Enhanced SO2, NO, and Cr (VI) removal by lignin-derived high N-doped activated carbon through one-pot strategy: Structure development, structure–performance relationship and mechanism insight

The production of high-performance activated carbon (AC) is recognized as an essential strategy for the effective utilization of lignin resources. In this work, the N-doped AC was successfully prepared by blending sodium lignosulfonate (SL) and different ratios of FeCl 3 through one-pot strategy. The AC structure evolution and performance were obtained by a series of characterization and tests. The results showed that, during the activation process, FeCl 3 first complexed with urea and catalyzed the depolymerization of SL, and the rapid pore development was mainly caused by the template, including formed FeCl 2 , Na 2 Fe 3 Cl 8 and Na 6 FeCl 8 . The ratio of FeCl 3 /SL adjusts the AC physicochemical texture. AC-3 processed a super total specific surface area and pore volume, respectively up to 2048 m 2 /g and 1.47 cm 3 /g. Meanwhile, AC-2 showed a higher nitrogen content of 11.4 %. The as-prepared AC shows super desulfurization, denitrification and Cr (Ⅵ) removal ability. AC-2 displayed maximum sulfur capacity and NO conversion, up to 199.1 mg/g and 42.4 %. This enhanced performance is primarily attributed to the pore structure induced by FeCl 3 activation, which provides a foundation for adsorption and catalytic processes, further augmented by the increased active sites due to nitrogen doping. AC-3 achieved an extremely high Cr (VI) adsorption capacity, up to 386.2 mg/g, which was primarily attributed to the redox effect of N-containing and O-containing groups on Cr (VI), in addition, the effect of physical adsorption including pore structure is not neglectable. This study highlights the significant potential of environmentally friendly lignin-based porous carbon materials for removing contaminants in both gas and liquid phases.