Effect of humic acid on the solid phase stability of UO2CO 3

Abstract

The stability of UO2CO3 has been studied as a function of the humic acid concentration in 0.1M NaClO4, in the weak acidic pH range (4.5-5) under CO2 atmosphere. 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, UO2CO3 is stable and remains the solubility limiting solid phase even in the presence of increased humic acid concentration in solution. However, humic acid affects texture and particle size of the solid phase. Increasing humic acid concentration results in decreasing crystallite size of the UO2CO3 solid phase. Based on the solubility data, the logK sp (UO2CO3) has been evaluated to amount -13.7±0.2 for the humic acid-free system and -13.2±0.3 for the humic acid containing system. © 2009 Akadémiai Kiadó.