A novel method to greener carbon material for CO2 adsorption

Abstract

This study explores the chemical activation using K2CO3 and Fe(NO3)3 to alter the porous structure and a novel nitrogen functionalisation biomass derived carbon using cold plasma. The results showed that the obtained walnut shell carbon demonstrated a remarkable CO2 adsorption capacity of 5.69 mmol g−1 at 0°C, 1 bar and 3.94 mmol g−1 at 25°C, 1 bar. Further assessment of adsorption capacities at high pressures (up to 4 bar) demonstrated the adsorption capacity of 8.03 mmol g−1 at 0°C, 4 bar and 6.33 mmol g−1 at 25°C, 4 bar. Cold plasma is a novel method to increase the nitrogen functional group content to 10.37 at%. This study showed that, however, surface nitrogen functional groups do not contribute to CO2 adsorption, and despite the presence of nitrogen groups, physisorption is the dominant factor controlling the CO2 adsorption of walnut shell derived carbon.