Abstract

This paper dealts with solvent and bulk liquid membrane extraction of Ni2+ from its chloride solutions by HDEHP in n-heptane. Effects of extraction time, initial pH and Ni2+ concentration in the feed as well as HDEHP concentration in the organic phase were investigated. Solvent extraction equilibrium was established within 10 minutes. Ni2+ showed to be extracted into the organic phase preferentially as Ni(DEHP), complexes. The Ni2+ extraction yield decreased with increasing initial Ni2+ concentration, with decreasing pH and/or HDEHP concentration. The later is not only due to shifting equilibrium of Nils extraction reaction, but also due to concurent extraction of HCI. Results of bulk liquid membrane extraction could be described by the kinetics of interfacial pseudo-first order reactions. Observed rate constants were determined ⁓ 2,30.10-2 ⁒ 2,68.10-2 min-1 for concentration range [Ni2+]0 ⁓ 10-3 ⁒ 10-2 mol/l.