The objective of this study was to investigate the adsorption characteristics of activated carbons (AC) synthesized from herbaceous biomass following two activation methods (1. Biomass+activation agent-&gt; activated carbon and 2. Biomass-&gt; bio-char+activation agent-&gt; activated carbon). The precursors for the activated carbon synthesis were biomass and biochar derived from it. The precursors were impregnated with phosphoric acid and thereafter activated at a temperature of 900 °C in inert condition. The surface morphology, porosity and surface chemistry of the activated carbons were characterized. Also, the activated carbons were used in adsorbing two pharmaceutical active compounds; acetaminophen and caffeine. Activated carbons synthesized directly from the biomass had high surface area (2459 m<sup>2</sup>/g) while the biochar derived AC had low surface area (1024 m<sup>2</sup>/g). The adsorption experimental data were fitted into Langmuir and Freundlich isotherm models. The Langmuir isotherm was found to provide the best fit for the equilibrium adsorption for the biomass derived AC, which had maximum monolayer adsorption capacities of 102.04 mg/g and 129.9 mg/g for caffeine and acetaminophen, respectively. On other hand, the maximum monolayer adsorption capacities for the biochar derived AC were 20.16 mg/g and 49.02 mg/g for caffeine and acetaminophen, respectively. The pseudo-second order model was found to be the best fit for the adsorption kinetics of the activated carbons. The half-life time required for the adsorbent to uptake half of the adsorbate amount at equilibrium was found to be 21.41 min and 6.50 min for biomass derived AC and biochar derived AC, respectively for the adsorption of caffeine. The half-life time for acetaminophen were found to be 8.99 min and 47 min for biomass derived AC and biochar derived AC, respectively. The initial adsorption rates for caffeine and acetaminophen were 3.35 mg/g/min and 0.92 mg/g/min, respectively for the biochar derived AC. The initial adsorption rates for the biomass derived AC were 6.58mg/g/min and 9.59 mg/g/min for caffeine and acetaminophen, respectively. The study showed that the impregnation of the activation agent directly into the biomass precursor produced a better activated carbon than impregnating biochar derived from biomass.

Adsorption of pharmaceutical active compounds using activated carbons synthesized from herbaceous biomass

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.