Solar-active clay-TiO2 nanocomposites prepared via biomass assisted synthesis: Efficient removal of ampicillin, sulfamethoxazole and artemether from water

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 degrees C (TZPP(5)). The presence of both biomass and TiO2 is essential for the effective function of the photocatalytic nanocomposites. With TZPP(5), 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 TZPP(5), 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 (approximate to 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 approximate to 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.