EXTRACTION OF ZINC(II) IONS FROM SULFATE-SOLUTIONS WITH MIXTURES OF N-HEXANOIC ACID AND PENTANOL IN N-DECANE

The extraction of zinc (II) ions with n-hexanoic acid in decane and with n-hexanoic acid and pentanol in decane has been investigated. Very good isolation of zinc ions with n-hexanoic acid alone (5-10 vol%) was found to take place at pH 3.5-4.5. At pH values higher than 4.5 the extraction was impossible due to precipitate formation. The pH range was extended after addition to the system of n-pentanol. Up to 50% of zinc ions could then be isolated in a single extraction step. In both n-hexanoic acid and n-hexanoic acid-n-pentanol systems, zinc ions were transferred into the organic phase as the complex ZnR2.2HR. n-pentanol was not involved in the formation of any ternary complex, but it merely prevented precipitation. The extraction constant was calculated to be K(ex) = 3.25 . 10(-10).