Manipulating High-Valent Cobalt-Oxo Generation on Co/N Codoped Carbon Beads via PMS Activation for Micropollutants Degradation
Junjun Pei, Kaixing Fu, Yukui Fu, Xiaolong Liu, Shenglian Luo, Kai Yin, Jinming Luo
Abstract
Manipulating high-valent cobalt-oxo [Co(IV)═O] species in a catalytic system is pivotal; however, it is challenging due to the inefficiency and unsustainability of Co(IV)═O generation. In this study, we fabricated macroscopic porous Co/N codoped carbon beads (Co–NC) and identified Co(IV)═O as the prominent species in peroxymonosulfate (PMS) activation. Specifically, Co(IV)═O species on a Co–NC-900/PMS system was regarded as the crucial driver of tetracycline (TC) removal (with a degradation efficiency of 97.3% and an initial concentration of 20 mg L –1 ) through quenching experiments, methyl phenyl sulfoxide (PMSO) degradation, and methyl phenyl sulfone (PMSO 2 ) generation. Importantly, Co–N x active sites are responsible for the formation of Co(IV)═O species, which contribute as much as 98.33% to TC degradation based on the calculation of the steady-state concentration. In addition, the relative contributions of Co(IV)═O toward various micropollutants are substrate-specific and related to their ionization potential (IP). The practical application of Co–NC-900 was further evaluated in the continuous flow mode, and it showed excellent durability and performance. Overall, we have aroused the importance of Co(IV)═O on micropollutants removal in heterogeneous systems and provided an alternative macroscopic catalyst that can be potentially exploited in real water decontamination scenarios.