Solvent extraction of cadmium by dioleylphosphoric acid

The extraction mechanism of cadmium (II) with dioleylphosphoric acid has been investigated in a liquid-liquid extraction system. Dioleylphosphoric acid was found to possess a high extraction potential for cadmium ions. The composition of the complex between a cadmium ion and the extractant was elucidated by slope analysis and by Job's method. The cadmium ion reacts with two dimers of dioleylphosphoric acid in n-dodecane and two protons in the extractant are released to the aqueous phase. The location site of the organometallic complex CdR₂•4HR in the organic solvent has been observed by a light scattering method performed on loaded organic solution to exist in the wall of reversed micelles. Further, the back-extraction was easily achieved by contacting the loaded organic phase with hydrochloric acid solution.