CO₂ adsorption by KOH-activated hydrochar derived from banana peel waste

Hydrothermal carbonization is one of the effective methods of converting wet lignocellulosic biomass into carbon-rich hydrochar. Due to its characteristic application on CO₂ capture and storage, many researchers have studied the CO₂ uptake on activated hydrochar. The present work studies the CO₂ uptake from banana-peel-derived activated hydrochar which is not presented in the literature. Hydrochar is obtained at three different temperatures (180, 200, and 220 °C) and activated using KOH. Characterization studies including SEM, XRD and FTIR were performed to examine the structure and chemistry of the derived activated hydrochar. The hydrochar sample (BP-180) when activated with a KOH/hydrochar ratio of 3 and an activation temperature of 700 °C has a well-developed microstructure with a surface area and pore volume of 243.4 m²/g and 0.0931 cm³/g, respectively. Samples obtained at higher process temperatures (BP-200 and BP-220) showed much lower porosity. Similarly, the maximum CO₂ adsorption is recorded for BP-180 (3.8 mmol/g), followed by BP-200 and BP-220 with maximum adsorption capacities of 3.71 and 3.18 mmol/g, respectively, at 1 bar and 25 °C.