摘要
A new type of activated carbon （AC） was synthesized using broom sorghum stalk as a low cost carbon source through chemical activation with H3PO4 and KOH. The AC obtained by KOH had the largest BET surface area of 1619 m^2·g^-1 and the highest micropore volume of 0.671 cm^3·g^-1. CO2 adsorption was enhanced by functionalizing the AC with two different amines： triethylenetetramine （TETA） and urea. The structure of the prepared ACs was characterized by Brunauer-Emmett-Teller method, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and acid-base Boehm titration analyses. The adsorption behavior of CO2 onto raw and amine-functionalized ACs was investigated in the temperature range of 288-308 K and pressures up to 25 bar. The amount of CO2 uptake at 298 K and 1 bar achieved by AC-TETA and AC-urea was 3.22 and 2.33 mmol·g^-1 which shows a 92% and 40% improvement compared to pristine AC （1.66 mmol·g^-1）, respectively. Among different model isotherms used to describe the adsorption equilibria, Sips isotherm presented a perfect fit in all cases. Gas adsorption kinetic study revealed a fast kinetics of CO2 adsorption onto the ACs. The evaluation of the isosteric heat of adsorption demonstrated the exothermic nature of the CO2 adsorption onto unmodified and modified samples.
A new type of activated carbon （AC） was synthesized using broom sorghum stalk as a low cost carbon source through chemical activation with H3PO4 and KOH. The AC obtained by KOH had the largest BET surface area of 1619 m^2·g^-1 and the highest micropore volume of 0.671 cm^3·g^-1. CO2 adsorption was enhanced by functionalizing the AC with two different amines： triethylenetetramine （TETA） and urea. The structure of the prepared ACs was characterized by Brunauer-Emmett-Teller method, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and acid-base Boehm titration analyses. The adsorption behavior of CO2 onto raw and amine-functionalized ACs was investigated in the temperature range of 288-308 K and pressures up to 25 bar. The amount of CO2 uptake at 298 K and 1 bar achieved by AC-TETA and AC-urea was 3.22 and 2.33 mmol·g^-1 which shows a 92% and 40% improvement compared to pristine AC （1.66 mmol·g^-1）, respectively. Among different model isotherms used to describe the adsorption equilibria, Sips isotherm presented a perfect fit in all cases. Gas adsorption kinetic study revealed a fast kinetics of CO2 adsorption onto the ACs. The evaluation of the isosteric heat of adsorption demonstrated the exothermic nature of the CO2 adsorption onto unmodified and modified samples.
