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The sorption edges and the sorption isotherms of UO22+onto alumina were determined by a batch technique in the presence and absence of phosphate at pH range 3–6, ionic strength range 0.05–0.5 mol/L and UO22+concentrations 10-5–10-4mol/L. The dependence of sorption percentage of UO22+onto Al2O3as a function of initial concentration of phosphate was also investigated. The effects of phosphate and ionic strength on the sorption of UO22+onto Al2O3as a function of pH were emphatically investigated. It was found that the pH value and the presence of phosphate play a very important role in the UO22+sorption onto Al2O3, even if the concentration of phosphate is only a half of the concentration of UO22+. The sorption steeply increases with increasing pH from 3 to 6, and the sorption is enhanced with increasing concentration of phosphate at sorption percentage lower than 97%. The ionic strength is insensitive to UO22+sorption in the ionic strength range from 0.05 to 0.1 mol/L KNO3, while the sorption is slightly decreased with increasing ionic strength from 0.1 to 0.5 mol/L. The enhanced sorption of UO22+is attributed to the formation of ternary surface complexes involving UO22+and phosphate.

1,1,1-tris(N,N-diisobutylcarbamoyl-methyleneoxymethyl)propane (L) has been prepared and characterized by using IR, 1H NMR and positive-ion FAB mass spectra. The extraction of Th4+and UO22+with L was studied as a function of concentration of free extractant in an organic phase and of picrate in an aqueous phase from a picrate-nitrate medium at 293±1K. It was found that the extractability of L for Th4+is larger than that for UO22+. Both extraction % of Th4+and UO22+decreased with an increase in the concentration of HNO3. The mechanism of extraction of Th4+with L was proposed. The composition of extracted species of L with Th4+in the organic phase is ThL(Pic)2(NO3)2. The results of extraction of trace 234Th4+with L from the picrate-nitrate medium containing UO22+(the initial concentration of UO22+, C0UO₂²⁺=1.23×10-4mol/dm3(M)) agreed well with those from the extraction of single component solutions. The tripodand is useful in separation of Th4+and UO22+from each other in picrate-nitrate media with a relatively high separation factor.

The adsorption and desorption of radioiodine in a calcareous soil from Jiuquan County of Gansu Province (China) was studied using batch and column experiments. The adsorption and desorption isotherms and the breakthrough curves for the untreated soil and for soil treated to remove organic matter were determined at pH 8.1 and in the presence of CaCl2, respectively. It was found that radioiodine is a very mobile nuclide in calcereous soil, that the organic matter of the soil is the main component for the retention of radioiodine at very low concentration and that intra-organic diffusion of matter is the predominant rate-limiting step in the adsorption of the I−ion. It may be concluded that organic matter is a significant sink for radioiodine in calcareous soil.