One of the notable features of carbon nanotubes (CNTs) is their ability to precisely regulate the flow of liquids and gases through their channels, as well as their excellent performance in permeability as next-generation separation membranes. In fact, the transport of fluids through single-walled carbon nanotube (SWCNT) and multi-walled carbon nanotube (MWCNT) membranes, which are functionalized for high permeability and selectivity, has proven to be significantly superior compared to alternative structures. In this study, the surface adsorption of carbon dioxide on carbon nanotubes functionalized with carboxyl (-COOH) and zwitterionic functional groups, along with some of their thermal properties have been investigated using molecular dynamics simulation. Some parameters such as surface coverage, radial distribution function, mean square displacement, and some thermodynamic properties were computed. The impact of functionalization was assessed by evaluating the CO₂ adsorption capacity and the suitability of these functionalized nanotubes as gas separation membranes under specific temperature and pressure conditions. Findings indicate that gas adsorption on zwitterion-functionalized nanotubes decreases considerably when compared to those functionalized with COOH groups. In contrast, there is no significant kinetic barrier to the passage and diffusion of gases into carboxyl-functionalized carbon nanotubes. Molecular dynamics simulations revealed that at least more than three zwitterionic groups at the ends of the nanotubes are required to significantly reduce CO₂ flow. The results of this research are in complete agreement with both simulated data and experimental findings. Functionalized carbon nanotubes exhibit significant promise for advancing technologies in hydrogen storage, gas separation processes, and energy management systems.