Boron regulates catalytic sites of biochar to enhance the formation of surface-confined complex for improved peroxydisulfate activation

Biochar has been developed to activate persulfate for wastewater treatment due to its carbon essence, easily-available and low-cost. Efficiently active sites and interfacial electron transfer are highly desired for peroxydisulfate (PDS) activation. In this study, boronic ester structure and defect degree of boron-doped biochar are confirmed as activate sites to improve PDS activation. The performance of pollutants degradation is proven to have structure-activity relationships with both activate sites. Moreover, boron-doped biochar exhibits higher stability and oxidation potential by forming the surface-confined complex, promoting electron transfer from pollutants to complex. The optimized boron-doped biochar has the advantages of adapting to a broad pH range (2.9-10.0), strong resistance to Cl- and organic matters, a low activation energy of 11.22 kJ mol-1, and achieving the decomposition of practical dyeing wastewater. Our work provides a promising approach to regulating the interfacial catalytic sites of biochar by doping heteroatom for PDS activation in practical wastewater treatment.