Construction of a novel ZnBi2O4/ZIF-67 S-scheme heterojunction for enhanced photocatalytic performance in tetracycline hydrochloride degradation through peroxymonosulfate activation

ZnBi₂O₄/ZIF-67 S-scheme heterojunction (ZBO/ZIF-67) was successfully synthesized through a solvent-induced process at room temperature for the effective degradation of tetracycline hydrochloride (TC-HCl). The catalysts were characterized by XRD, FTIR, XPS, FE-SEM, EDX, TEM, PL, UV-Vis DRS, TGA, EIS, and photocurrent response analyses. Scavenger tests were used to investigate the photocatalytic reaction mechanism under visible light. The photocurrent response was utilized to confirm the enhanced photocatalytic performance in the heterojunction. In antibiotic degradation, the effective use of photocatalytic processes with peroxymonosulfate (PMS) is attributed to the enhanced production of reactive oxygen species (ROS). The ZBO/ZIF-67/PMS system demonstrated greater degradation capacity compared to the ZBO/ZIF-67 system, with a reduce in reaction time, while ZIF-67 exhibited effectiveness in the Co²⁺/Co³⁺ cycle for activating PMS. The optimum operating parameters were obtained by the Central Composite Face-Centered method (CCF) as pH = 5, light intensity = 11.1 mW/cm², the ratio of photocatalyst load to the TC-HCl concentration = 10 mgCat/mgTC-HCl, and irradiation time = 90 min. The ZBO/ZIF-67/PMS system achieved 93.4 % TC-HCl degradation in just 15 min under visible light. After 90 min of photocatalytic reaction, the ZBO/ZIF-67 system achieved a TC-HCl removal efficiency of 90.4 %, while the ZBO/ZIF-67/PMS system reached 99.6 %. The influence of PMS concentration was examined, showing that 0.5 g/L is the optimal value. The leaching of metal ions, stability, and reuse potential of the ZBO/ZIF-67/PMS system were examined, and environmental safety was confirmed by the reduction in TC-HCl toxicity, demonstrated by OD₆₀₀ measurements of Escherichia coli (E. coli) and enhanced plant root growth. The results revealed that the catalyst displayed excellent activity over five cycles. This study provides new insights into PMS activation using the ZBO/ZIF-67 heterojunction, potentially expanding strategies for photocatalyst-based PMS activation in degrading antibiotic pollutants in water.