Oxidation of benzophenone-3 in aqueous solution by potassium permanganate: kinetics, degradation products, reaction pathways, and toxicity assessment

Abstract

Benzophenone-3 (BP-3) is used in a wide range of personal care products and plastics to resist ultraviolet light, which has aroused considerable public concern due to its endocrine-disrupting effects. In this work, we systematically investigated the chemical oxidation process of BP-3 by KMnO4. The influences of several factors, such as pH, oxidant dose, temperature, coexisting water constituents, and water matrices, on BP-3 degradation efficiency were evaluated. The removal rate of 10 μM BP-3 could reach 91.3% in 2 h under the conditions of pH = 8.0, [BP-3]0:[KMnO4]0 = 1:20, and T = 25 °C, with the observed rate constant (kobs) value of 0.0202 min−1. The presence of typical anions (Cl−, NO3−, SO42−) and HA could slightly increase BP-3 removal, while HCO3− caused a relatively significant promotion of BP-3 degradation. On the basis of mass spectrometry and theoretical calculations, hydroxylation, direct oxidation, and carbon–carbon bridge bond cleavage were mainly involved in the oxidation process. Toxicity assessment revealed that the acute and chronic toxicities were reduced significantly, which suggested KMnO4 is a promising technique for BP-3 removal.