Recovery of uranium from carbonate solutions using strongly basic anion exchanger: 4. Column operation and quantitative analysis

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• 作者：Song ; Yinjie ; Wang ; Yan ; Wang ; Lianhe ; Song ; Chengxing ; Yang ; ZhangZhun ; Zhao ; Aimin
• 关键词：Ion exchange ; Uranium carbonate ; Loading capacity
• 刊名：Reactive and Functional Polymers
• 出版年：1999
• 出版时间：March 15, 1999
• 年：1999
• 卷：39
• 期：3
• 页码：245-252
• 全文大小：189 K

文摘

A process scheme for effectively recovering uranium from dilute solutions, particularly from alkaline carbonate solutions, is developed. The uranyl quadrivalent complex anions [UO₂(CO₃)₃]⁴⁻ are made unstable at pH 6.5–8.5 so that they are partly converted into U₂O₇²⁻ anions in resin phase and mostly exist in the form of [UO₂(CO₃)₂]²⁻ in solution, except for a certain amount of H_n[UO₂(CO₃)₃]⁽ⁿ⁻⁴⁾ (n=0–3). The conversion causes (1) greater than 2-fold of uranium loading capacity at pH 6.5–7.5 referred to that obtained from conventional ion-exchange mechanism, and (2) the minimum ratio between the moles of CO₂ released from the reaction of hydrochloric acid with uranium loading resin and that of uranium loaded by the same amount of resin. The optimum pH range is sensitive to the composition of the solution, such as Cl⁻ and HCO₃⁻ concentrations, although the SO₄²⁻, CO₃²⁻, HCO₃⁻ and Cl⁻ cannot make a great deal of difference in uranium loading capacity because the selectivity sequence of some anions for the resin used is [UO₂(CO₃)₃]⁴⁻NO₃⁻SO₄²⁻≈CO₃²⁻>HCO₃⁻>Cl⁻. The major amount of uranium which cannot be eluted with 1 mol/l NaCl can be easily removed with 1 mol/l NaNO₃, suggesting the selectivity of anions for the resin used should be considered as the main factor during distinguishing uranium in resin phase.