Interaction of Long-Chain Alcohol “Modifiers” With Lix Solvent Extraction Reagents

The effect of two long chain alcohols, n-tridecyl alcohol (TDA) and 2-(l,3-trimethylbutyl)-5,7,7-trlinethyloctanol (ODA) on the extraction of Cu by alkylated hydroxyaldoximes in heptane was investigated by extraction equilibrium determination and infrared spectroscopic examination. The formation of an alcohol-extractant association complex quantitatively explains observed decreases in Dcu that accompanies alcohol addition. Further, an examination of Interfacial activity in these systems demonstrates that, whereas alcohol addition decreases the extractant adsorption at the interface, this cannot be attributed to simple displacement (the extractants are significantly more surface active than the alcohols) but rather to its depletion resulting from the formation of the poorly surface active extractant-modifier complex. Values for the Cu-hydroxyaldoxime extraction constants, self-association constants of the extractants, and the alcohols and extractant-modifier complex formation constant are presented. The critical role of infrared spectroscopic measurements in this study is described.