Competitive Removal of Two Contaminants in a Goethite-Catalyzed Fenton Process at Neutral pH

Abstract

Abstract

Plumes containing more than one contaminant can be found in sites polluted by gasoline or chlorinated solvents. This study evaluated Fenton-like removal efficiencies when two contaminants were coexistent. Perchloroethylene, trichloroethylene, cis-1,2-dichloroethylene, methyl-t-butyl-ether, benzene, and toluene were mixed in pairs and degraded by the goethite-catalyzed Fenton-like reaction at neutral pH and low H₂O₂ doses. Results revealed that the amount of each compound removed in two-contaminant systems was less than that in one-contaminant systems. This decline in removal was related to the reactivity constant (k_HO.), initial concentration (C₀), and number of double bonds of the compounds. In a solution that contained two compounds with similar k_HO. values, the amount of each compound removed was related primarily to the C₀ ratio of two compounds. When the k_HO. values of two compounds differed considerably, the one with the larger k_HO. value or the higher C₀ reduced or inhibited the Fenton-like reaction of the pollutant with the smaller k_HO. or lower C₀. Compounds with few double bonds tended to be less competitive for Fenton-like removal. By adding H₂O₂ repeatedly, the removal of a compound that is less competitive for the Fenton-like reaction can be recovered.