Development of composite activated carbon from mango and almond seed shells for CO2 capture.

The continuous emission of CO₂ from anthropogenic activities poses a severe challenge to environmental sustainability. Activated carbon from bio-wastes has evolved as a cost-effect and efficient adsorbent for sequestering harmful gases like CO₂. This study investigates the adsorption of CO₂ using composite activated carbon from almond and mango seed shells. Three (3) different samples, including the activated almond seed shell (AC-KA), the mango seed shell (AC-KM), and the almond-mango seed shell composite (AC-KAM), were developed using KOH as an activating agent at 380 °C and characterized to determine their suitability as adsorbents. The nitrogen adsorption–desorption isotherms indicate that the activated carbon samples are type I microporous solids. The BET results showed that the AC-KM had the highest specific surface area of 629 m²/g and an average pore diameter of 2.12 nm, followed by the composite AC-KAM sample with a BET surface area and pore diameter of 380 m²/g and 1.78 nm, respectively. The SEM–EDX results showed that the composite AC-KAM had the highest atomic carbon percentage of 59.23%, making it a relatively good source of activated carbon. The FTIR analysis indicated the presence of similar functional groups, especially the primary amine group, with a high affinity for acid gases, in all three samples. The CO₂ adsorption experiment results showed that the Langmuir equation adequately modeled the AC-KAM adsorption process, with an adsorption capacity of 1.6245 mmol/g at 26 °C. A Freundlich exponent of n > 1 showed that the adsorption process was favorable. Therefore, the AC-KAM sample can be used as an adsorbent for ambient low-concentration CO₂ capture. [ABSTRACT FROM AUTHOR]