Extraction of bismuth(III) with 2-bromoalkanoic acid in nondonating solvent from highly acidic aqueous solution
The extraction behavior of bismuth(III) with carboxylic acids (HL) has not been fully understood, primarily due to interference from hydroxide precipitation. In this study, the extraction of bismuth(III) was investigated using 2-bromoalkanoic acids in benzene and hexane under aqueous conditions with high acidity (I = 1.0 M, (H,Li)NO3). The extraction equilibria were analyzed based on the initial concentration of nitric acid and the amount of bismuth(III) extracted into the organic phase. The results revealed that the extracted species and their respective logarithmic extraction constants (log Kex) were as follows: for the 2-bromooctanoic acid/benzene system, the extracted species was BiL3(HL)3 with log Kex = -1.66, and for the 2-bromohexadecanoic acid/benzene system, it was BiL3(HL)3 with log Kex = -1.58. In contrast, the 2-bromooctanoic acid/hexane system showed two species, BiL3(HL)4 (log Kex = -1.01) and Bi3L9HL (log Kex = -1.62), with the monomer (BiL3(HL)4) being the dominant species at higher reagent concentrations.