Oxidative degradation and detoxification of aqueous carbofuran by membrane anodic Fenton treatment

Abstract

Anodic Fenton treatment (AFT), a new Fenton technology for the treatment of pesticide wastewater, has been reported previously. The substitution of an ion exchange membrane for the salt-bridge, an improvement to the practicality of the AFT without sacrificing treatment efficiency, has also been reported. The oxidative degradation by membrane AFT of carbofuran, a heavily used and toxic carbamate insecticide, was investigated in this study. The results show that the degradation kinetics of carbofuran with different initial concentrations obeys the AFT model, and the treatment efficiency increases with increasing initial concentration. Raising the treatment temperature can result in enhanced degradation of carbofuran in solution. The pseudo-activation energy of carbofuran by membrane AFT was estimated to be 7.66 kJ mol −1. The results also show that AFT treatment can effectively remove COD and dramatically improve the biodegradability of carbofuran in solution. GC/MS analysis found four degradation products, revealing that the carbamate branch and 3-C in the furan ring are the first and second attack targets of hydroxyl radicals. As shown by the toxicity assay, the fatal toxicity of carbofuran to earthworms can be totally removed. The degradation of carbofuran by AFT is also a detoxification process.