KOH-activated carbon from pomelo peels for CO₂ adsorption: influence of activation and adsorption process parameters

This study examines pomelo peel-based activated carbon (PMAC) as a promising and sustainable carbon dioxide (CO₂) adsorbent through a systematic exploration of the influence of activation and adsorption process parameters. Investigations into the effects of the activation parameters revealed that the best potassium hydroxide (KOH) activation conditions were achieved with a KOH to pomelo peel-based char mass ratio of 3:1, an activation time of 1.5 h, and an activation temperature of 700 °C. The resulting activated carbon, designated as PMAC-3-1.5-7 (where 3, 1.5, and 7 represent the KOH ratio, activation time in hours, and temperature in hundreds Celsius, respectively), exhibited the highest CO₂ uptake of 254.3 mg/g at 25 °C and 30 bar. Additionally, the response surface methodology (RSM) optimisation method applied to the adsorption process parameters indicated that the maximum adsorption capacity (203 mg/g) occurred at an adsorption temperature of 25 °C, a pressure of 30 bar, and a 50% CO₂ composition in the CO₂-N₂ gas mixture within the parametric study. These findings demonstrate the potential of pomelo peel-based activated carbon as a sustainable and effective adsorbent for CO₂ capture, offering valuable insights into the effects of activation and adsorption process parameters on its CO₂ adsorption performance.