Freundlich, Langmuir, Temkin, DR and Harkins-Jura Isotherm Studies on the Adsorption of CO2 on Various Porous Adsorbents

The objective of the study was to prepare low-cost activated carbon from cornelian cherry stones (Cornus mas L.) and compare its adsorption capacities for CO2 with that of commercial multiwalled carbon nanotubes, activated carbon, MCM-41 and four zeolites (silver exchanged, 13X, faujasite type and linde type A). BET, t-plot and DFT methods were used for the characterization of all adsorbent samples based on N-2 adsorption-desorption data obtained at 77 K. The produced activated carbon samples (KAC and NAC) were also characterized by scanning electron microscopy (SEM). The adsorption data were evaluated by several isotherm models such as Freundlich, Langmuir, Temkin, DR and Harkins-Jura isotherm models. Langmuir adsorption isotherms constants related to adsorption capacity, W-m were found as 11.496, 6.175, 4.189, 3.986 and 3.50 mmol/g for NAC, KAC, faujasite type zeolit, MCM-41 and AC, respectively. The CO2 adsorption capacities of the silver exchanged, 13X, faujasite type and linde type A zeolites were 10.814, 10.241, 14.608 and 13.343 wt%, respectively. Microporous zeolites showed higher CO2 adsorption capacities than the mesoporous MCM-41 and MWCNT. The CO2 adsorption capacity of commercial activated carbon (AC) was found to be 9.428 wt%, while the CO2 adsorption capacities of activated carbons obtained using NaOH and KOH were found to be 13.685 and 15.057 wt%, respectively. The highest CO2 adsorption capacity of 15.057 wt% was achieved with KAC. It could be confirmed that NaOH or KOH activation plays an important role to determine the porous structure and amount of CO2 adsorbed. Results showed that activated carbon produced from cornelian cherry stones is suitable for the adsorption of CO2 and could be used as a low cost effective adsorbent in the capture of CO2.