Water Science & Technology: Water Supply—WSTWS Vol 10 No 1 pp 1–6 © IWA Publishing 2010 doi:10.2166/ws.2010.777

Degradation of chlorpyriphos in water by advanced oxidation processes

R. Murillo, J. Sarasa, M. Lanao and J. L. Ovelleiro

The degradation of chlorpyriphos by different advanced oxidation processes such as photo-Fenton, TiO₂, TiO₂/H₂O₂, O₃ and O₃/H₂O₂ was investigated. The photo-Fenton and TiO₂ processes were optimized using a solar chamber as light source. The optimum dosages of the photo-Fenton treatment were: [H₂O₂]=0.01 M; [Fe^3 + ]=10 mg l^-1; initial pH = 3.5. With these optimum conditions total degradation was observed after 15 minutes of reaction time. The application of sunlight was also efficient as total degradation was achieved after 60 minutes. The optimum dosage using only TiO₂ as catalyst was 1,000 mg l^-1, obtaining the maximum degradation at 20 minutes of reaction time. On the other hand, the addition of 0.02 M of H₂O₂ to a lower dosage of TiO₂ (10 mg l^-1) provides the same degradation. The ozonation treatment achieved complete degradation at 30 minutes of reaction time. On the other hand, it was observed that the degradation was faster by adding H₂O₂ (H₂O₂/O₃ molar ratio = 0.5). In this case, total degradation was observed after 20 minutes.

Keywords: hydroxyl radical; organophosphorous pesticide; ozone; peroxone; photo-Fenton; titanium dioxide

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