Sustainable nanoporous carbon for CO2, CH4, N2, H2 adsorption and CO2/CH4 and CO2/N2 separation

The huge production of waste agricultural and biomass products has a negative impact on the environment, thus necessitating economic and environmental recycling of abundant bio-waste materials to useful materials. To recycle and convert bio-waste materials, a sustainable nanoporous carbon from bio-waste (peanut shell, gingko, and metasequoia leaves) is facilely synthesized via one-step carbonization. Carbonized samples contain a small quantity of metal and non-metal residues (including sulfur and phosphorus), resulting in naturally doped porous carbon. The porosity, morphology, and composition of the nanoporous carbons were investigated and compared with those of commercially available activated carbon. Pure component adsorption isotherms of CO2, CH4, and N2 were also measured at 40 °C up to1 bar for all samples. These data were used to estimate the separation selectivity for CO2/CH4 and CO2/N2 1:1 binary mixtures and pressures according to the ideal adsorbed solution theory (IAST) model. Carbonized gingko leaf had the lowest SSA and pore volume but the highest S and P contents, with the highest average selectivity of 506 and 54 for CO2/N2 and CO2/CH4, respectively. This implies that the composition of the prepared carbon materials plays a significant role in their CO2 adsorption and separation ability, rather than their textural properties.