Mineral-derived layered carbon-based catalysts for enhanced Fenton-like reactions and catalytic ceramic membrane systems: Si-O coordination mediates radical generation and electron transfer

Taking advantage of the silica-rich layered structure of montmorillonite (MT), carbon-based catalysts are expected to efficiently activate peroxymonosulfate (PMS), avoiding the instability and metal leaching problems of metal catalysts. This study developed innovative metal-free catalysts (10 N/C@Si) with Si-O coordination derived from the naturally abundant MT, which was different from the conventional methods of using them as carriers or ion doping. The fabricated 10 N/C@Si catalysts with a large specific surface (368.7 m2/g) area exhibited a significant catalytic oxidation ability for tetracycline (kobs = 0.401 min -1). The degradation mechanism included enhanced radical and electron transfer. The Si-O coordination can lead to the cleavage of adsorbed PMS, accelerating the generation of radicals, and can also serve as a bridge for the transfer of electrons from tetracycline to the 10 N/C@Si/PMS complexes, as proved by density-functional theory (DFT) computations. Additionally, loading of 10 N/C@Si on ceramic membranes (CM) achieved an extraordinarily large water flux of 505.0 L·m−2·h−1 and showed full oxidation of tetracycline, which simultaneously allowed efficient in-situ degradation and one-step solid–liquid separation.