Photocatalytic ozonation using doped TiO2 catalysts for the removal of parabens in water

João F Gomes; Inês Leal; Katarzyna Bednarczyk; Marta Gmurek; Marek Stelmachowski; Magdalena Diak; M Emília Quinta-Ferreira; Raquel Costa; Rosa M Quinta-Ferreira; Rui C Martins

doi:10.1016/j.scitotenv.2017.07.180

Photocatalytic ozonation using doped TiO₂ catalysts for the removal of parabens in water

Sci Total Environ. 2017 Dec 31:609:329-340. doi: 10.1016/j.scitotenv.2017.07.180. Epub 2017 Jul 25.

Affiliations

¹ CIEPQPF - Chemical Engineering Processes and Forest Products Research Center, Department of Chemical Engineering, Faculty of Sciences and Technology, University of Coimbra, Rua Sílvio Lima, 3030-790 Coimbra, Portugal. Electronic address: jgomes@eq.uc.pt.
² CIEPQPF - Chemical Engineering Processes and Forest Products Research Center, Department of Chemical Engineering, Faculty of Sciences and Technology, University of Coimbra, Rua Sílvio Lima, 3030-790 Coimbra, Portugal.
³ Faculty of Process and Environmental Engineering, Department of Safety Engineering Lodz University of Technology, Wolczanska 213, 90-924 Lodz, Poland.
⁴ Faculty of Process and Environmental Engineering, Department of Bioprocess Engineering, Lodz University of Technology, Wolczanska 213, 90-924 Lodz, Poland. Electronic address: marta.gmurek@p.lodz.pl.
⁵ Faculty of Chemistry, Department of Environmental Technology, University of Gdansk, ul. Wita Stwosza 63, 80-308 Gdańsk, Poland.
⁶ CNC - Center for Neuroscience and Cell Biology and Department of Physics, Faculty of Sciences and Technology, University of Coimbra, Rua Larga, Coimbra P-3004-516, Portugal.

PMID: 28753508
DOI: 10.1016/j.scitotenv.2017.07.180

Abstract

Conventional wastewater treatments are inefficient for the removal of parabens. The aim of this study was finding a suitable solution using ozone and UVA irradiation combined with TiO₂ catalysts doped with different noble metals (Ag, Pt, Pd, Au). Photocatalytic ozonation required lower amounts of ozone for higher efficiency on the removal of parabens, chemical oxygen demand (COD) and total organic carbon (TOC). The best catalyst for the initial contaminants degradation was 0.5% Ag-TiO₂ leading to total parabens removal using 46mgO₃/L. Due to the relative low mineralization achieved, the toxicity of the treated solutions was still compared with the initial one over several species (Vibrio fischeri, Lepidium sativum and Corbicula fluminea). All the treatments applied led to a clear decrease on the toxicity compared with initial mixture of parabens. From an economical point of view, it was concluded that the presence of UVA irradiation increased the energy consumption compared with catalytic ozonation with these catalysts but it can decrease the time of reaction. From the by-products analysis, it was concluded that hydroxylation appears to be the most significant reaction pathway and the main responsible for parabens degradation.

Keywords: By-products analysis; Cost evaluation; Doped TiO(2); Parabens degradation; Photocatalytic ozonation; Toxicity.