Activation of peroxodisulfate by boron-nitrogen co-modified biochar: Synergistic effects of adsorption sites and catalytic centers

Abstract

The peroxodisulfate-based advance oxidation technologies (PS-AOPs) mediated by heteroatom-modified biochar demonstrates significant potential for pollutant degradation. This study successfully synthesized nitrogen-boron co-modified biochar (NB-BC) catalysts via impregnation-calcination and employed them for electrocatalytically activated PS degradation tetracycline (TC). The synergistic mechanism of this catalyst during the reaction process was systematically investigated. Experimental results reveal that the NB-BC catalyst calcined at 600 °C (NB-BC 600) exhibited superior catalytic activity within the PS activation system, achieving a degradation rate of 91.2 % for TC (10 mg/L) within 60 min, with a reaction rate of 0.0443. Combing characterization and theoretical calculations indicated that the synergistic effect of nitrogen and boron dual sites optimized the surface charge distribution of the biochar, facilitated electron transfer between the catalyst and PS, and enhanced the adsorption affinity between the catalyst and pollutants. Specifically, graphitic N accelerated electron transfer within the system and promoted the cleavage of the O-O bond in PS by modulating the surface charge of the biochar. Meanwhile, -BCO₂ groups introduced positively charged centers, thereby promoting the electrostatic adsorption process between the catalyst and TC molecules. This study provides a novel theoretical foundation and methodological guidance for leveraging heteroatom-modified biochar to enhance PS activation processes.