Removal of benzoylecgonine from water matrices through UV254/H2O2 process: reaction kinetic modeling, ecotoxicity and genotoxicity assessment

Benzoylecgonine (BE), the main cocaine metabolite, has been detected in numerous surface water andtreatment plants effluents in Europe and there is urgent need for effective treatment methods. In thisstudy, the removal of BE by the UV254/H2O2process from different water matrices was investigated. Bymeans of competition kinetics method, the kinetic constant of reaction between BE and the photogen-erated hydroxyl radicals (•OH) was estimated resulting in kOH/BE= 5.13 × 109M−1s−1. By-products andwater matrices scavengers effects were estimated by numerical modeling of the reaction kinetics for theUV254/H2O2process and validated in an innovative microcapillary film (MCF) array photoreactor and in aconventional batch photoreactor. The ecotoxicity of the water before and after treatment was evaluatedwith four organisms Raphidocelis subcapitata, Daphnia magna, Caenorhabditis elegans, and Vicia faba. Theresults provided evidence that BE and its transformation by-products do not have significant adverseeffects on R. subcapitata, while D. magna underwent an increase of lipid droplets. C. elegans was the mostsensitive to BE and its by-products. Furthermore, a genotoxicity assay, using V. faba, showed cytogenicdamages during the cell mitosis of primary roots.