Surface modification of broom sorghum-based activated carbon via functionalization with triethylenetetramine and urea for CO2capture enhancement
Elaheh Mehrvarz , Ali A. Ghoreyshi , Mohsen Jahanshahi
Front. Chem. Sci. Eng. ›› 2017, Vol. 11 ›› Issue (2) : 252 -265.
Surface modification of broom sorghum-based activated carbon via functionalization with triethylenetetramine and urea for CO2capture enhancement
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 m2·g−1 and the highest micropore volume of 0.671 cm3·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−1which 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 CO2adsorption onto the ACs. The evaluation of the isosteric heat of adsorption demonstrated the exothermic nature of the CO2 adsorption onto unmodified and modified samples.
activated carbon / broom sorghum / functionalization / CO2 capture
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Higher Education Press and Springer-Verlag Berlin Heidelberg
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