Effect of one-step and two-step H3PO4 activation on activated carbon characteristics

The objective of this study was to investigate the effect of one-step and two-step H3PO4 activation on activated carbon characteristics. Kanlow Switchgrass and Public Miscanthus and their biochars obtained via pyrolysis were used as precursors. The precursors were impregnated with H3PO4 and activated at a temperature of 900°C to produce biomass-derived and biochar-derived activated carbons. The activated carbons were characterized for textural characteristics, surface chemistry and microstructure. The activated carbons were also tested for their adsorption capacities for caffeine and acetaminophen. The biomass-derived activated carbons (KSBM and PMBM) had the highest BET surface areas of 1373 and 999 m2/g, respectively. The total pore volumes of the biomass-derived activated carbons were about two-fold higher than the biochar-derived activated carbons. In addition, the monolayer adsorption capacities of the biomass-derived activated carbons were about five folds higher than that of biochar-derived activated carbons for the adsorption of caffeine and acetaminophen.