Evaluation of CO₂ adsorption capacity with a nano-CaO synthesized by chemical combustion/ball milling

The adsorption of CO₂ on a nano-calcium oxide (nano-CaO) adsorbent was investigated under different conditions of temperature and supply pressure, considering kinetic, isotherm, and thermodynamic parameters. CaO is a crystalline material with a high surface area and nanosized particles with high porosity, which showed rapid initial CO₂ adsorption rates in the moderate temperature range studied. The adsorption was well described by the pseudo-second-order and the intraparticle diffusion kinetic models. The Langmuir isotherm model fitted the experimental data well, indicating a monolayer-type process. The thermodynamic parameters revealed that the CO₂/nano-CaO adsorption was endothermic, not spontaneous, and proceeded via physical and chemical processes. The activation energy value confirmed that the mechanism involved is a chemical process. In addition, the nano-CaO adsorbent could be regenerated five times without any significant loss of performance or properties. All the obtained results reveal that this porous nanoadsorbent has huge potential to be applied for CO₂-capture technologies on a large scale.