Extraction behavior of carrier-free and macro amounts of molybdenum and tungsten from HCl solution

Solvent extraction behavior of carrier-free Mo and W from 0.1–11 M HCl into 0.05 M Aliquat 336-chloroform solution was investigated and compared with that of macro amounts of Mo and W. The distribution ratios of carrier-free Mo and W were in good agreement with those of macro amounts of Mo and W in 6–11 M HCl, while the extraction efficiencies of carrier-free Mo and W were different from those of macro amounts of Mo and W in <6 M HCl. Therefore, it appears that the carrier-free as well as macro amounts of Mo and W form mononuclear species in 6–11 M HCl. The disagreement in <6 M HCl is probably due to the formation of polynuclear species of the macro amounts of Mo and W.