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

Abstract

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.