Comparisons of the Masking Effect of Carboxylic, Amic-Acidic, and Amidic Compounds on Lanthanides and Am Complexation

Abstract

Magnitude of the masking effect of carboxylic, amic-acidic, and amidic compounds through Ln and Am extractions by tetraoctyl diglycolamide (TODGA) is compared, and their properties are studied in this paper. The compounds used are diglycol, ethylenediamine, diethylenetriamine-type, and two other amides (dioxaoctane diamide and nitrylotriacetamide). The results show that below pH 1.2, where carboxylic acids are less dissociated, amide O atoms have higher reactivity with lanthanides than O atoms in carboxyl groups. Seeing the Ln patterns (D(Ln) vs. their atomic number), the compounds primarily show high reactivity, with middle and heavy Ln having a higher charge density than light Ln. Four amide compounds are employed in this work. Those with tertiary amine N atoms have pH dependence on D(Ln) due to protonation and dissociation from amine N atoms. However, amides with no amine N atoms have no pH dependence.