Large-Scale Preparation of Granular Sludge@MOF-Derived Hierarchical Porous Carbon Catalysts for Advanced Oxidation Process: Preparation Process and Intrinsic Degradation Mechanism

Tetracycline (TTCH) is widely used but difficult to remove, which poses a threat to the health of the ecosystem, so it is urgent to take effective measures to remove it. Granular sludge plays an important role in biochemical treatment. Its rich functional groups and loose porous structure make it a potential catalyst carrier. This study utilized granular sludge as a precursor and modified it by loading a Zn/Co-zeolite imidazolate framework (ZIF-67/8). After carbonization, a granular sludge-supported MOF-derived porous carbon material (GSZC-800) with high catalytic activity is produced. The degradation rate of tetracycline reached a maximum of 90.8% after 40 min of reaction, and the optimal conditions were 20 ppm of initial pollutant concentration, 0.05 g/L of catalyst, and 0.10 g/L of peroxymonosulfate (PMS), which is superior to biomass-charcoal derived catalysts that have been reported in the literature. Through ion interference experiments, radical quenching experiments, electron transfer mechanism studies, and fluorescence spectroscopy analysis, it is suggested that this is a non-radical mechanism dominated by a single linear oxygen species. The catalyst GSZC-800 exhibits an ease of preparation and accessibility, has a wide range of applicable pH values, and effectively removes different pollutants. It has potential applications in treating actual wastewater and various pollutants. This study not only provides a new idea for the high-value utilization of granular sludge, but also provides an important theoretical and experimental basis for the development of efficient and stable non-homogeneous catalysts.