Photocatalytic Removal of Metronidazole Antibiotics from Water Using Novel Ag-N-SnO2 Nanohybrid Material.

In this study, we employed a straightforward synthetic approach using the sol-gel method to fabricate a novel photocatalyst, Ag and N co-doped SnO2 (Ag-N-SnO2). The synthesized photocatalysts underwent characterization through various techniques including XRD, FTIR, FESEM-EDS, TEM, UV-vis DRS, BET, and XPS. The UV-vis DRS results confirmed a reduction in the bandgap energy of Ag-N-SnO2, leading to enhanced absorption of visible light. Additionally, TEM data demonstrated a smaller particle size for Ag-N-SnO2, and BET analysis revealed a significant increase in surface area compared to SnO2.The efficiency of the Ag-N-SnO2 photocatalyst in degrading metronidazole (MNZ) under natural sunlight surpassed that of SnO2. Under optimal conditions (Ag-N-SnO2 concentration of 0.4 g/L, MNZ concentration of 10 mg/L, pH 9, and 120 min of operation), the highest MNZ photocatalytic removal reached 97.03%. The reaction kinetics followed pseudo-first-order kinetics with a rate constant of 0.026 min-1. Investigation into the mineralization of MNZ indicated a substantial decrease in total organic carbon (TOC) values, reaching around 56% in 3 h of sunlight exposure. To elucidate the photocatalytic degradation mechanism of MNZ with Ag-N-SnO2, a scavenger test was employed which revealed the dominant role of •O2-. The results demonstrated the reusability of Ag-N-SnO2 for up to four cycles, highlighting its cost-effectiveness and environmental friendliness as a photocatalyst.

Mineralization of Diazinon with nanosized-photocatalyst TiO2 in water under sunlight irradiation: optimization of degradation conditions and reaction pathway.

The photocatalytic degradation of Diazinon under sunlight irradiation is investigated by using the nanosized photocatalyst TiO2. Eight intermediates are detected during the degradation, and the reaction pathway is proposed on the base of their intermediates. The degradation parameters, concerning photocatalyst concentration, temperature, pH, sunlight intensity and irradiation time are optimized. Under the optimal conditions, the photocatalytic degradation of Diazinon can be completed within 60 min. The photodegradation is found to follow the pseudo-first-order kinetic law at a rate constant of 0.068 min-1. The activation energy is 14.7 kJ/mol. The formations of sulphate, phosphate, nitrate and ammonium ions during the degradation are observed. About 83% of the initial N is detected as ammonium and nitrate ions during 50 h of irradiation time.

Fabrication of Ag-doped ZnO by mechanochemical combustion method and their application into photocatalytic Famotidine degradation.

Ag/ZnO nanocomposites are successfully synthesized at different Ag contents through simple, effective, high yield and low-cost mechanochemical combustion technique, with the addition of silver acetate to zinc acetate and oxalic acid mixture. The synthesized materials are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron spectroscopy (SEM), BET surface area analysis, UV - visible diffuse reflectance spectroscopy (UV - DRS) and photoluminescence spectroscopy (PL). It is shown that the prepared nanocomposites are composed of metallic Ag0 and wurtzite ZnO. The photocatalytic performance of different composites is evaluated by the degradation of Famotidine (FMT) under UV irradiation. The results indicate it that the maximum photodegradation rate is obtained with 6 wt% metallic Ag-decorated ZnO, and it is 2.1 times better than that obtained with pure ZnO. The photocatalytic degradation of FMT with Ag/ZnO is affected by various parameters such as calcination temperature and time, doping concentrations and reusability. The Ag/ZnO demonstrates higher activity due to the reduction of electron - hole recombination and Ag0 metal catalyst. The possible photocatalytic degradation mechanism of FMT with Ag/ZnO is estimated from the scavenger test.