Extraction Of Uranium(Ⅵ) Ions From Aqueous Solutions Using Zirconyl-molybdopyrophosphate-tributyl Phosphate

Uranium resources are the core of the development of nuclear energy, and there is a lot of uranium in sea and salt lakes. Therefore, it is imperative to carry out the study of enrich uranium in water.The extraction efficiency of new organic-inorganic compounds adsorbent for U(VI), namely zirconyl-molybdopyrophosphate-tributyl phosphate (ZMPP-TBP), has been studied. And eleven similar adsorbents are employed to compare with it. To quantitatively evaluate its effect, adsorption of uranium(VI) were test in various aqueous systems, such as pure uranium solutions, salt lake water and uranium mine water,. Effects of pH, temperature, competitive adsorption and nature of ligand were studied both in continuous extraction and batch experiments, the results indicate that the adsorption capacity of ZMPP-TBP increased with increasing of uranium concentration, and190mg/g for most; the adsorption capacity of uranium decreased with increasing temperature in the range of20～80℃; the pH value in range of2-10and coexisting ions which is as10times as U ions did not impact the adsorption efficiency of ZMPP-TBP. The kinetics and thermodynamic properties of adsorption process are studied. The experimental result shows that:the adsorption of uranium(VI) follows the pseudo second-order kinetic model; the ΔH value,-47.529KJ/mol, and the Δs value,-143.856J/mol·k, which indicate that the adsorption is an exothermic process, the increasing temperature could adversely affect the adsorption process. With the increasing temperature, the Gibbs free energy function changes from negative to positive, which indicate the existence of chemical adsorption.The adsorption materials are investigated in microscopic field by using SEM, TEM, XRF, XRD and BET. The analysis of SEM and TEM shows that the ZMPP-TBP has a large specific surface area, and the petal-like structure caused the existence of flat pits, edges, sharp corners, and other configurations, which is beneficial to the adsorption process. BET analysis showed that the specific surface areais68.298m2/g, it can give more adsorption sites, higher surface energy and more surface charge. XRF analysis indicated that the adsorption material contains large amount of phosphorus, which is43.82%, it can improve the adsorption capacity and selectivity of the adsorbent.