Kelex

A number of chelating cation exchangers have been used as extractants. The modes of complex formation by acylthioureas (32) are described in Section 9.17.6.3 382-385 Their use has been extended to membrane systems for the recovery of Pd 392 The use of Kelex 100297 and of hydroxy-oximes14,297 (Table 3) has been reviewed and methods for improving rates of phase transfer have been surveyed by Szymanowski.14... 

Kyuchoukov, G. Jakubiak, A. Szymanowski, J. Cote, G. Extraction of zinc(II) from highly concentrated chloride solutions by KELEX 100. Solvent Extr. Res. Dev. Jpn. 1998, 5, 172-188. 

Alam, M. S. Inoue, K. Extraction of rhodium from other platinum group metals with Kelex 100 from chloride media containing tin. Hydrometallurgy 1997, 46, 373-382. 

Al-Bazi, S. J. Freiser, H. Phase-transfer catalysts in extraction kinetics palladium extraction by dioctyl sulfide and KELEX 100. Inorg. Chem. 1989, 28, 417 120. 

Solubility data on the LIX and Kelex extractants indicate that these materials are poorly soluble in aqueous media. Accordingly, in plant operations at about pH 1.5, reported losses are approximately <15 ppm, which includes both soluble and entrainment losses as determined by inventory (detailed later in Table 7.6). The solubility of LIX 63, LIX 64, and LIX 64N in water at pH 4.8 has been reported at 5.8, 4.3, and 6.2 ppm, respectively [20]. 

The solubility of Kelex 100 has been reported to be 4.4 (pH 0.5), 1.4 (pH 1.0), and 1.6 (pH 1.5)ppm, in tests employing 0.5moldm Kelex 100 in Solvesso 150 diluent for the extraction of copper from solutions containing about 30 g dm of metals (Cu, Ni, and Co) [21]. Furthermore, over several months no change in the Kelex concentration was found in pilot plant operations with a 0.5moldm Kelex solution [21]. At higher pH values (up to 9) Kelex solubility has been determined at < 1 ppm in ammonium sulfate solutions up to 300 g dm [22]. It would be expected that the amphoteric nature of Kelex would show increasing solubility at pH values above 7, and lower than about 1, similar to the variation in solubility of... 

Kelex 100, on the other hand, does not contain adjacent OH groups and can be distilled unchanged under vacuum. However, heating pure Kelex 100 at atmospheric pressure results in considerable darkening of the reagent, probably from decomposition at the double bond [28]. However, the reagent appears to withstand pressure reduction to produce metal powders [personal communication from A.W. Ashbrook, 1973]. 

Hartlage, J. A. Kelex 100—a new reagent for copper solvent extraction. Paper presented at Society of Mineral Engineers, AIME Fall Meeting, Salt Lake City, September 1969. 

Another commercial reagent based on quinoline is LIX34, which is a derivative of 8-alkylarylsulfonamidoquinoline. It has good extractant and stripping performance and, unlike Kelex 100, does not protonate easily. However, the cost of production outweighed these advantages. 

Figure 11.9 Effect of metal concentration in the feed and product solution on flux. Membrane, microporous Celgard 2400/30% Kelex 100 in Kermac 470B feed, pH 2.5 product, 100 g/L H2SO4 [9]...

In the examples given in Figures 11.9-11.11 to illustrate coupled transport, the two oxime carriers used for copper were LIX 64N and Kelex 100, which have the structures ... 

Figure 11.13 The effect of replenishing a hollow fiber coupled transport module with fresh complexing agent. Membrane, polysulfone, hollow fiber/Kelex 100 feed, 0.2 % copper, pH 2.5 product, 2% copper, 100 g/L H2S04 [49]...

Zhivkova, S., Dimitrov, K., Kyuchoukov, G. and Boyadzhiev, L. (2004) Separation of zinc and iron by pertraction in rotating film contactor with Kelex 100 as a carrier. Separation and Purification Technology,... 

Kelex 100, HDEHP, or trioctylphosphine oxide in organic solvents... 

Matsumoto M, Shimauchi H, Kondo K, and Nakashio F, Kinetics of copper extraction with Kelex-100 using a hollow fiber membrane extractor, Solvent Extraction and Ion Exchange 1987, 5(2), 301-323. 

U(VI) Kelex 100 pH in the near neutral range 0.1 M HNO3 Recovery fix)m seawater was possible without pretreatment [60,61]... 

Akiba et al. investigated the carrier-mediated transport of uranium (VI) by a liquid membrane of 7-dodecenyl-8-quinolinol (Kelex 100) [60]. The apparent rate constant of uranium transport was not affected significantly with the increase in the carrier concentration and the pH of the feed solution. They had also reported that uranium can be effectively recovered from seawater through the liquid membranes without any preliminary treatment. Compounds analogous to Kelex 100, with long-chain aliphatic linkages, have been used for this study [61]. 

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