Molybdenum(VI) oxosulfato complexes are studied by spectroscopy at 400-640 degrees C. A characteristic Raman band is observed at 935 cm(polarized). Another spectral feature is the presence of a high-energy Raman mode at 895 cm(polarized). The coordination of sulfate groups with the Mo(=O)(2) modes and the partial disconnection of S2O72- from MoO2(SO4)(3) at high temperature are observed.
Spectral analysis was performed to investigate the extracted species. Infrared spectrum was also used to study the stripping process.
Optimal extraction of Mo(VI) occurred at 0.15 mol dm-3 initial aqueous sulfuric acid concentration. This occurs due to the electrostatic attraction of the heteropolyacid anion. As the charge density increases, the extractant rate of this anion increases.
Extraction of Mo(VI) can be carried out by using organophosphorus or chelating reagents. It has the advantage of preventing precipitation of tungstic acid. Consequently, it is a better choice for the separation of Mo(VI).
Extraction of vanadium and molybdenum can be carried out in aqueous solutions. Both ions are soluble in organic solutions. An efficient separation of the two metals is possible, and may be useful for industrial production in the future.
The separation of vanadium and molybdenum was analyzed by co-extraction. Various stripping methods were tested for the study of this process. Among them, the selective stripping method was studied.
The results showed that the extraction rates of molybdenum and vanadium decreased as the pH value increased. In addition, the stripping percentage was higher for the initial aqueous sulfuric acid concentration than for the optimum one.
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