Influences of aggregation behavior of lignin on the microstructure and adsorptive properties of lignin-derived porous carbons by potassium compound activation

[Display omitted] •Technical lignin derived from different process has different structure and microstructure.•Aggregation behavior of lignin had great effect on carbonization and activation.•KHCO3 had the best activation effect for AL with a highly aggregated microstructure.•KOH had the best activation effect for LS with a highly dispersed microstructure.•Lignin-derived porous carbon has excellent adsorption properties for sulfamethazine. In this work, lignin-derived porous carbon was prepared using alkali lignin (AL) or lignosulfonic acid (LS) as a precursor to reveal the activation effects of potassium compound (KHCO3, K2CO3 and KOH) on technical lignin with different degree of aggregation. Quartz crystal microbalance with dissipation and atomic force microscope testing results showed that KHCO3 had the best activation effect on AL having a highly aggregated and dense microstructure, thanks to the expansion effect from KHCO3. LS has a highly dispersed and loose microstructure, and KOH had the best activation effect on LS. This is because the stabilizing effect from KOH could avoid excessive destruction of pore structure during carbonization and activation process. Therefore, the specific surface area of AL-derived porous carbon obtained with KHCO3 and LS-derived porous carbon obtained with KOH could reach 2084 and 2770m2g−1, while the absorption capacity could reach 701 and 870mgg−1 for sulfamethazine respectively. Our result provides a theoretical base for preparing high quality lignin-derived porous carbon adsorbent with different kinds of technical lignin.