Frontiers of Chemical Science and Engineering
>> 2017,
Volume 11,
Issue 2
doi:
10.1007/s11705-017-1630-6
RESEARCH ARTICLE
Surface modification of broom sorghum-based activated carbon via functionalization with triethylenetetramine and urea for CO
Chemical Engineering Department, Babol University of Technology, Shariati Av., Babol, Mazandaran 47148-71167, Iran
Accepted: 2017-03-29
Available online: 2017-05-12
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Abstract
A new type of activated carbon (AC) was synthesized using broom sorghum stalk as a low cost carbon source through chemical activation with H PO and KOH. The AC obtained by KOH had the largest BET surface area of 1619 m ·g and the highest micropore volume of 0.671 cm ·g . CO 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 CO 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 CO uptake at 298 K and 1 bar achieved by AC-TETA and AC-urea was 3.22 and 2.33 mmol·g which shows a 92% and 40% improvement compared to pristine AC (1.66 mmol·g ), 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 CO adsorption onto the ACs. The evaluation of the isosteric heat of adsorption demonstrated the exothermic nature of the CO adsorption onto unmodified and modified samples.
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