Physisorption Kinetics in Carbon Nanotube Bundles

Carbon nanotube bundles hold great promise for adsorption applications. However, most of the work done thus far has focused on the equilibrium properties of adsorption; the kinetics of adsorption is still not well understood. There also exist large discrepancies in the reported uptake of particles in the internal adsorption sites of carbon nanotube bundles. The purpose of this project was to elucidate the kinetics of adsorption in carbon nanotube bundles and to determine what kinetic factors, if any, may have caused the variations in experimental results. We studied the adsorption of particles in carbon nanotube bundles using analytical and computational techniques. By employing these separate but parallel methods, we were able to constantly compare and verify our results. We calculated and simulated the behavior of the system throughout its evolution and then analyzed our results to determine which system parameters had the greatest effect on the kinetics of adsorption. Our analytical and computational results showed good agreement with each other and with the experimental isotherm data provided by our collaborators. As a result of this project, we now know that the equilibration time of a system depends primarily on the binding energy of the adsorbates and the temperature. Specifically, the highest adsorption rates and shortest equilibration times are observed in systems with low binding energies and high temperatures. We also discovered that equilibration time for internal adsorption phases can be several orders of magnitude larger than those for external phases, which may have led to the disagreements in reported experimental results. Because of this work, we now better understand the process of equilibration