Photocatalytic water treatment on TiO2 thin layers

Abstract

Photocatalysis is generally applied as a suitable technique for water decontamination and/or purification, especially for decomposition of endocrine disruptors. Endocrine disruptors are commonly present not only in wastewater but also in natural water. Endocrine disruptors are persistent to degradation by common chemicals as well as biological and photolytic processes. Decomposition of three representative endocrine disruptors (17-ethynyl estradiol, bisphenol A, and 4-nonylphenol) was tested on previously prepared TiO2 photocatalyst in two types of reactors; a batch reactor and a plug-flow reactor. TiO2 thin layers deposited on three various substrates were prepared by a sol–gel process with employment of a dip-coating technique for subsequent application. Properties of the prepared layers were thoroughly characterized by XRD, SEM, AFM, UV–vis, and Raman spectroscopy. Photo-electrochemical properties were determined by linear voltammetry and amperometry to obtain photoinduced properties of the prepared TiO2 photocatalyst which corresponded to the photocatalytic activity. Photocatalytic decomposition efficiency was evaluated with respect to individual compounds for both reactors together with values of toxicity and estrogenic activity during the photocatalytic decomposition process. Furthermore, resistance of individual compounds to the photocatalytic decomposition process was evaluated together with possible formation of intermediates or by-products.