Destruction of Chlorinated Phenols by Dioxygen Activation under Aqueous Room Temperature and Pressure Conditions

Abstract

The complete destruction of separate mixtures of 1.1 mM 4-chlorophenol (aqueous) and 0.61 mM pentachlorophenol (aqueous slurry) take place in the presence of 0.5 g of iron particles in 10 mL of 0.32 mM ethylenediaminetetraacetic acid (EDTA) under ambient air under room temperature conditions. Under this reaction condition, the time required to reach complete disappearance to the detection limit of GC-FID for each compound was 4 h for 4-chlorophenol and 70 h for pentachlorophenol. Electrospray ionization mass spectral (ESI-MS) analysis of the 4-chlorophenol reaction mixture after its complete disappearance indicated non-chlorinated, primarily low molecular weight products; however, Cl- from 4-chlorophenol was not detected due to adsorption onto the iron or its corrosion products. Radical trap and control experiments suggest that the mechanism for destruction initiates with dioxygen activation, leading to the formation of reactive oxygen species (ROS) and ultimately ring opening of the phenolic compounds. This is the first example of an abiotic system capable of the complete destruction of an organic pollutant under room temperature and pressure conditions through dioxygen activation chemistry.