Construction of effectively dispersible CoTiO3/kaolinite catalysts: Enhanced degradation of tetracycline hydrochloride over peroxymonosulfate activation

Abstract

Novel CoTiO3/kaolinite (CTO/Kaol) composites were synthesized using a two-step method, successfully integrating nanoparticles with natural minerals. Transmission electron microscopy and N2 adsorption–desorption isotherms indicated that the CTO particles were uniformly dispersed across the kaolinite substrate, exhibiting a substantial specific surface area and porosity conducive to persulfate adsorption and activation. Remarkably, the CTO/Kaol30%/peroxymonosulfate (PMS) system demonstrated superior catalytic efficiency for tetracycline hydrochloride (TCH) degradation compared to pristine CTO and kaolinite, achieving 91.2% decomposition within 20 min and maintaining high efficiency across a pH range of 4–11. Probing via electron paramagnetic resonance (EPR), reactive oxygen species (ROS) quenching, and electrochemical analyses corroborated synergistic interactions within the radical/non-radical pathways—crucial for pollutant abatement. Singlet oxygen (1O2) emerged as the principal reactive species propelling degradation, while sulfate radicals (SO4•−) played a complementary role. Beyond TCH, the CTO/Kaol30% composite exhibited potent degradation and mineralization capabilities for diverse antibiotics, including sulfamethoxazole, chlortetracycline, and ciprofloxacin. This investigation provides insight into the design of high-performance kaolinite-based catalytic systems, fostering the broader application of Fenton-like processes in the remediation of antibiotic-laden aqueous environments.