Adsorption behavior of zirconium and molybdenum from nitric acid medium using low-cost adsorbent

The highly radioactive waste liquors from the processing of nuclear reactor fuels contain zirconium and molybdenum, which occur among the fission products. Treatment of wastewater by economical and effective methods is very crucial in the area of development and technological advancements. In the present work, the adsorption behavior of Zr(IV) and Mo(VI) on charcoal from nitric acid medium was investigated using batch technique. Variations of the distribution coefficients as a function of HNO3 concentration in the range 0.05-3.0 M were presented. Some of the separation possibilities were pointed out. The obtained results indicate that the selectivity of Zr(IV) is higher than Mo(VI) at high acidities. The adsorption kinetics data following the pseudo-second order model indicated that the rate-controlling step is chemical adsorption. The data also followed the Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms. The values of enthalpy and entropy changes show that the overall adsorption process was endothermic (ΔH > 0) and increasing entropy (ΔS > 0), and it was spontaneous (ΔG < 0). This study shows that the low-cost adsorbent, charcoal, is an effective adsorbent for the retention of Zr(IV) and Mo(VI) species from nitric acid medium. The feasibility of the removal of 95Zr and 99Mo from simulated intermediate level waste solutions was tested.