Nitrogen-Doped High-Surface-Area activated carbon: Innovative adsorbent for enhanced SO2 and benzene removal

In this paper, we investigated the properties of nitrogen-doped activated carbon produced via the co-activation of KSCN and KOH, using hydrothermal lignin as a precursor. The resulting activated carbon exhibited a high specific surface area of 3504 m2/g and contained 3.37 % nitrogen from KSCN, which enhanced its adsorption efficiency. The adsorption capacities for SO2 and benzene at 273 K were measured at 2260.68 mg/g and 1668.90 mg/g, respectively. Competitive adsorption experiments at 298 K showed that in the presence of SO2, the activated carbon maintained a high adsorption capacity for benzene at 1008.81 mg/g, while the adsorption capacity for SO2 decreased to only 12.31 mg/g, indicating a higher affinity for benzene. The selectivity coefficient, calculated using the Ideal Adsorbed Solution Theory (IAST), reached 44.76 at a benzene-to-SO2 ratio of 2:1. To gain deeper insights into the selective adsorption mechanism, Density Functional Theory (DFT) simulations were conducted. These simulations confirmed the experimental findings, indicating that benzene can be selectively adsorbed and effectively separated from SO2 flue gas.