Solar-driven removal of selected organics with binary ZnO based nanomaterials from aquatic environment: Chemometric and toxicological assessments on wheat

This research aimed to investigate the removal efficiency of the pesticide clomazone, as well as two pharmaceutically active compounds, ciprofloxacin and 17 alpha-ethynilestradiol, using sustainable heterogeneous photocatalysis with newly synthesized binary coupled ZnO/MeOx nanopowders (ZnO/MgO, ZnO/CeO2, and ZnO/ZrO2) as photocatalysts, under various experimental conditions (catalyst loading and initial pH). The newly synthesized nanomaterials were characterized using XRD, SEM-EDS, TEM, DLS, Raman and UV/Vis spectroscopy, and zeta potential. The XRD proved the nanocrystalline size of the synthesized photocatalysts in the range 40-17 nm. The difference in morphology (shape and size) was determined and all elements were quantified using SEM-EDS. TEM images confirmed the successful formation of ZnO/MeOx heterojunctions. DLS measurements showed distributions with mean hydrodynamic particle diameters of 1226, 1042, and 944 nm for ZnO/MgO, ZnO/CeO2, and ZnO/ZrO2 powders, respectively. Raman also proved the successful preparation of binary nanomaterials. Considering the UV/Vis spectroscopy results, bandgap energy was found to be in the range 3.241-3.249 eV. BET analysis was used to determine specific surface area, 13.6852, 11.0554, and 8.5519 m(2)/g for ZnO/MgO, ZnO/CeO2, and ZnO/ZrO2. Optimal photocatalytic experimental conditions were defined using chemometrics. Chemical oxygen demand and ion chromatography analyses additionally confirmed the successful pollutant removal. The mechanism of CIP photocatalytic degradation and photocatalyst reutilization study were conducted under optimal conditions. After two consecutive runs, the reutilization study revealed that there was no loss of photocatalytic efficiency, while the contribution of various reactive species was: h(+) > (OHads)-O-center dot > (OHfree)-O-center dot. And finally, the toxicity of mixtures was observed on wheat samples.