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

CO 2 thermochemical treatment yielded MnO x -biochar and CO-rich syngas. • Micro- and mesopore development enhanced BPA adsorption by MnCCB (CO 2 ). • MnO x rich in Mn(IV) and Mn(III) promoted catalytic BPA oxidation. • Char gasification and oxygenate conversion increased yields of CO and H 2 . 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 MnO x -loaded corncob (CC) biochar produced under a CO 2 atmosphere (MnCCB (CO 2 )) as a bifunctional adsorption-oxidation material for bisphenol A (BPA) removal. Physicochemical characterization showed that CO 2 -assisted fabrication yielded MnO x with a higher oxidation state in MnCCB (CO 2 ) than that in the N 2 -derived analogue (MnCCB (N 2 )). MnCCB (CO 2 ) exhibited increased micro-/mesopore volume and a higher specific surface area. Consistent with these structural advantages, MnCCB (CO 2 ) achieved a BPA removal rate constant of 8.48 × 10 -2 min −1 , outperforming MnCCB (N 2 ) and pristine CC biochars produced under either N 2 or CO 2 . Beyond pollutant removal, Mn-catalyzed CO 2 mediated thermochemical treatment also enhanced syngas formation during MnCCB (CO 2 ) production. This improvement is attributed to selective catalytic reactions between bio-oil and CO 2 , during which CO 2 is converted to CO in the presence of MnO x . Overall, this work demonstrates the potential of CO 2 -assisted thermochemical treatment for the simultaneous production of functional biochar and syngas. Download: Download high-res image (121KB) Download: Download full-size image