Extraction of reduced molybdophosphoric and molybdoantimonylphosphoric acids with oxygenated solvents

The extractability of reduced molybdophosphoric acid and molybdoantimonylphosphoric acid depends principally on the solution acidity and the solvent. The effect of acidity is not related to the formation equilibria or stability of the heteropoly acids in the ranges studied (0.0003–2.5 M). A number of solvents extract independently of acidity, which suggests that suppression of dissociation is not a major factor. In certain instances, extraction is related to the ionic strength and acidity rather than just the acidity. The solvent influence can be related to its basicity or ability to solvate the heteropoly anion; Generally, the less basic the solvent, the greater the acidity or ionic strength must be to reach maximal extraction. The effect is probably one of dehydration or salting-out. Butyl acetate and acetophenone appear to be the best choices as extractants for reduced molybdoantimonylphosphoric acid based on minimal mutual solubility, acidity dependency, and extraction efficiency.