Crosslinked hydrogel-derived carbons activated by trace amounts of aqueous potassium carbonate for carbon dioxide adsorption

A new method for green synthesis of activated carbon using chitosan-based hydrogel precursors is reported. Chitosan-based hydrogel materials are designed to absorb trace amounts of non-toxic and non-corrosive activating agent K2CO3 from dilute aqueous solution. The K2CO3 impregnated hydrogels are further freeze-dried and converted to activated carbons with tuneable pore structure by a single-step pyrolysis. Activated carbon with highest pore volume of 0.76 cm3/g and surface area of 2026 m2/g is obtained by using K2CO3 as low as 0.23 g per gram of chitosan hydrogel. It can adsorb maximum CO2 of 4.2 mmol/g at 25 °C and 1 bar. This study demonstrates that biopolymer hydrogels impregnated with trace amounts of K2CO3 are excellent precursor materials to design high surface area carbons for CO2 capture.