Bioallethrin degradation by photo-Fenton process in acetonitrile/water and aqueous β-cyclodextrin solutions

Abstract

Bioallethrin (Bio) is an insecticide that chemically and functionally belongs to the family of the synthetic insecticides named pyrethroids. In this work the degradation of Bio is studied by the photo-Fenton and photo-Fenton-modified processes. The first one produces the complete mineralization of Bio in less than one hour of irradiation. However, due to the low solubility of Bio in water, different modifications of the photo-Fenton process were tested. First, the photo-Fenton process was carried out in mixtures of different acetonitrile/water proportions. Although acetonitrile deactivates the hydroxyl radical, the main oxidizing agent in the photo-Fenton process, a Bio degradation greater than 90% is achieved in 80 min of reaction. Second, degradation of Bio was evaluated by photo-Fenton in a medium with β-cyclodextrin (β-CD), where the Bio solubility could be increased at least thirty-five times. The association constant of Bio to β-CD was measured to be 1933 ± 300 M−1 and molecular simulation results indicate a 1:1 inclusion complex stabilized by the formation of intermolecular H-bonds. The Bio degradation rate in this medium was similar to that observed in aqueous media. The use of β-CD presents a friendly alternative to the environment for the degradation of the pyrethroid insecticide.