Carbon-mediated Visible-light Clay-Fe2O3–graphene Oxide Catalytic Nanocomposites for the Removal of Steroid Estrogens from Water
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Date
2020-12
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Journal of Water Process Engineering
Abstract
Graphene oxide (GO). These nanocomposites were used for the removal of steroid estrogens (E1, E2, E3 and EE2)from water under visible-light. The use of these photocatalytic nanocomposites lead to complete oxidation of the steroid estrogens at >80 % even under simultaneous presence of all estrogens in water. Complete mineralization was obtained for these estrogens with the range of 58–73 %. The presence of Fe-oxide in the nanocompositesincreased the photocatalytic efficiency but addition of GO further improved the photocatalytic efficiency. Thisimproved efficiency was further doubled when the nanocomposites were prepared with a carbon source (caricapapaya seeds). The presence of carbon in the nanocomposite matrix was confirmed using X-ray Photoelectron Spectroscopy and Elemental Analysis. The main contributors to photocatalytic efficiency of the nanocomposites are superoxide radicals (· ) and holes (h+). Under competitive conditions, the catalysts are still active although the extent of estrogen oxidation is somewhat lower. Changes in the ionic strength did not significantly influence the efficiency of the photocatalyst. This signifies that adsorption only plays a minor role in estrogen removal from water. Toxicity tests show that the treated water is safe for human consumption and the most efficient nanocomposite can be recycled three times without any significant loss of performance. Overall, the nanocomposite shows high potential for the effective removal of a cocktail of estrogens in raw wastewater, tap and rain water, attaining contamination levels that are within WHO safe limits
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Keywords
Visible-light, Photocatalyst, Steroid estrogen, Wastewater treatment, Carbon, Grapheneoxide
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