Synergistic adsorption-catalytic mechanism of biochar-activated persulfates for remediation of groundwater organic contamination: A review

Groundwater contamination has garnered significant attention, prompting the exploration of innovative treatment methods. Persulfate-based advanced oxidation processes (PS-AOPs), notably effective in degrading organic pollutants, have been enhanced by biochar. In the biochar/PS pollutant degradation system, both solid-phase and liquid-phase reactions often coexist. Therefore, adsorption on the biochar surface significantly impacts the utilization of surface-active sites, the activation mode of PS by biochar, and the pollutant degradation pathway. This review therefore focuses on the relationship and influence between the adsorption of biochar and its catalysis of PS degradation of organic pollutants from the perspective of the physicochemical properties of biochar, the mechanism of activation of PS, and the relationship between adsorption and catalysis interactions. Special attention is given to the coupling and polymerization processes facilitated by biochar, which not only enable selective conversion of pollutants into value-added polymeric products but also contribute to reduced CO₂ emissions by avoiding complete mineralization, thereby reducing the use of oxidants, thereby alleviating disturbances to the underground environment while aligning with the principles of green and sustainable development. In addition, it elucidates the influencing factors of the adsorption-catalytic synergistic effects of biochar. The review concludes with a discussion on future research directions, aiming to optimize the synergistic adsorption-catalytic capabilities of biochar in environmental remediation.