Abstract
A volumetric system was used to assess carbon-based adsorbents for evaluation of the gas separation, equilibrium, and kinetics of oxygen (O(2)), nitrogen (N(2)), and carbon dioxide (CO(2)) adsorption on granular activated carbon (GAC) and functionalized GAC at 298, 308, and 318 K under pressures up to 10 bar. The effects of ZnCl(2), pH, arrangement of the pores, and heat-treatment temperature on the adsorptive capabilities of O(2), N(2), and CO(2) were evaluated. High-performance O(2) adsorption resulted with a fine sample (GAC-10-500) generated with a 0.1 wt % loading of ZnCl(2). The optimal sample structure and morphology were characterized by field-emission scanning electron microscopy, Fourier transform infrared spectroscopy, and powder X-ray diffraction. On the basis of the adsorption-desorption results, the fine GAC provides a surface area of 719 m(2)/g. Moreover, it possessed an average pore diameter of 1.69 nm and a micropore volume of 0.27 m(3)/g. At 298 K, the adsorption capacity of the GAC-10-500 adsorbent improved by 19.75% for O(2) but was not significantly increased for N(2) and CO(2). Isotherm and kinetic adsorption models were applied to select the model best matching the studied O(2), N(2), and CO(2) gas uptake on GAC-10-500 adsorbent. At 298 K and 10 bar, the sip isotherm model with the highest potential adsorption difference sequence and gas adsorption difference compared with pure GAC adsorbent as O(2) > N(2) > CO(2) follows well for GAC-10-500. Eventually, the optimal sample is more effective for O(2) adsorption than other gases.