Spectrophotometric study of the uranyl monobenzoate complex at moderate ionic strength

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>The protonation of benzoate and the complexation of uranyl monobenzoate in NaClO<SUB>4</SUB> solutions ranging from 0.1 to 0.5 M were quantitatively investigated by means of ultraviolet–visible (UV–Vis) spectrophotometry. The spectrophotometric study revealed that the uranyl monobenzoate species has a significantly enhanced absorption than that of free uranyl, especially in the UV region. The non-linear regression analysis of the UV–Vis absorption data was the first to calculate the protonation constant of benzoate and the stability constant of uranyl monobenzoate at moderate ionic strength. Based on the SIT (specific ion interaction theory), the protonation constants were extrapolated to the zero ionic strength as log β P ° = 4.21 ± 0.01, and the ion interaction coefficient of the benzoate anion with the sodium cation was determined as ε ( <SUP> Ben - </SUP> , <SUP> Na + </SUP> ) = 0.17 ± 0.05 kg·mol<SUP>−1</SUP>. In the same manner, the stability constant of uranyl monobenzoate at zero ionic strength and the ion interaction coefficient of the uranyl monobenzoate cation with perchlorate anion were determined to be log β U ° = 2.91 ± 0.01 and ε ( <SUP> <SUB> UO 2 </SUB> B e n + </SUP> , <SUP> <SUB> ClO 4 </SUB> - </SUP> ) = 0.22 ± 0.07 kg·mol<SUP>−1</SUP>, respectively.</P> <P><B>Graphical abstract</B></P> <P>The stability constants and spectroscopic properties of the uranyl monobenzoate complex in 0.1–0.5 M NaClO<SUB>4</SUB> medium were investigated by UV–Vis spectrophotometry. The ion interaction coefficient of the uranyl monobenzoate cation with perchlorate anion was determined based on the SIT for the first time.</P> <P>[DISPLAY OMISSION]</P>