Redox-Active MnOx-Biochar synthesis for bisphenol a removal with simultaneous CO-Rich syngas generation via Mn-Catalyzed CO2-mediated biomass thermochemical treatment.

Adsorptive removal of aqueous organic pollutants is often limited by mass-transfer kinetics to the adsorbent surface. To address this constraint, integrated adsorption-oxidation processes have been widely explored as a strategic measure because they enable in situ degradation of adsorbent-bound organic pollutants, thereby regenerating active sites and prolonging removal performance. However, many such systems require energy inputs and chemical oxidants, which hinder practical implementation. Here, we evaluate MnOx-loaded corncob (CC) biochar produced under a CO2 atmosphere (MnCCB (CO2)) as a bifunctional adsorption-oxidation material for bisphenol A (BPA) removal. Physicochemical characterization showed that CO2-assisted fabrication yielded MnOx with a higher oxidation state in MnCCB (CO2) than that in the N2-derived analogue (MnCCB (N2)). MnCCB (CO2) exhibited increased micro-/mesopore volume and a higher specific surface area. Consistent with these structural advantages, MnCCB (CO2) achieved a BPA removal rate constant of 8.48 × 10-2 min-1, outperforming MnCCB (N2) and pristine CC biochars produced under either N2 or CO2. Beyond pollutant removal, Mn-catalyzed CO2 mediated thermochemical treatment also enhanced syngas formation during MnCCB (CO2) production. This improvement is attributed to selective catalytic reactions between bio-oil and CO2, during which CO2 is converted to CO in the presence of MnOx. Overall, this work demonstrates the potential of CO2-assisted thermochemical treatment for the simultaneous production of functional biochar and syngas.