Abstract
Measurements of the extraction equilibria of copper and zinc with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester dissolved in w-heptane or toluene diluent were carried out at 303 K.
It was found that the extractant (HR) is apt to dimerize in n-heptane diluent. It was clarified that copper and zinc are extracted according to the following equations, respectively, in the low concentration range of the metals.
Cu2+aq+2(HR)2, org⇔CuR2•2HRorg+2H+aq
Zn2+aq+1.5(HR)2, org⇔ZnR2•HRorg+2H+aq
Extraction equilibrium constants, Ke, Cu = 1.0×10-4 and Ke, Zn=2.5×10-2 mol1/2/dm3/2 were obtained. From the above experimental results, it is seen that selective separation of copper and zinc is possible by solvent extraction with the extractant used in this study.
