Photodegradation of the acaricide abamectin: a kinetic study.

摘要: The acaricide abamectin is a mixture of two colorless homologues in molar ratio at least 4:1 with the same structure macrocyclic lactone. kinetics its degradation under direct (254 nm) and dye-sensitized (>400 photoirradiation methanol solution has been studied by UV−vis spectrophotometry, potentiometric detection dissolved oxygen, stationary fluorescence, laser flash photolysis, time-resolved singlet molecular oxygen (O2(1Δg)) phosphorescence. results indicate that very efficient irradiation UV light nm), quantum yield 0.23. On contrary, visible-light irradiation, using natural pigment riboflavin or synthetic dye rose bengal as sensitizers, inefficient proceeds through O2(1Δg)-mediated mechanism, bimolecular rate constant for overall O2(1Δg) quenching (the sum physical chemical quenching) 5.5 × 105 M−1 s−1. This value similar to those re...