Enhancement of oxygen adsorption using biomass-based oxidized porous carbon

The porous carbon adsorbent walnut-shell precursors-based biomass using the Hummer synthesis method was developed for oxidized porous carbon adsorbent. Adsorption-desorption of N2, high-resolution transmission electron microscopy (HRTEM), FESEM, FTIR spectra, and X-ray powder diffraction analyses were used to evaluate the morphology and structure of the specimens. The oxidized porous carbon adsorbent possessed a specific surface area (217.34 m2/g) and pore volume (0.1524 cm3/g). The oxidization process reduced the average volume of mesopores and micropores. Although the specific surface area of the oxidized sample was reduced, the oxygen adsorption capacity was improved by more than 1.4 times. Under 298 K and 9.55 bar pressure, the greatest adsorption capacities for oxygen and nitrogen were specified to be 4.11 (mmol/g) and 3.03 (mmol/g), respectively. The oxygen and nitrogen adsorption on the porous carbon closely was matched by the Fractional-order kinetic and Sips isotherm models, and thermodynamic analysis demonstrated that the physisorption process was confirmed. The improved adsorbent's oxygen adsorption selectivity was remarkable. Oxygen and nitrogen adsorption were increased by oxidized adsorbent by 40% and 14%, respectively. Ultimately, oxygen can be adsorbed by the oxidized sample with more efficiency than nitrogen gas.