Modulation of C=O groups concentration in carbon-based materials to enhance peroxymonosulfate activation towards degradation of organic contaminant: Mechanism of the non-radical oxidation pathway

Current research has found that C=O groups hold a significant position in the oxidation process of peroxymonosulfate (PMS) in the activated carbon system, influencing both the generation of reactive species and the degradation of organic contaminants. Quinone organic compounds, which are rich in C=O groups, exhibit high reactivity but also inherent toxicity. Additionally, these compounds decompose easily at high temperatures, complicating their use in carbon-based materials. This study introduces a novel approach to enhance the content of C=O groups in carbon materials by controlling the synthesis of sulfur heterocyclic organic quinone (SHQ) precursors. For the first time, we established a sulfur heterocyclic organic quinone-derived carbon (SHQC)/PMS system, where SHQC catalysts demonstrate remarkable catalytic efficiency in activating PMS for the degradation of organic pollutants. In different natural water matrices, the removal rate of tetracycline hydrochloride (TC) exceeds 90 % under optimized conditions (SHQC-9: 0.2 g L −1 , PMS: 1 mM, TC: 4.45 mg L −1 ). The C=O group was identified as the active site for PMS activation through a combination of quantitative structure-activity relationships, specific site blocking, and antithesis methods. The activation mechanism was elucidated through scavenger experiments and electron paramagnetic resonance (EPR) analysis. The results indicate that the superior catalytic performance of the SHQC-9/PMS system is due to a non-radical pathway, with singlet oxygen ( 1 O 2 ) being the primary species responsible for TC degradation. These findings offer a novel pathway for designing highly efficient, safe, and environmentally friendly carbon material catalysts.