title: Photodegradation of estrogenic endocrine disrupting steroidal hormones in aqueous systems: Progress and future challenges.
abstract: This article reviews different photodegradation technologies used for the removal of four endocrine disrupting chemicals (EDCs): estrone (E1), 17β-estradiol (E2), estriol (E3) and 17α-ethinylestradiol (EE2). The degradation efficiency is greater under UV than visible light; and increases with light intensity up to when mass transfer becomes the rate limiting step. Substantial rates are observed in the environmentally relevant range of pH7-8, though higher rates are obtained for pH above the pKa (~10.4) of the EDCs. The effects of dissolved organic matter (DOM) on EDC photodegradation are complex with both positive and negative impacts being reported. TiO2 remains the best catalyst due to its superior activity, chemical and photo stability, cheap commercial availability, capacity to function at ambient conditions and low toxicity. The optimum TiO2 loading is 0.05-1gl(-1), while higher loadings have negative impact on EDC removal. The suspended catalysts prove to be more efficient in photocatalysis compared to the immobilised catalysts, while the latter are considered more suitable for commercial scale applications. Photodegradation mostly follows 1st or pseudo 1st order kinetics. Photodegradation typically eradicates or moderates estrogenic activity, though some intermediates are found to exhibit higher estrogenicity than the parent EDCs; the persistence of estrogenic activity is mainly attributed to the presence of the phenolic moiety in intermediates.
authors.affiliation: School of Civil and Environmental Engineering, University of Technology Sydney, NSW 2007, Australia.
authors.forename: Kireesan
authors.initials: K
authors.lastname: Sornalingam
authors.affiliation: School of Mathematical and Physical Sciences, Faculty of Science, University of Technology Sydney, NSW 2007, Australia.
authors.forename: Andrew
authors.initials: A
authors.lastname: McDonagh
authors.affiliation: School of Civil and Environmental Engineering, University of Technology Sydney, NSW 2007, Australia. Electronic address: junliang.zhou@uts.edu.au.
authors.forename: John L
authors.initials: JL
authors.lastname: Zhou
mesh_terms: D052244:Endocrine Disruptors / Q000032:analysis / Q000737:chemistry*; D004964:Estriol / Q000032:analysis / Q000737:chemistry; D004967:Estrogens / Q000032:analysis / Q000737:chemistry; D004970:Estrone / Q000032:analysis / Q000737:chemistry; D004997:Ethinyl Estradiol / Q000032:analysis / Q000737:chemistry; D007700:Kinetics; D010782:Photolysis; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*
chemical_list: D052244:Endocrine Disruptors; D004967:Estrogens; D014874:Water Pollutants, Chemical; D004970:Estrone; D004997:Ethinyl Estradiol; D004964:Estriol
keywords: Advanced oxidation process; Endocrine disrupting chemicals; Estrogenic activity; Photodegradation pathways; Titanium dioxide