A novel hierarchical TiO2@S-AZMB/ZnTi-LDH Z-scheme photocatalyst for enhanced metronidazole degradation

A novel TiO 2 @S-AZMB/ZnTi-LDH (TS/LDH) Z-scheme photocatalyst, exhibiting exceptional photocatalytic activity and stability, was developed for the first time through hydrothermal synthesis to facilitate the removal of the metronidazole (MTZ) antibiotic contaminant from recycled spent alkaline Zn-Mn batteries (S-AZMB). The Z-scheme charge carrier transfer technique enhanced the oxidizing and reducing capabilities of TiO 2 and ZnTi-LDH. The morphological, optical, and structural features of the optimum TS/LDH photocatalytic composite were studied using different investigations. The enhancement of responsiveness to visible light and the effective separation of charge carriers in TS/LDH resulted in a peak photocatalytic elimination of MTZ at 94 % (k=0.0191 min -1 ). The impacts of four independent variables, initial MTZ concentration (20–50 ppm), photocatalyst loading (0.5–2.5 g/L), solution pH (4–10), and irradiation duration (30–180 min) were assessed using central composite design (CCD). The optimal values of the variables were determined by response surface methodology (RSM). The findings validated the adverse effects of reduced photocatalyst dose and irradiation duration, with elevated pollutant concentration and pH, on the effectiveness of MTZ photodegradation. The optimal operating values were obtained initial MTZ concentration of 20 mg/L, reaction time of 180 min, photocatalyst loading of 1.5 g/L, and initial pH of 4. The photocatalyst maintained over 86 % of its initial activity after five successive cycles, demonstrating the stability and dependability of the photocatalytic activity of the TS/LDH composite. This study not only broadens the research implications of recycling for reuse but also introduces a novel method to enhance highly efficient Z-scheme photocatalysts.