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

Abstract

Activated carbons (ACs) were prepared from furfural residues (FRs) by microwave-assisted pyrolysis and activation under CO2 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.