Uranium from sea water

The location of uranium from sea water taken up by the alga Dunaliella was achieved by EDAX and the microscope in the STEM mode (Spry and Bochem, 1981). 

Driscoll, M. J., Meeting on Recovery of Uranium from Sea Water, Japan, 1983. 

In view of the anticipated exhaustion of terrestrial uranium reserves in the western world at the beginning of the next century 101), the recovery of uranium from sea water has received much attention over the past three decades 102 U9). First studies on uranium extraction from sea water were carried out as early as 1953 by the Atomic Energy Research Establishment in Harwell (AERE), United Kingdom. Extensive efforts have been made in Japan since the early 1960s from the People s Republic of China activities in this direction have been known since 1970. In the Federal Republic of Germany continuous research on the recovery of uranium from sea water has been in progress since about 1973. Investigations have also been carried out in France, Italy, Soviet Union, Finland, India, and more recently also in the United States and Sweden. 

Preliminary studies on potential methods for the extraction of uranium from sea water took into consideration not only the extraction by solid sorbents, but also by solvent extraction, ion flotation, coprecipitation, and electrolysis. However, for a large-scale uranium recovery only the sorptive accumulation by use of a suitable solid sorbent seems to be feasible with regard to economic reasons and environmental impacts n9). 

A process for recovery of uranium from sea water comprises the regeneration of the sorbent by elution of uranium. Elution should proceed rapidly and with high yield in order to maximize the overall eficiency of the recovery process, which is measured in terms of the increase of the effective concentration, i.e. the concentration of uranium in the eluate compared to the initial concentration in the sea water. Finally, a high selectivity of the elution process is desirable 107,130). A further concentration of uranium in the eluate up to the precipitability in the form of yellow cake can be attained by ion exchange, ion flotation, or electrodialysis. 

Several technical processes have been suggested for the recovery of uranium from sea water using solid sorbents, in particular hydrous titanium oxide. The processes have partially been tested in preliminary model plants. Generally, fixed and fluidized sorbent bed operations can be distinguished. 

The selective extraction of uranium from sea water has attracted extensive attention from chemists because of its importance in relation to energy problems. In order to design a ligand that can selectively extract uranyl ion (UO " ), one has to overcome a difficult problem i.e., the ligand must strictly discriminate UO from other metal ions present in great excess in sea water. A possibly unique solution to this difficult... 

EXTRACTION OR URANIUM FROM SEA WATER BY SYNTHETIC POLYMER ADSORBENT... 

From this point of view, we are studying the extraction of uranium from sea water. It is one of the most important subject in the establishment of the extraction process to develop the excellent adsorbent with the selectivity and high velocity of adsorption for uranium. 

From the results of many investigations of inorganic adsorbents, it has been estimated that hydrous titanium oxide and the composite adsorbents which consist of hydrous titanium oxide and other materials are useful adsorbents in practical use. But the rate of adsorption for uranium from sea water on hydrous titanium oxide or the composite adsorbents is not so large (about 200 yg/g-adsorbent at 10 days). 

It has been tried to prepare polymer resin which has the appropriate structure and functional groups as an adsorbent for extraction of uranium from sea water. 

The extraction of uranium from sea water with the AN-DVB-AO resin was carried out by column method under the condition as follows resin 5g, flow rate of natural sea water 20 ml/min-g-resin, temperature 25 2°C. 

From the results in Section 2, it has been noted that the wettability of the resin is of great importance in the adsorption of uranium from sea water and the AN-DVB-AO resin has less wettability owing to the hydrophobic cross-linking agent of divinylbenzene. 

THE EXTRACTION OF URANIUM FROM SEA WATER WITH THE AN-TEGDM-AO RESIN... 

Table 5. Adsorption of Uranium from Sea Water bv AN-TEGDM-AO Resin...

On the basis of above results, the extraction of uranium from sea water with the AN-TEGDM-AO resin was tried by column method. The results are summarized in Table 5. By repeating adsorption and desorption 5 times the decrease of adsorptive property such as rate of adsorption was not observed. 

Llewelyn G. I. W. Recovery of uranium from sea-water. In Uranium ore processing (Vienna IAEA, 1976), 205-21. 

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