CO2 adsorption behavior of a highly-microporous KOH-activated carbon obtained from rice husk waste: kinetic and equilibrium studies

Abstract In this study, rice husk was the precursor for a KOH-activated carbon with high surface area and high micro-porosity. CO2 adsorption capacity of this material was measured by thermogravimetric analysis. The CO2 adsorption kinetic showed that equilibrium was reached 30 min after the solid-gas phases came into contact and is well-described by the pseudo-first order model (R2 > 0.99 and 95 % confidence level). Intraparticle diffusion model revealed multilinearity over the CO2 adsorption range. Isotherm data at 25, 35, and 45 °C were well-fitted by the Freundlich model, revealing the adsorbent’s surface heterogeneity and the exothermic behavior of the process. The material reached a maximum CO2 adsorption capacity of 2.54 mmol/g. A comparison with literature data showed a good agreement.