Optimization of photo-Fenton process parameters on carbofuran degradation using central composite design

Carbofuran, one of the most toxic and biorefractory carbamate compounds, is widely used in insecticides in Taiwan (9-18% of total insecticides production per year). In the present study, a central composite design experiment was used to study the effect of photo-Fenton treatment on carbofuran solution and to optimize the process variables such as carbofuran concentration (1-100 mg L-1), H2O2 dosage rate (0.25-6 mg L-1 min(-1)) and Fe3+ dosage (1-50 mg L-1), which influenced the efficiency of carbofuran degradation and mineralization. The results indicated that all the variables investigated in this study had significant roles in the degradation and mineralization of carbofuran in solution. The carbofuran degradation and mineralization efficiencies were increased with increase in H2O2 dosage rate and Fe3+ dosage, and with decrease in carbofuran concentration. Furthermore, optimum values of both H2O2 dosage rate and Fe3+ dosage were found to shift to higher values as carbofuran concentration increased. Based on the model obtained in this study, optimum H2O2 dosage rate and Fe3+ dosage were found to be 4 mg L-1 min(-1) and 20 mg L-1, respectively, for 51 mg L-1 of carbofuran concentration. Under these conditions, carbofuran was completely removed within 30 min and coupled with 78% mineralization at the end of experiment.