Modeling batch kinetics of cesium, cobalt and strontium ions adsorption from aqueous solutions using hydrous titanium oxide

Hydrous titanium oxide was chemically synthesized and tested as adsorbent material for the removal of cesium, cobalt and strontium ions from chloride waste solutions using batch technique. The influences of pH, contact time, and temperature have been reported. The uptake of both strontium and cobalt ions was found to be greater than that of cesium and the apparent sorption capacity of each ion increases with increase in temperature. Thermodynamic parameters such as changes in Gibbs free energy (ΔG⁰), enthalpy (ΔH⁰), and entropy (ΔS⁰) were calculated. The numerical value of ΔG⁰ decreases with an increase in temperature, indicating that the sorption reaction of each ion was more favorable at higher temperature. The positive values of ΔH⁰ correspond to the endothermic nature of sorption processes and suggested that chemisorption was the predominant mechanism. Analysis of the respective rate data in accordance with three kinetic models revealed that the homogeneous particle diffusion kinetic model was found to best correlate the experimental rate data. The numerical values of the rate constants and particle diffusion coefficients were determined from the graphical representation of the proposed models. The results indicated that prepared hydrous titanium oxide can be used as an efficient adsorbent material for the removal of strontium and cobalt ions from radioactive aqueous wastes.