SOLVENT EXTRACTION OF MOLYBDENUM (VI) FROM SULPHURIC ACID SOLUTIONS WITH HEXANOL AND DECANOL

Abstract

Extractive recovery of molybdenum (VI) from sulphuric acid solutions in the presence of KHSO4 as salting out agent using alkanols (hexanol and decanol) has been investigated by solvent extraction, propelled by the need to proffering alternatives to the scarce and relatively costly organophosphorous extractants. The effects of various parameters such as contact time, concentration of sulphuric acid, hexanol and decanol concentrations, temperature, number of extraction stages, loading capacity of extractants, recycling of extractants and addition of foreign ions on molybdenum (VI) extraction were determined. The absorption and infrared spectra of the pure extractants, aqueous and organic phases of the molybdenum (VI) extracted from 5 M and 7 M H2SO4 solution with decanol and hexanol respectively were also measured. It was observed that contact times of 5 and 12 min were sufficient for quantitative extraction of molybdenum (VI) with hexanol and decanol respectively. Increasing concentration of H2SO4 at the studied range (1-8 M) yielded optimum percentage extraction (E%) of 46.0% with hexanol at H2SO4 concentration of 7 M, and 48.5% with decanol at H2SO4 concentration of 5 M for single stage extraction. The optimum extraction temperature for both extractants was 301 K. On the number of required extraction stages, hexanol gave a higher extraction efficiency after six consecutive extractions (E% = 91.0) than decanol (E% = 86.8). In the recycling of extractants, the percentage extraction of Mo (VI) was at peak at first stage with both extractant. All added foreign ions decreased E% for Mo (VI). The found optimum conditions were applied to the extraction of Mo (VI) from TREVO, a standardized food supplement to assess the extraction method. From analytical and spectra data, the extracted complex has been formulated as MoO2(HSO4)2.nROH.