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.

Keywords:

• Water purification
• Photocatalysis
• Endocrine disruptor
• TiO₂ layers

Acknowledgment

The financial support of the Technology Agency of the Czech Republic No. TA01020804 and National Feasibility Program I (project LO1208 “TEWEP”) from Ministry of Education, Youth and Sports of the Czech Republic is gratefully acknowledged.

Notes

Presented at the 12th International Conference on Protection and Restoration of the Environment (PRE XII) 29 June–3 July 2014, Skiathos Island, Greece