Scopul nostru este sprijinirea şi promovarea cercetării ştiinţifice şi facilitarea comunicării între cercetătorii români din întreaga lume.
Autori: Horga R, Axente D, Pamula A, Chiriac M, Baldea A, Fatu C, Leuca M, Ilies I, Ursu D, Floare C
Editorial: Revista De Chimie, 52(7-8), p.377-381, 2001.
The experimental data on U-235 enrichment by isotopic exchange U-235/U-238 in U4+-UO22+ system on cation exchange resin C-100 (produced by Purolite) and in the system U4+-[UO2Clx](2-x), on anion exchange resin Dowex-1 (Sigma) are presented. In both cases a thermostated glass column was utilised. Cation exchange resin was passed in R-Ti3+ form, then the column was feeded with 0.047M UO2Cl2 solution. According to the isotopic exchange between U4+ fixed on resin and UO22+ from solution U-235 is enriched in the solution phase at the front of U band, and U-238 in the resin phase at the rear of uranium band. The uranium solution which has passed through the column was fractioned, by means of an automatic sample colector, in 100 small fractions. For each,sample fraction uranium content, and uranium isotopic ratio U-235/U-238 were determined. In the case of Dowex-1 the resin was converted in R-Cl form with 5M HCl solution, then 0.1 M UO2Cl2 solution in 5M HCl was feeded in the column, and on the resin were fixed the following complex anions: [UO2Cl3](-), [UO2Cl4](2-). When all resin was passed in R-U(IV) form, the column was feeded with 0.1 M TiCl3 solution in 5 M HCl. According to the isotopic exchange between [UO2Clx](2-x) fixed on resin and U4+ from solution U-235 will be enriched in the resin phase, at the rear edge of uranium band. The effluent from the bottom of the column was collected in small fractions on which uranium content and isotopic ratio U-235/U-238 were determined. All isotopic analysis were performed on SMIT-1 thermoionization mass spectrometer. In both cases presented here, U-235 enrichments were experimentally determined. Temperature increase with 10 degreesC had not a significant effect on U-235 enrichment in U4+-UO22+ exchange system on cation exchange resin C-100. The 235U enrichment was diminished when feed flow rate of the column with Dowex-1 increased two times. The eluent volume, corresponding to the uranium U-235 maximum enrichment was 1428 mL on cation exchange resin, and 692 mL on anion exchange resin.
Cuvinte cheie: U-235 enrichment by isotopic exchange, cation exchange resin C-100, union exchange resin Dowex-1