Extraction Equilibrium of Ni(II) in the Ni2+-SO42--Ac-(Na+, H+) - Cyanex 272 (H2A2)-kerosene-3%(v/v) Octan-1-ol System

The title system has been studied elaborately. 3% (v/v) octan-1-ol is added as de-emulsifier. Equilibration time is < 2 min. Distribution ratio (D) at constant pH(eq) and [H2A2] is independent of [Ni(II)](aq). The pH dependency is always found to be 2; whilst the extractant dependence is found to vary from 1 (at lower concentration region, lcr) to 3 (at high concentration region, hcr). Moreover, the distribution ratio is found to be inversely proportional to (1+6.92 [SO42-]) and [Ac-]. Based on these results, the extraction equilibrium reactions have been proposed at various parametric conditions. The extraction process is endothermic (?H = 54.66 kJ/mol). The Kex values at 303 K are evaluated to be 10-11.086 and 10-11.56 at lcr and hcr of extractant, respectively. The maximum loading capacity is 21.28 g Ni(II) per 100 g extractant indicating the formation of NiAcA at maximum loading. The stripping ability of various inorganic acids towards loaded nickel, as well as, the possibilities of separation of Ni(II) from its binary mixtures with other ions of 3d-block elements have also been investigated.Keywords: Extraction equilibrium; Ni(II) extraction; Cyanex 272; Sulphate-acetato medium; Kerosene-octanol.