CO2/CH4 adsorption over functionalized multi-walled carbon nanotubes; an experimental study, isotherms analysis, mechanism, and thermodynamics

Abstract Understanding of the interactions of the CO2 molecules with pore structure and surface functionalities during natural gas purification provides significant knowledge about potential adsorbent materials. This study reports the oxygen-rich surface functional groups attachment on MWCNTs followed by characterization, low-pressure selective CO2/CH4 adsorption behavior, the impact of temperature, isotherms analysis, mechanism study, thermodynamic behavior, turnover frequency, and turnover number analysis. The FESEM and TEM analysis revealed some negligible defect on MWCNTs surface. The MWCNTs surface roughness was observed after ultra-sonication with the attachment of oxygen functionalities without opening ends of MWCNTs. Structural sustainability and thermal instability were observed due to the early decomposition of (-COOH) groups at