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  • Author or Editor: S. Katsuta x
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Abstract  

The effect of phenols on the ion-pair extraction of chromium(VI) as chromate anion (HCrO 4 ) with tetraphenylarsonium cation (TPA+) has been investigated. By using TPACl, chromate is extracted as an ion-pair, TPA+·HCrO 4 , into organic solvents, but its extractability into nonpolar solvents such as carbon tetrachloride is very low. The addition of several phenols greatly enhances the extractability, e.g., the distribution ratio of chromium(VI) between carbon tetrachloride and water rises 5500-fold in the presence of 0.020M 3,5-dichlorophenol in the organic phase. The enhancement was larger when using more acidic phenols and less polar solvents. From the analysis of the extraction data for the 3,5-dichlorophenol-carbon tetrachloride system, it was shown that one molecule of chromate is extracted together with one TPA+ and 1–3 phenol molecules and the extraction constants were determined. The UV spectrum indicated the extracted species including chromate ester to the TPA+·ArOCrO 3 ·mArOH (m=1,2).

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Abstract  

Effect of 3,5-dichlorophenol (DCP) on the extraction of Fe(III) with acetylacetone (Hacac) in nonpolar organic solvents has been studied. It is found that a mixture of Hacac and DCP in heptane gives much higher extraction of Fe(III) than Hacac alone. Such novel enhancement effect is ascribable to the association of tris(acetylacetonato)iron(III) [Fe(acac)3] with DCP in the organic phase by hydrogen bonding. Association of Hacac with DCP has also been investigated and the intrinsic extraction equilibrium of Fe(III) is analyzed by using the equilibrium concentration of free Hacac and DCP. The association complexes are found to be Fe(acac)3 · n DCP (n=1, 2, 3) in heptane, and the overall association constants ( ass, n) are determined to be log ass, 1 = 3.41, log ass, 2, = 5.97 and log ass, 3, = 7.50.

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