Study of Carbon Dioxide adsorption on Purified HiPco Nanotubes*

We have investigated the adsorption characteristics of carbon dioxide on purified HiPco single-walled carbon nanotubes. We measured four full isotherms (starting from zero CO$_{2}$ coverage an ending at the saturated vapor pressure) for temperatures between 150 K and 187 K. While a linear plot of the adsorption isotherms presents initially a relatively broad region of rapid coverage increase with pressure, logarithmic plots of the isotherms are characterized by the absence of any substeps in the data. The equilibration times for each point along the isotherms are much longer than those for other simple adsorbates (e.g., CH$_{4}$ or Ar) on the same sorbent. Results for the effective monolayer capacity as well as values for the isosteric heat of adsorption's dependence on sorbent loading will be presented.