Harnessing the radical potential of calcium-activated biochar for non-peroxide catalytic degradation of bisphenol S

Biochar, characterized by its rich surface functional groups, defective structure, and inherent aromaticity, serves as a promising catalyst in Advanced Oxidation Processes (AOPs). The generation of Reactive Oxygen Species (ROS) stems from the heterolytic cleavage of peroxides, facilitated by electron transfer from biochar's functional groups. However, safety hazards of peroxides during transportation and storage persist. This study explores a non-peroxide-based oxidation mechanism via Calcium Chloride-activated biochar (CaBC). Remarkably, upon aeration, Bisphenol S (BPS) concentration in water decreased by 25.7 % after reaching adsorption saturation. Reactive Oxygen Species (ROS) generation was confirmed by electron paramagnetic resonance, with species including center dot OH, center dot O2-, center dot CH3, center dot CH2OH, and CH3C(=O)OO center dot. Degradation products of BPS were identified using Liquid Chromatography-Mass Spectrometry (LC-MS), their biosafety was assessed, and the degradation pathways of BPS were analyzed through density functional theory (DFT) calculations. This study highlights the potential of biochar in safer, mild catalytic oxidation processes and offers insights into the radical reactions of carbon-based materials in aqueous environments.

Automated summary

Biochar, with its rich surface functional groups, defective structure, and inherent aromaticity, shows promise as a catalyst in Advanced Oxidation Processes (AOPs). This study explores a non-peroxide-based oxidation mechanism using Calcium Chloride-activated biochar (CaBC), and identifies the reactive oxygen species (ROS) generated and the degradation pathways of BPS. The study highlights the potential of biochar in safer, mild catalytic oxidation processes and offers insights into the radical reactions of carbon-based materials in aqueous environments.