Soil Remediation Catalyzed by Naturally Occurring Iron Minerals

Abstract

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