Comparative studies on decomposition of selected estrogens and xenoestrogens by photocatalysis processes

Abstract

This study addressed the degradation efficiency of three different compounds belonging to the group of endocrine disrupting compounds (EDCs), namely 17 -estradiol (E2), 17 -ethinyl estradiol (EE2), and bisphenol A (BPA) in the photocatalysis process (UV/TiO2). The subject of the study was a synthetic municipal waste water treatment plant effluent containing inorganic and optionally organic substances and to which the investigated micropollutants were added at a concentration of 500 g/dm. The obtained results were compared in terms of the degradation of the selected compounds in deionized water. It was found that the efficiency of the photocatalysis depends significantly both on the environmental matrix and physico-chemical properties of the compounds present in the treated waste water. The highest degradation efficiency was observed for the synthetic effluent that contained only inorganic substances. The degradation of bisphenol A and 17 -ethinyl estradiol exceeded 90 % (after 60-minute irradiation) and 17 -estradiol was decomposed completely. The observed phenomenon can be attributed to the process termed as sensitized photocatalysis, which was enabled by inorganic substances present in the synthetic waste water. This phenomenon was not observed for the synthetic effluent that contained both inorganic and organic substances, and moreover the degradation efficiency of the micropollutans was lower. These observations were also confirmed by the results regarding the decomposition of the compounds in deionized water. In order to describe the course of photocatalytic oxidation reaction rate constants were determined as well as degradation half-lives using the Langmuir-Hinshelwood kinetic model.