SPECTROSCOPIC STUDY OF THE EXTRACTION OF NICKEL BY 2-HYDROXY-5-NONYLBENZOPHENONE OXIME (LIX 65N) AND 5,8-DIETHYL-7-HYDROXYDODECANE-6-ONE OXIME (LIX 63).

ABSTRACT

A novel method for determination of solvent extraction equilibria and kinetics using Infrared attenuated total reflectance spectroscopy (ATR) is described. The method allows complete, quantitative kinetic studies using a total of one gram of extractant. Solvent extraction of aqueous Ni²⁺ into 0.5 - 1.0 μm films of Apiezon M (ApM, aliphatic hydrocarbon) containing the title reagents was examined. In contrast with LIX 65N extraction which proceeds solely through the LIX 65N anion, extraction of Ni²⁺ by LIX 63 proceeds through both neutral and anionic forms of LIX 63. This results in a kinetic rate law having two terms, each exhibiting first order dependence on both Ni²⁺] and LIX 63]₀. For mixtures of LIX 65N and LIX 63 (LIX 63:LIX 65N ≤ 0.12) In the ApH films, the rate law has only one term, of orders LIX 65N]₀ ¹, LIX 63] ₀ ¹, Ni²⁺]¹, and H⁺]^?1. While the equilibrium constants favor Ni(LIX 65N)₂, the relatively large rate of reaction of the neutral LIX 63 leads to a catalysis of the overall LIX 65N extraction.