Photochemical degradation of carbofuran and elucidation of removal mechanism

Abstract

Carbofuran removal by the photo-Fenton reaction was investigated under various H(2)O(2) dosage rate (0-6 mg L(-1) min(-1)) and Fe(3+) dosage (5-50 mg L(-1)). The outcomes demonstrate that the photo-Fenton reaction was influenced by both the factors. An initial carbofuran concentration of 50 mg L(-1) was completely degraded within 30 min, and 93% dissolved organic carbon (DOC) removal was observed after 120 min of treatment at initial pH 3, H(2)O(2) dosage rate of 4 mg L(-1) min(-1) and Fe(3+) dosage of 35 and 50 mg L(-1). However, no significant improvement in the carbofuran removal was observed when the H(2)O(2) dosage rate and Fe(3+) dosage were increased beyond 4 mg L(-1) min(-1) and 35 mg L(-1), respectively. The carbofuran removal was fitted using the pseudo-first order reaction model and the highest apparent rate constant of 10.5 x 10(-2) min(-1) was obtained. Five major carbofuran intermediates were identified, which indicate that C-O bond of the carbamate group and 3-C position of the furan ring were oxidized as a result of the photo-Fenton reaction. (C) 2010 Elsevier B.V. All rights reserved.