Effect of humic acid on the solid phase stability and solubility of UO 2(OH)2
SourceJournal of Radioanalytical and Nuclear Chemistry
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The stability and solubility of UO2(OH)2 has been studied as a function of the humic acid concentration in 0.1M NaClO4, in the pH range from 4 to 7 under normal atmospheric conditions. The solid phase under investigation has been prepared by alkaline precipitation and characterized by TGA, ATR-FTIR, XRD, SEM and solubility measurements. According to the experimental data UO2(OH)2 is stable and remains the solubility limiting solid phase even in the presence of increased humic acid concentration in the solution. However, humic acid affects texture and particle size of the solid phase. Increasing humic acid concentration results in decreasing crystallite size of the UO2(OH)2 solid phase. Based on the solubility data, the logKsp(UO2(OH) 2) has been evaluated to be -22.0±0.3 and the stability constant for the UO2(OH)HA(I) species has been estimated to be logβ1101 = 15.3±0.5. © 2008 Akadémiai Kiadó.