Characterization and evaluation of low-cost biomass-based-AC for CO2 capture: A review

In this work, several carbonaceous biomass sorbents including Biochar, activated carbon, and cellulose fiber activated carbon were investigated for CO2 capture. There are several methods of preparing activated carbon (AC) from biomass, and the resulting material has a variety of physical properties. Chemical activating agents are applied to increase the surface area and porosity of AC and enhance CO2 adsorption capacity. In comparison to sulfuric acid-activated carbon samples, potassium hydroxide showed a stronger activating effect with higher values for surface area and pore size. A heteroatom, like nitrogen, can also influence the uptake capability of activated carbons. Several ACs derived from biomasses are much more effective at adsorbing CO2 compared with activated carbon (AC). The results revealed that the mean of CO2 adsorption capacity was lying within the range of 2.5–4.8 mmol/g at 25 °C and 1 bar. Meanwhile, the maximum adsorption capacity belongs to yellow mombin stones with 7.3 mmol/g at 25 °C and 1 bar. In addition, the modification study presented that the amine and sulfur groups have a tremendous impact on enhancing the removal of CO2. The cost evaluations have proved that carbon-based biomass had the lowest price relative to the most adsorbents. The adsorption mechanism also revealed that the most mechanism is the chelation of functional groups with the CO2 molecules. The mass transfer study has exhibited that diffusion occurs in both micro-pore and macro-pore, but in micro-pore was more than in macro-pores.