Meta-kaolinite/LaFeCoO3 microsphere catalyst for photocatalytic persulfate activation: Enhanced removal of tetracycline hydrochloride

In this study, modified intercalated kaolinite was uniformly anchored on the surface of monodisperse LaFe0.5Co0.5O3 microspheres through a two-step approach. The tetracycline hydrochloride (TCH) removal efficiency of the samples was evaluated under a combined visible light/peroxodisulfate (Vis/PS) system. The meta-kaolinite/LaFe0.5Co0.5O3 (MK/LFCO) composite afforded enhanced photocatalytic activation of PS because of the rapid electron transfer, increased number of surface reactive sites, and enhanced specific surface area and pore volume caused by LFCO and MK. Density functional theory calculations revealed that Co doping could alter the charge distribution and accelerate localized charge separation. Additionally, the photogenerated carriers could be captured by the O vacancies and Co/Fe active sites, facilitating the separation of photogenerated carrier separation and Fe-III/Fe-II interconversion. Based on electron paramagnetic resonance spectroscopy and radical quenching experiments indicated that SO4 center dot- was the key radical species under the Vis/PS system. This work comprehensively reveals the mechanism of MK/LFCO-catalyzed TCH degradation, while providing novel insights regarding kaolinite-based catalysts for wastewater treatment under Vis/PS systems.

Automated summary

In this study, modified intercalated kaolinite was anchored on the surface of LaFe0.5Co0.5O3 microspheres, resulting in improved photocatalytic activation and TCH removal efficiency under the Vis/PS system. Co doping was found to alter the charge distribution and accelerate charge separation, while photogenerated carriers were captured by O vacancies and Co/Fe active sites. SO4 center dot- was identified as the key radical species in the Vis/PS system. Overall, this study provides insights into the mechanism of MK/LFCO-catalyzed TCH degradation and highlights the potential of kaolinite-based catalysts for wastewater treatment under Vis/PS systems.