Studies on kinetics and thermodynamics of ion adsorption reactions by applications of short-lived radioactive tracer isotopes

The short-lived radiotracer isotopes were applied to study the kinetics and thermodynamic feasibility of iodide as well as bromide ion adsorption reactions using industrial-grade resin materials. Free energy of activation (ΔG‡) and energy of activation (Ea) were calculated by using Arrhenius equation, enthalpy of activation (ΔH‡), and entropy of activation (ΔS‡) calculated by using the Eyring-Polanyi equation. These parameters were used to predict the thermodynamic feasibility of the two ion adsorption reactions performed by using Dowex SBR LC and Indion-810 resins. It was observed that during iodide ion adsorption reactions, the values of energy of activation (−18.79 kJ mol−1), enthalpy of activation (−21.37 kJ mol−1), free energy of activation (58.13 kJ mol−1), and entropy of activation (−0.26 kJ K−1 mol−1) calculated for Indion-810 resins were lower than the respective values of −4.28 kJ mol−1, −6.87 kJ mol−1, 64.97 kJ mol−1, and −0.23 kJ K−1 mol−1 calculated for Dowex SBR LC under similar experimental conditions. Identical trends were observed for the two resins during bromide ion adsorption reactions. The low values of different thermodynamic parameters obtained for Indion-810 resins during both the ion adsorption reactions indicate that the reactions are thermodynamically more feasible using Indion-810 resins as compared to Dowex SBR LC resins. It is expected here that the present nondestructive technique can be extended further for different ions in the solution in order to predict the thermodynamic feasibility of different ion adsorption reactions for the range of resins which are widely used for treatment of industrial waste water effluent.