Collection of uranium in sea-water, (7). Desorption of uranium adsorbed on titanic acid

A basic study was carried out on the desorption of uranium adsorbed on titanic acid, using alternatively, a mixed solution of (NH₄)₂CO₃ and NH₄OH, a mixed solution of Na₂CO₃ and NaHCO₃, dilute H₂SO₄ or dilute HCl. The titanic ocid used was prepared by homogeneous precipitation, in which urea was added to Ti(SO₄)₂ solution and then the solution was heaed to produce titanic acid precipitate. Uranium was adsorbed by dipping the titanic acid in naural sea water. The results obtained were as follows. In the case of uranium desorption with carbonate solution, there was little dissolution of the titanic acid and of impurities in the solution after desorption, but the drawback of this agent is its expensiveness and it is further liable to be gradually consumed upon repeated use. Desorption with acid, while it was believed to have the disadvantage of dissolving titanic acid in much greater quantity, proved upon experiment not to be any worse than with carbonate. The cost of acid, moreover, is lower, and there is little deterioration of the adsorption ability of titanic acid because of the little amount of impurities remaining in it. The foregoing observations lead to the conclusion that desorption with acid could be used in practice with good chances of rivaling the carbonate method. For the desorption, it is recommended to heat above 90℃ the titanic acid carrying the uranium in HCl (0.5N) or in a mixed solution of Na₂CO₃/NaHCO₃(8/2 to 0/10) containing over 6% CO₃. (author)