Soda lignin-based activated carbon and its adsorption properties

Soda lignin-based activated carbons (AC) were successfully prepared through chemical curing with hexamethylenetetramine (HMTA), followed by carbonization and steam activation. The pore structure, surface chemical structure, and adsorption properties of the ACs were investigated. The obtained ACs exhibited a high specific surface area (SBET) and total pore volume (Vtotal), which first increased and then decreased with an increasing HMTA concentration. The highest values were approximately 1800 m2/g and 1.0 mL/g, respectively. The SBET and Vtotal were comparable or superior to those of ACs prepared with various activation methods reported in the literature. By increasing the HMTA concentration, the amount of graphitic carbon, which was the main compound on the surface of the ACs, decreased and then slightly increased, while the functional groups containing C-O showed the opposite tendency. Additionally, the great adsorption capacities of the ACs for methylene blue and iodine were mainly related to the carbonyl group chemical structure and pore structure.