Activated carbons from molasses as CO₂ sorbents

Aim of this research is to obtain effective, molasses based activated carbon, which would adsorb big amounts of CO₂. Molasses was mixed with KOH. Weight ratio of dry materials was 1:1 (AC1, AC3) and 1:2 (only AC2). Homogeneous mixture was obtained. Material was left for 3 h at 25°C. Drying lasted for 12 h at 200°C, and the material was grounded. The mixture was pyrolysed at 750°C, under constant flow (18 dm³/min) of nitrogen. The material was grounded again. Then, powder was washed with water, until filtrate was neutral, which took about 5 dm³ of water. AC3 was washed with 1 dm³ of water. After drying, materials were soaked in HCl (0.1 mol/dm³) for 19 h, and washed with water, until filtrate was neutral. CO₂ adsorption was performed under high pressure up to 40 atm, at 40°C. Specific surface area (according to the Brunauer-Emmett-Teller equation) was calculated for AC1, AC2 and AC3 and it is respectively 1985, 1967, and 2026 m²/g, micropore volume - 0.714, 0.707, and 0.728 cm³/g and it was between 75% and 89% of total pore volume. The excess uptake at 40 atm pressure was as follows: AC1 - 14.02 mmol/g, AC2 - 12.75 mmol/g, and AC3 - 15.79 mmol/g.