Experimental study of CO<sub>2</sub> and N<sub>2</sub> adsorption on activated carbon
Hedi Jedli, Maha M. Almoneef, Mohamed Mbarek, Abdessalem Jbara, Khalifa Slimi
Abstract
Abstract The present study as designed to assess the CO 2 and N 2 adsorption isotherms on activated carbon (AC). The AC was characterized with SEM, XRD and N 2 isotherm. The CO 2 and the N 2 adsorption experiments on the AC are performed at 298, 308 and 328 K and modelled by Langmuir model. The preferred selectivity ( α CO2/N2 ) was obtained with the use of the Langmuir properties and the Henry coefficient ( K H ) was found from the virial equation. The thermodynamic analysis of CO 2 and N 2 adsorption which include the entropy loss (ΔS), the Gibbs free energy change (ΔG) and the surface potential (Ω) was calculated. The results reveal that the order of CO 2 uptake on AC is higher than that of N 2 . α ( CO2/N2 ) decreased with the increase of the temperature. The K H values of CO 2 on the AC are the most important, while the K H values for N 2 are the least. The thermodynamic parameters which include Ω, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi mathvariant="normal">Q</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">st</mml:mi> </mml:mrow> </mml:msub> <mml:mo>,</mml:mo> </mml:math> ΔG and ΔS are impacted by the porous structure of the AC.The adsorption affinity and the adsorption spontaneity of CO 2 is the highest, while N 2 has the lowest adsorption spontaneity. Subsequently, CO 2 exhibits a higher interaction with AC, in contrast to N2 which displays a slight interaction.the obtained results can be used to CO 2 capture and to improve the efficiency of CO 2 adsorption devices.