Extraction of molybdenum with bis(2,4,4-trimethylpentyl)phosphine acid (Cyanex-272)

The influence of different parameters on the recovery of molybdenum by extraction with bis(2,4,4-trimethylpentyl)phosphine acid (Cyanex-272) is considered. It is established that its maximum value is attained at pH ∼2. Using the methods of saturation and the shift of the equilibrium, it is shown that Cyanex-272 extracts Mo from hydrochloric, nitric, and sulfuric acid solutions by the mechanism of the cation exchange with the attachment of two single-charged acidic residues of the dimer of bis(2,4,4-trimethylpentyl)phosphine acid to the molybdenum cation. Based on the data obtained by UV and IR spectroscopy, the structure of the extracted molybdenum compounds is determined. It is shown that it is similar to the structure of the substances that form during extraction using other organophosphorous acids.