Characterization and analysis of activated carbons prepared from furfural residues by microwave-assisted pyrolysis and activation

Activated carbons (ACs) were prepared from furfural residues (FRs) by microwave-assisted pyrolysis and activation under CO 2 atmosphere in this study. At microwave activation temperature of 800 °C and activation time of 20 min, KOH impregnated ACs (MKFRAC*) reached the maximum adsorption ability. While water-washed FRs (MWFRAC*) needed higher processing temperature and longer treatment time (850 °C/60 min) to attain its maximum adsorption capacity . Raman showed MKFRAC* had a high R-value, indicating the graphite structure's low crystallinity caused by the porous structure . The iodine adsorption value, Methylene Blue (MB) number, and yield of MKFRAC* were 1159.1 mg/g, 448.0 mg/g and 26.8% wt%, respectively. The mesopore volume of MKFRAC* was >48%, more than those of other ACs mainly due to the synergistic effect of chemical reagents , carbon structure and microwave irradiation . The investigation on the adsorption mechanism of MB on ACs revealed that MB adsorption capacities of MKFRAC were well described by the Langmuir model, showing a maximum monolayer adsorption capacity of 562.9 mg/g, while MB adsorption kinetics of MKFRAC followed a pseudo-second-order model. The results showed microwave preparation of FR-based ACs was a feasible technique with potential industrial applications.