Investigation of CO(2) Adsorption on Avocado Stone-Derived Activated Carbon Obtained through NaOH Treatment

Activated carbons were prepared from avocado stone through NaOH activation and subsequent carbonization. The following textural parameters were achieved: specific surface area: 817–1172 m(2)/g, total pore volume: 0.538–0.691 cm(3)/g, micropore volume 0.259–0.375 cm(3)/g. The well-developed microporosity resulted in a good CO(2) adsorption value of 5.9 mmol/g at a temperature of 0 °C and 1 bar and selectivity over nitrogen for flue gas simulation. The activated carbons were investigated using nitrogen sorption at −196 °C, CO(2) sorption, X-ray diffraction, and SEM. It was found that the adsorption data were more in line with the Sips model. The isosteric heat of adsorption for the best sorbent was calculated. It was found that the isosteric heat of adsorption changed in the range of 25 to 40 kJ/mol depending on the surface coverage. The novelty of the work is the production of highly microporous activated carbons from avocado stones with high CO(2) adsorption. Before now, the activation of avocado stones using NaOH had never been described.