Investigation of the degradation behaviour of Methamidophos under microwave irradiation

The microwave (MW) irradiation process has been developed to treat wastewater of methamidophos production. The different oxidants are used as catalyst. A variety of factors affecting MW degradation in the presence of oxidants were studied. The best degradation ratio of methamidophos can be obtained at the MW power of 750 W, with 0.05% amount of K2S2O8, irradiation time of 6 min and 1.0 Â 10À4 mol/L methamidophos as initial concentration. The pH value almost has no effect on degradation methamidophos. The degradation ratio of methamidophos surpassed 96% within 6 min MW irradiation in the presence of K2S2O8 in these optimal experimental conditions. The research on kinetics suggests that the process of treatment accords to the pseudo-first-order reaction. Simultaneously, UV/nano-TiO2 and UV/nano-TiO2/K2S2O8 photocatalytic oxidation degradations of methamidophos were investigated. The experimental results indicated that the method of MW degradation of organic pollutants in the presence of oxidant was an advisable choice for treating organic wastewaters for nonor low-transparent and fuscous dye wastewaters.

In conclusion, we have found that MW irradiation can greatly enhance the efficiencies of advanced oxidation processes on the degradation DES4048.3d 6/24/2009 12:15:43 of methamidophos. This finding should be very useful for applying oxidants-assisted MW irradiation on wastewater treatment as commercial MW devices are easily available nowadays. Acknowledgments The authors greatly acknowledge the Education Department of Liaoning Province Science Foundation (No. 2009R30 and No. 2007T053) of China for financial support. The authors also thank their colleagues and other students who participated in this work.