Study of the degradation of the herbicide Isoxaflutole by different methods: PhotoFenton and sensitized photolysis

EDUARDO GATICA; JOSÉ NATERA ; SANDRA MISKOSKI; EDUARDO DE GERÓNIMO; WALTER MASSAD; NORMAN GARCÍA

Villa Carlos Paz

Congreso; Latin-American Meeting on Photochemistry and Photobiology (XIII ELAFOT); 2017

Inter-American Photochemical Society (I-APS)

Isoxaflutole (IXF) it is a pro-herbicide that hydrolyses spontaneously to diketonitrile (DKN) which is a compound phytotoxic with herbicidal activity. In this work, we present the study of the sensitized degradation of IXF using a typical environmentally friendly sensitizer like Riboflavin (Rf) and the processes of Fenton and foto-Fenton. Rf generates the oxidative species: singlet oxygen (O2(1Δg)) and superoxide anion (O2?) upon visible light irradiation and the degradation of the contaminants may be due to the reaction between the pollutant and the excited electronic states of the Rf or with the reactive oxygen species generated by these. Whereas in the Fenton and photo-Fenton process, the hydroxyl radical (HO?) is the main oxidant species. The photosensitized degradation by Rf is not a meaningful process, IXF quenches the 3Rf* with a rate constant of 1.5 107 M-1 s-1 and not the reaction is observed with the species O2(1g) and O2?- generated from 3Rf*. The photo-Fenton process, under typical conditions, produces the 88 % of mineralization for a 99% of IXF degradation and a rate constant value of 1.0 109 M-1s-1 was determined for the reaction between IXF and HO?. The degradation products were identified, by UHPLC-MS/MS analysis, for the photo-Fenton process.