Extraction Equilibria of Copper(II) with D2EHPA in Kerosene from Aqueous Solutions in Acetate Buffer Media

Abstract

Extraction equilibria of copper(II) from aqueous acetate buffer solutions with di-(2-ethylhexyl)phosphoric acid (D2EHPA) dissolved in kerosene and the stripping equilibria were investigated. Results showed that acetate ions can greatly improve the copper(II) extraction efficiency. The distribution coefficients were significantly dependent on the concentration of acetate ions and the pH value in the aqueous phase because of various mechanisms of extraction and complex formation in the organic phase. With the initial pH value of 4.44 and the acetate ion concentration of 0.18 mol·L-1, the maximum distribution coefficient was observed. In addition, mechanisms of copper(II) extraction in acetate buffer media were established. In the stripping process, the ability to back-extract copper(II) from the organic phase is HCl > H2SO4 > H3PO4.