Facile construction of a cobalt-incorporated N-doped porous carbon from biomass for highly efficient removal of tetracycline

The performance of heterogeneous carbon-based catalysts in advanced oxidation processes (AOPs) significantly relies on their structure and surface active sites. Herein, the cobalt-incorporated N-doped porous carbon (Co-NC) was successfully prepared from tannin by utilizing its strong ability to coordinate with metal ions. The characterization results revealed that Co-NC-900 possessed a porous structure with abundant mesopores, a relatively large BET surface area (187.16 m2/g), multivalent cobalt species (Co0, Co2+, Co3+) and optimal surface nitrogen sites. As a result, Co-NC-900 demonstrated efficient PMS activation, resulting in a 97.4% removal of tetracycline (TC), along with a rate constant (kobs) of 0.131min-1 and TOC removal efficiency of 55.3% within 30min. The analysis of radical inhibition and EPR results revealed that TC degradation was attributed to both non-radical (1O2) and radical (•OH and SO4•-) pathways. In addition, the outperformance of Co-NC-900 compared to Co-C-900 and NC-900 highlights the essential contributions of both Co and N in PMS activation. Mechanism studies have revealed that the presence of multivalent Co species promotes the Co-based redox cycle. This, in association with the enhanced electron transfer efficiency facilitated by N doping sites, accelerates the rapid generation of reactive oxygen species (ROSs). This work provides a straightforward strategy to fabricate transition metal-incorporated N-doped porous carbon catalysts from eco-friendly biomass, contributing to the effective treatment of organic contaminant.