Nanostructred catalysts for photo-oxidation of endocrine disrupting chemicals

Abstract

Removal of four Endocrine disrupting chemicals (EDCs) Estrone (E1), 17-β-estradiol (E2), Estriol (E3) and 17-α-ethynylestradiol (EE2) were investigated using UV oxidation and combined with Nafion/iron catalyst. Immobilization of iron on the perfluorosulfonic polymer, Nafion® has been investigated as a carrier for the oxidation of pollutants by hydroxyl radicals (heterogenous photo-Fenton mechanism). However, the low surface area of Nafion, less than 0.2 m2/g, usually results in low pollutant degradation rates. Sol-gel technology was used to produce a high surface area poly(dimethylsiloxane) (PDMS) modified Nafion/silica composite suitable for catalysis of the photo-Fenton reaction without significant leaching of iron. The incorporation of Nafion into silica greatly increases the accessibility of Nafion/iron loaded active site. PDMS reinforces the structure of silica and maintains the transparency of the composite, which is essential for efficient Photo-Fenton reactions. These composites were utilized for the decomposition of estrogens which are Estrone (E1), 17-β-estradiol (E2), Estriol (E3) and 17-α-ethynylestradiol (EE2). In consequence, it is clear that the composite effectively catalyses the photo-Fenton reaction to remove estrone. The presence of iron through the use of the catalyst leads to rapid degradation of the estrone compared to just H2O2 and UV light alone. It was found that the addition of only 8.5 mg/L H2O2 produced more than conversion of estrogens within 60 min.