Abstract
Microporous carbon compartments (MCCs) were developed via controlled carbonization of wheat flour producing large cavities that allow CO2 gas molecules to access micropores and adsorb effectively. KOH activation of MCCs was conducted at 700 °C with varying mass ratios of KOH/C ranging from 1 to 5, and the effects of activation conditions on the prepared carbon materials in terms of the characteristics and behavior of CO2 adsorption were investigated. Textural properties, such as specific surface area and total pore volume, linearly increased with the KOH/C ratio, attributed to the development of pores and enlargement of pores within carbon. The highest CO2 adsorption capacities of 5.70 mol kg−1 at 0 °C and 3.48 mol kg−1 at 25 °C were obtained for MCC activated with a KOH/C ratio of 3 (MCC-K3). In addition, CO2 adsorption uptake was significantly dependent on the volume of narrow micropores with a pore size of less than 0.8 nm rather than the volume of larger pores or surface area. MCC-K3 also exhibited excellent cyclic stability, facile regeneration, and rapid adsorption kinetics. As compared to the pseudo-first-order model, the pseudo-second-order kinetic model described the experimental adsorption data methodically.
Highlights
With increasing CO2 emissions, global warming is accelerated, accompanied by abnormal climate changes[1,2]
Wheat flour changed to microporous carbon compartments (MCCs), which is composed of flakes forming big compartments; these compartments contribute to high surface area and pore volume (Fig. 1b)
As shown in the TEM image (Fig. 1d), MCC-K3 exhibited worm-like micropores distributed randomly through the carbon
Summary
With increasing CO2 emissions, global warming is accelerated, accompanied by abnormal climate changes[1,2]. Adsorption is considered to be an efficient technology for capturing CO2 because of its low energy consumption and facile regeneration, without the production of pollution or by-products[8]. Porous carbons can be used for the adsorption of CO2 even under humid conditions, attributed to their hydrophobic properties; they exhibit advantages of large surface area with high porosity, rapid adsorption–desorption kinetics, thermal and chemical stability, as well as cost-effective preparation[10]. Several studies have attempted to correlate CO2 adsorption capacity and textural properties, such as surface area and pore volume, for activated porous carbon[20,21,22]. The obtained porous carbon exhibited a high specific surface area of 1700 m2 g−1 and pore volume of 0.79 cm[3] g−1, the values of which are approximately five times greater than those of carbon without activation. The textural properties of the samples prepared significantly depend on the ZnCl2/C ratio
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