The desorption of uranium from the granular titanium-activated carbon composite adsorbent (concentration of uranium: 25.5mg/l-Ad), which adsorbed uranium from natural sea water, was examined by the column process with acidic eluent at room temperature. The column operation was able to be carried out without destruction of the granular adsorbent by the generation of the carbon dioxide, and free from disturbance of the eluent flow by precipitate of calcium sulfate dihydrate with sulfuric acid eluent. The amount of acid consumption by the adsorbent was 0.87eq/l-Ad. The alkaline earth metals were eluted in the range of elution volume below 2l/l-Ad, whereas uranium, iron, and titanium were eluted above 2l/l-Ad. Therefore, uranium was separable from the alkaline earth metals which were adsorbed in the most quantity in the adsorbent. In the range of elution volume 2 to 12l/l-Ad, the percentage of desorbed uranium and the concentration ratio of uranium were 80%, 680 with 0.5 N sulfuric acid, and 59%, 490 with 0.5 N hydrochloric acid respectively. The percentage of dissolved titanium (DTI) was 0.3% with 0.5 N sulfuric acid, 0.26% with 0.5 N hydrochloric acid in the same range.
For the purpose of clarifying the distribution of current density around an insulator in ionic solution in an electrodialyzer, the current density flowing in an equivalent circuit was calculated on the assumption that the circuit was around the insulator. The calculation was carried out with the aid of the Kirchhoff's equation. The calculated values were used to obtain the relations between the current density around the insulator and the distance from the insulator, the dimension of the insulator or the covering ratio of the insulator for the current. Thus, it was found desirable to reduce the dimension of the insulator and the covering ratio for the current in order to decrease the concentration of the current.