Improved the CO2 adsorption performance in cobalt oxide nanoparticles in the presence of DES

Abstract

With the rapid industry development in the last decades, air pollution has increased with the increase in carbon dioxide (CO₂). Adsorbents are considered a good candidate for capturing CO₂ owing to their many advantages, such as reusability, low cost, easy operation, and scale-up synthesis. In this study, the synthesis of mesoporous cobalt oxide (Co₃O₄) nanoparticles (NPs) in deep eutectic solvent (DES) is reported by the ultrasound-assisted method to improve the CO₂ adsorption performance. The synthesized Co₃O₄ NPs were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) for investigating morphology, crystallinity, and porosity. CO₂ and N₂ adsorption isotherms of Co₃O₄ NPs synthesized in DES and synthesized in water were measured by quartz crystal microbalance (QCM) at a temperature range of 288.15–308.15 K and pressures of up to 5 bar. In addition, CO₂/N₂ selectivity adsorption on the Co₃O₄ NPs was investigated. Furthermore, adsorption isotherms were correlated to the Langmuir isotherm model. The results reveal that the adsorption performance of Co₃O₄ NPs synthesized in DES improved in comparison with Co₃O₄ NPs synthesized in water. The Co₃O₄ NPs’ molar enthalpy of adsorption showed that the CO₂ adsorption process is exothermic.