Innovative Elution Processes for Recovering Uranium from Seawater

Wai, Chien¹  Tian, Guoxin²  Janke, Christopher³ 

[1] Univ. of Idaho, Moscow, ID (United States);Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States);Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

关键词: SODIUM CARBONATES;    URANIUM;    HYDROGEN PEROXIDE;    SEAWATER;    CARBON DIOXIDE;    VANADIUM;    HYDROCHLORIC ACID;    LEACHING;    EXTRACTION;    EFFICIENCY;    COMPARATIVE EVALUATIONS;    SERVICE LIFE;    ADSORPTION;    DESORPTION;    MIXTURES;    POLYMERS;    REMOVAL;    CAPACITY;    ECONOMICS;    LIGANDS;    REGENERATION;    SIMULATION;    AMIDES;    OXIMES;    URANYL COMPLEXES;    TBP;    DAMAGE;   

DOI  :  10.2172/1167189
RP-ID  :  DOE/NEUP--11-3256
PID  :  OSTI ID: 1167189
Others  :  TRN: US1600514

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来源: SciTech Connect

【 摘 要 】

Utilizing amidoxime-based polymer sorbents for extraction of uranium from seawater has attracted considerable interest in recent years. Uranium collected in the sorbent is recovered typically by elution with an acid. One drawback of acid elution is deterioration of the sorbent which is a significant factor that limits the economic competitiveness of the amidoxime-based sorbent systems for sequestering uranium from seawater. Developing innovative elution processes to improve efficiency and to minimize loss of sorbent capacity become essential in order to make this technology economically feasible for large-scale industrial applications. This project has evaluated several elution processes including acid elution, carbonate elution, and supercritical fluid elution for recovering uranium from amidoxime-based polymer sorbents. The elution efficiency, durability and sorbent regeneration for repeated uranium adsorption- desorption cycles in simulated seawater have been studied. Spectroscopic techniques are used to evaluate chemical nature of the sorbent before and after elution. A sodium carbonate-hydrogen peroxide elution process for effective removal of uranium from amidoxime-based sorbent is developed. The cause of this sodium carbonate and hydrogen peroxide synergistic leaching of uranium from amidoxime-based sorbent is attributed to the formation of an extremely stable uranyl peroxo-carbonato complex. The efficiency of uranium elution by the carbonate-hydrogen peroxide method is comparable to that of the hydrochloric acid elution but damage to the sorbent material is much less for the former. The carbonate- hydrogen peroxide elution also does not need any elaborate step to regenerate the sorbent as those required for hydrochloric acid leaching. Several CO2-soluble ligands have been tested for extraction of uranium from the sorbent in supercritical fluid carbon dioxide. A mixture of hexafluoroacetylacetone and tri-n-butylphosphate shows the best result but uranium removal from the sorbent reaches only 80% after 10 hours of leaching. Some information regarding coordination of vanadium with amidoxime molecules and elution of vanadium from amidoxime- based sorbents is also given in the report.