Thermodynamics of CO and CO₂ Adsorption on Uranium Dioxide

Using static volumetric method, adsorption isotherms of CO and CO₂ on UO₂ were measured for temperature range 273-303 K and pressure up to 1 kPa, and corresponding thermodynamic properties were studied. The Langmuir and Freundlich equations are found to describe best the adsorption of CO and CO₂, respectively. The strength of adsorption for CO₂ is much greater than that for CO with maximum adsorption amounts of 0.36 and 1.25 μmol/g respectively in current experimental condition. The heat of adsorption for CO equals to 26 kJ/mol, which indicates the adsorption of CO is physical adsorption. The heat of adsorption for CO₂ decreases from 46 kJ/mol to 37 kJ/mol for increasing adsorption amount from 0.3 μmol/g to 0.8 μmol/g, which indicates both chemical and physical adsorptions of CO₂ take place.