Photodegradation of ethyl paraben using simulated solar radiation and Ag3PO4 photocatalyst

Zacharias Frontistis; Maria Antonopoulou; Athanasia Petala; Danae Venieri; Ioannis Konstantinou; Dimitris I Kondarides; Dionissios Mantzavinos

doi:10.1016/j.jhazmat.2016.04.017

Photodegradation of ethyl paraben using simulated solar radiation and Ag₃PO₄ photocatalyst

J Hazard Mater. 2017 Feb 5;323(Pt A):478-488. doi: 10.1016/j.jhazmat.2016.04.017. Epub 2016 Apr 14.

Authors

Zacharias Frontistis¹, Maria Antonopoulou², Athanasia Petala¹, Danae Venieri³, Ioannis Konstantinou⁴, Dimitris I Kondarides¹, Dionissios Mantzavinos⁵

Affiliations

¹ Department of Chemical Engineering, University of Patras, Caratheodory 1, University Campus, GR-26504 Patras, Greece.
² Department of Environmental & Natural Resources Management, University of Patras, 2 Seferi St., GR-30100 Agrinio, Greece.
³ School of Environmental Engineering, Technical University of Crete, Polytechneioupolis, GR-73100 Chania, Greece.
⁴ Department of Environmental & Natural Resources Management, University of Patras, 2 Seferi St., GR-30100 Agrinio, Greece; Department of Chemistry, University of Ioannina, GR-45110 Ioannina, Greece.
⁵ Department of Chemical Engineering, University of Patras, Caratheodory 1, University Campus, GR-26504 Patras, Greece. Electronic address: mantzavinos@chemeng.upatras.gr.

PMID: 27106519
DOI: 10.1016/j.jhazmat.2016.04.017

Abstract

In this work, the solar light-induced photocatalytic degradation of ethyl paraben (EP), a representative of the parabens family, was studied using silver orthophosphate, a relatively new photocatalytic material. The catalyst was synthesized by a precipitation method and had a primary crystallite size of ca 70nm, specific surface area of 1.4m²/g and a bandgap of 2.4eV. A factorial design methodology was implemented to evaluate the importance of EP concentration (500-1500μg/L), catalyst concentration (100-500mg/L), reaction time (4-30min), water matrix (pure water or 10mg/L humic acid) and initial solution pH (3-9) on EP removal. All individual effects but solution pH were statistically significant and so were the second-order interactions of EP concentration with reaction time or catalyst concentration. The water matrix effect was negative (all other effects were positive) signifying the role of humic acid as scavenger of the oxidant species. Liquid chromatography-time of flight mass spectrometry revealed the formation of methyl paraben, 4-hydroxybenzoic acid, benzoic acid and phenol as primary transformation by-products; these are formed through dealkylation and decarboxylation reactions initiated primarily by the photogenerated holes. Estrogenicity assays showed that methyl paraben was more estrogenic than EP; however, parabens are slightly estrogenic compared to 17β-estradiol.

Keywords: Design of experiments; Endocrine disruptors; Reaction pathways; Visible light; Water.