Degradation of chlorpyrifos, cypermethrin and chlorothalonil pesticides in aqueous solution by FeGAC/H₂O₂ process

Abstract

This study examined the degradation of pesticide aqueous solution containing chlorpyrifos, cypermethrin and chlorothalonil by the FeGAC/H₂O₂ process. Under the operating conditions (FeGAC 5 g/L, H₂O₂ concentration 100 mg/L and pH 3), chemical oxygen demand (COD) and total organic carbon removal were 96.2 and 79.2%, respectively, and biodegradability (BOD₅/COD ratio) increased from 0 to 0.40 after 60 min reaction. Complete degradation of chlorpyrifos, cypermethrin and chlorothalonil pesticides active ingredients occurred in 1 min. Kinetic models such as pseudo-first-order, pseudo-second-order and intraparticle diffusion were evaluated. The Fourier transform infrared spectra (treated and untreated pesticide aqueous solutions) also indicated modification and/or degradation of the pesticide organic bonds. The study showed that FeGAC/H₂O₂ process can be used for the pretreatment of pesticide aqueous solution containing chlorpyrifos, cypermethrin and chlorothalonil before further treatment by biological process.

Keywords:

• Pesticide
• Aqueous solution
• Degradation
• FeGAC/H₂O₂ process
• Kinetics

Acknowledgement

The authors are thankful to the management and authorities of the Universiti Teknologi PETRONAS, Malaysia for providing facilities for this research.