Stoichiometric relation for extraction of zirconium and hafnium from acidic chloride solutions with Versatic Acid 10

The stoichiometric relation for the extraction of zirconium and hafnium from acidic chloride solutions was investigated with Versatic Acid 10. Extraction runs were carried out batchwise at ambient temperature in the pH range from 1.4 to 2.3 for zirconium and from 2.3 to 2.9 for hafnium. The results showed that zirconium was extracted in the form of ZrO2+ rather than Zr4+ and the extracted zirconium was solvated with two molecules of Versatic Acid 10 monomer. In the case of hafnium, it could be concluded that the extracted species of Hf4+ ion with Versatic Acid 10 (HR) was a monomeric compound of HfR4. The equilibrium constant for the extraction of zirconium and hafnium was found to be 4.39×10−4 and 6.92×10−12, respectively, at an ionic strength of 0.1 and at 298 K.