Solar-active clay-TiO2 Nanocomposites Prepared via Biomass Assisted Synthesis: Efficient Removal of Ampicillin, Sulfamethoxazole and Artemether from Water
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Date
2020-07
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Chemical Engineering Journal, Elsevier
Abstract
New solar-active nanocomposites free from toxic reagents or precious metals were developed. They were prepared from natural kaolinite clay, Na2WO4, titania, and biomass. The photocatalytic activity of the nanocomposites against two antibiotics [Ampicillin (AMP) and Sulfamethoxazole (SMX)] and an antimalarial drug [Artemether (ART)] under sunlight suggests an unusually fast photodegradation that is > 90% complete in
30 min especially with the photocatalytic nanocomposite prepared from Musa paradisiaca peels (plantain peels) @ 500 °C (TZPP5). The presence of both biomass and TiO2 is essential for the effective function of the photocatalytic nanocomposites. With TZPP5, ca. 80% and ca. 50% mineralisation of AMP and SMX, respectively, was observed after 60 min. The photocatalytic reaction releases inorganic by-products (SO42−, NO3− and NH4+) at levels below WHO permissible limits for drinking water. The presence of anions reduces the efficiency of TZPP5, indicating that it releases electrons and reactive oxygen species that are also responsible for photodegradation of
the drugs. However, changing concentrations of electrolyte (NaCl) do not influence its efficiency, suggesting that
adsorption may not precede photocatalysis, contrary to common models. Reuse studies suggest a slight loss in
photodegradation efficiency (≈6%) of the nanocomposite for AMP in the first two cycles followed by subsequent
stability at 70% for subsequent cycles. This is different for SMX, which maintained ≈58% removal for all cycles
after the 1st cycle. With efficient treatment of raw wastewater from an abattoir, a river, and a hand-dug well for
drinking water, the photocatalytic nanocomposite shows potential for treating drinking water, especially in
point-of-use water treatment devices.
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