Application of D2EHPA for manganese(II) and nickel(II) separation by solvent extraction and polymer inclusion membranes

The separation of manganese(II) and nickel(II) from chloride solution with di-(2-ethylhexyl) phosphoric acid (D2EHPA) was studied. The metal ions were separated using solvent extraction and transport through polymer inclusion membranes (PIMs) with D2EHPA as the extractant/ion carrier. The aqueous solutions consisted of 0.010 M manganese(II) and nickel(II) chlorides. The influence of aqueous phase pH on the separation of Mn(II) and Ni(II) has been investigated. Mn(II) can be selectively removed from chloride solution at equilibrium pH equal to 2.90. From the organic phase, Mn(II) was stripped with 0.1-2.0 M aqueous solutions of HCl, H2SO4 and HNO3. The competitive transport of Mn(II) and Ni(II) through PIMs was studied as a function of the ion carrier and plasticizer concentration in the membrane.