Microporous carbon derived from cotton stalk crop-residue across diverse geographical locations as efficient and regenerable CO2 adsorbent with selectivity.

Six porous carbons (PCs) were prepared via thermochemical methodology from cotton-stalk crop residue, collected from diverse geographical locations in India. Although similar in nature, the precursor collection sites majorly influenced the properties of the generated PCs, possibly due to variations in soil characteristics and fertilizer usage patterns. The microstructures were characterized by a series of analytical data, including FT-IR and Raman Spectra, XRD, TGA, SEM imaging, and in-depth XPS studies. Nitrogen sorption isotherms at 77 K of all PCs revealed well-defined microporosity and high specific surface area, varying from 1706 to 2438 m²/g under similar synthetic conditions. Further, gaseous CO 2 adsorption studies showed that the PCs exhibited diverse uptake performances at 1 bar under varied temperatures. The maximum uptake capacity of 6.23 mmol/g (273 K), 3.85 mmol/g (298 K), and 3.28 mmol/g (313 K) defined superior values over contemporary adsorbents. A critical-point drying technique was employed further to enhance the CO 2 uptake capacity of these carbons. Importantly, all the carbons revealed moderate to good CO 2 /N 2 separation selectivity at low temperature (~25 at 273 K) that experienced a unique enhancement under elevated temperature, as calculated from ideal adsorbed solution theory. After vacuum regeneration, the activated carbons exhibited stable CO 2 adsorption up to five cycles, validating their potential reusability for CO 2 capture. Precisely, the cotton stalk crop residue-derived PCs represent one-of-a-kind low cost, eco-friendly, abundant, and scalable absorbents for regenerable CO 2 capture with moderate heat of adsorption and selectivity values, with promises of practical usability. [Display omitted] • Cotton-stalk crop-residue based porous carbons (PCs) synthesized from diverse geographical locations. • Microporous PCs exhibits surface area > 2000 m²/g and excellent CO 2 adsorption with modest Q st values. • The CO 2 adsorption capacity augments through critical point drying technique. • Temperature variable sorption studies indicate sharp enhancement in CO 2 /N 2 selectivity. • PCs exemplify low-cost, eco-friendly, abundant and scalable CO 2 absorbents for practical applications. [ABSTRACT FROM AUTHOR]