Kinetics and products of photo-fenton degradation of triazophos

Triazophos is a contaminant of wastewater at manufacturing facilities, and remediative treatment may be needed. While toxicity and persistence limit the effectiveness of biological and physicochemical methods, photo-Fenton processes are promising. UV-Fenton and solar-Fenton processes were applied to degrade triazophos. The optimum parameters were 50 mmol/L H2O2, 0.3 mmol/L FeSO4, and pH 3.0. The decomposition of triazophos by a photo-Fenton process followed first-order kinemics. At 30 C, the half-life of triazophos in a UV-Fenton process ranged from 9.1 min at 2.0 x 10(5) Lx to 27.3 min at 1.0 x 10(5) Lx. At 35 degreesC and with solar irradiation luminance, it ranged within 1.0 x 10(5) -1.2 x 10(5) Lx; the half-life of triazophos in the solar-Fenton process was 11.2 min. Five major degradation products, O,O-diethyl phosphorothioic acid, monoethyl phosphorothioic acid, phosphorothloic acid, 1-phenyl-3-hydroxy-1,2,4-triazole, and phenylsemicarbazine, were tentatively identified as their corresponding trimethylsilyl derivatives with a gas chromatography-mass spectrometer. The possible degradation pathway of triazophos was proposed. The results indicate the potential use of a solar-Fenton treatment for triazophos-contaminated water.