https://doi.org/10.3390/sym13050807
“Figure 20 depicts the adsorption trend of CO2 gas in Akrosorb soda-lime and molded Bentonite ball adsorbents for 0–60 min and 35 °C temperature. A sharp rise in adsorption of CO2 was observed in the first 0–10 min to attain adsorption of 192.0 mg CO2/g and 38.35 mg CO2/g for Akrosorb soda-lime and molded Bentonite ball adsorbents, respectively. This could be attributed to the availability of a sufficient adsorption site per unit mass of adsorbent in the first 0–10 min of adsorption. In addition, for both Akrosorb soda-lime and molded Bentonite ball adsorbents, the rate of CO2 adsorption increases slightly from 192 to 286.40 mg/g and 38.35 to 65.87 mg/g respectively as time increases from 10 to 30 min. However, as the adsorption time increases beyond 30 min to 60 min, the curve for both Akrosorb soda-lime and molded Bentonite ball adsorbents tends to flatten, reaching maximum adsorption of 314.30 mg/g and 68.90 mg/g at 60 min. This is attributed to the fact that a further increase in time beyond 30 min resulted in the adsorption sites getting saturated gradually and the acceptance rate being regulated by the rate at which the CO2 gas is been moved from the exterior of the adsorbent to the internal part, and as such, the adsorption rate became much slower.”
“Figure 20. CO2 adsorption capacity.”
“Furthermore, it was noted that the Akrosorb soda-lime adsorbent exhibited a higher adsorption capacity than the molded Bentonite balls adsorbent. This could be attributed to the higher surface and pore area associated with the Akrosorb soda-lime adsorbent with 1072 m2/g surface area when compared to that of the molded Bentonite adsorbent with 498.2 m2/g surface area, respectively. In addition, the pore volume of the Akrosorb soda-lime adsorbent was in the range of 0.02478–0.3810 m3/g, which was much higher than those of molded Bentonite balls adsorbents in the range of 0.02364–0.1770 m3/g, while the cumulative adsorption pore volume was also established from the Branuer–Emmett–Teller analysis to be 0.5444–0.5566 m3/g for the Akrosorb adsorbent, which was more than twice that of the molded Bentonite ball (0.2533–0.2665 m3/g). The low adsorption capacity associated with Bentonite could be attributed to the fact that Bentonite, though proven to be efficient in removing many toxic materials, particularly metallic, organic, and gaseous contaminants, has a low ability to absorb organic and gaseous molecules such as CO2 and the active site is not uniform. As such, a solution is needed to improve its adsorption performance. Hence, the adsorption rate for both Akrosorb soda-lime and molded Bentonite ball adsorbents decreases with increases in adsorption time due to the attainment of equilibrium.”