Extraction amines

Nickel and Cobalt. Often present with copper in sulfuric acid leach Hquors are nickel [7440-02-0] and cobalt [7440-48-4]. Extraction using an organophosphoric acid such as D2EHPA at a moderate (3 to 4) pH can readily take out the nickel and cobalt together, leaving the copper in the aqueous phase, but the cobalt—nickel separation is more difficult (274). In the case of chloride leach Hquors, separation of cobalt from nickel is inherently simpler because cobalt, unlike nickel, has a strong tendency to form anionic chloro-complexes. Thus cobalt can be separated by amine extractants, provided the chloride content of the aqueous phase is carefully controUed. A successhil example of this approach is the Falcon-bridge process developed in Norway (274). 

Rummey et al. [223] searched replacements for the pyrrolidine present in their DPP-IV inhibitor searching a 10,000-molecule subset of small primary aliphatic amines extracted from the available chemical directory and visually inspected the top 500 of them. Four were selected for testing and two of them were novel hits. 

Tertiary Amine Extraction. Part II. Contaminant Ions. Report ORNL-3244 (1962). 

Baybarz, R. D., Boyd Weaver and H. B. Kinser Separation of Transuranium Elements from Rare Earths by Tertiary Amine Extraction. Trans. Amer. Nucl. Soc. 5, 17 (1962). 

AMEX [Amine extraction] A process for the solvent extraction of uranium from sulfuric acid solutions using an amine extractant ... 

Tramex [Transuranic metal (or amine) extraction] A process for separating transuranic elements from fission products by solvent extraction from chloride solutions into a tertiary amine solution. Developed at Oak Ridge National Laboratory, TN, for processing irradiated plutonium. 

Amine-epoxy resin systems, 10 443 Amine equivalent weight (AEW), 10 399 Amine ethoxylates, 24 150-151 Amine extractants, 10 791 Amine functional curing agents,... 

Among the tertiary amines extraction coefficients decrease with decreasing basicity. Quaternary ammoniiun salts dissolved in inert solvents ensure efficient extraction not only from acid but also from neutral and alkaline solutions. 

Amine extraction is used also in another important industrial process, the extraction of uranium from sulphuric acid leached ores, which uses trilauryl amine (TLA). In that case, the extraction reaction is... 

Four types of organic amines exist, as shown in Table 4.8 primary amines RNHj, secondary R2NH2, tertiary RsNH, and quaternary R4N (Appendix D). The hydrocarbon chain R is usually of length Cg-Cu, commonly a straight aliphatic chain, but branched chains and aromatic parts also occur. In general the amines extract metal complexes in the order tertiary > secondary > primary. Only long-chain tertiary and—to a smaller extent—quarternary amines are used in industrial extraction, because of their suitable physical properties trioctylam-ine (TOA, 8 carbons per chain) and trilauryl amine (TLA, 12 carbons per chain) are the most frequently used. For simplicity we abbreviate all amines by RN, and their salts by RNH L . 

Properties of the feed solution and the substance to be extracted will decrease the number of extractants that may be applicable. For example, in the extraction of metals, if no anionic metal species are present in the feed solution, there is little point in considering anionic (amine) extractants. On the other hand, if anionic metal species are present, then the amine type best suited to the extraction of the anionic species can be selected, knowing... 

Unlike the amine extractants, this compound does not protonate easily and provides excellent selectivity over those metals and metalloids that exist as chloroanions in this medium. Extraction of the latter species becomes significant only above 8 mol dm chloride, as protonation becomes significant. This extractant [Acorga CLX 50], which contains 50% of the active ingredient, has been proposed for an integrated leach, extraction, electrowinning circuit (Cuprex process) [19]. 

The hydrogen sulfide and ammonia can be removed by amine extraction and acid washes respectively. Hydrotreating also removes metals from the feed that would otherwise poison the reforming and cracking catalysts. 

Several analytical techniques including capillary electrophoresis, thin layer chromatography (TLC), GC, lEC, and HPLC, have been proposed for the determination of biogenic amines in various foods. Among these, RP-HPLC is considered the most suitable one. HPLC methods used for amine determination usually involve two steps amine extraction from the matrix and analytical determination. Depending on the complexity of food matrix and the selectivity of the final analytical determination, a further purification step may be necessary prior to the analytical determination. To ensure adequate sensitivity, a derivatization step is generally required before injection [282]. 

As an alternative to RP columns some authors used cation-exchange columns. Salazar et al. [301] used an Alkion column (4x 150mm) heated at 40°C to separate OPA derivate of biogenic amines extracted from complete feeds and animal tissues, while Saccani et al. [302] used an lonPac CS17 column and a gradient elution of methanesulfonic acid to separate biogenic amines in meat products. 

Amine extraction of penicillins has been examined in a pilot scale extractor and its performance has been analyzed through suitable mathematical models 117-19]. Extraction efficiency as high as 90% was achieved under suitable conditions. The procedure for selection of volume ratios of the aqueous to organic phase and concentration ratio of carrier (Amberlite LA-2) to penicillin-G at a desired degree of extraction and enrichment has recently been described [20]. Ion-pair extraction of penicillin-V and phenoxy acetic acid with Amberlite LA-2 hydrochloride and tetrabutyl ammonium hydrogen sulfate can be effective in... 

The existence of the anionic species Hs PbCfe and Hs PbCls2-has previously been established by paper chromatography (3, 4), ion exchange (5, 6, 7), and amine extraction techniques (8). 

Owing to the inadequacy of the mathematical model available for analysis of the amine extraction system (7), accurate values of the stability constants could not be evaluated for the Hs Pbn1-" system in the presence of NaCl. However, using the values of stability constants obtained by Bertazzi for the system (C2H5)3PbCln1 n in LiCl at 8.0 m (10), viz. 0 = 3.5, 02 = 1.0, 0s = 0.1, the neutral species Hs PbCl0 (n = 1) is seen to be dominant. Therefore a simple solvent extraction would be expected to remove a certain amount of triethyl lead from solution. As shown in Table II, this is seen to be so. However,... 

The ammonium sulfate contained in the raffinate is treated with lime to produce ammonia for recycle, and the extracted nickel and cobalt are transferred to a chloride medium (for subsequent separation by amine extractants, as described in Section 63.3.2.4) by stripping with 25% hydrochloric acid solution ... 

Secondary amine extractants are used for the recovery of zinc from liquors obtained by the leaching of pyrite cinders at the Metalquimica del Nervion plant in Bilbao, Spain,69 and at the Quimigal plant near Lisbon, Portugal.91 Traces of other metals that also form chloro anions, such as copper, cadmium and iron(III), are also extracted, and both plants use a second extraction cycle with D2EHPA to further purify the zinc solution prior to electrowinning. 

Molybdenum can also be recovered economically from some uranium leach liquors, particularly those of the USA. When uranium is stripped from amine extractants by solutions of sodium chloride, any molybdenum present remains in the organic phase, and can be subsequently recovered by being stripped into a solution of sodium carbonate. A process has been operated in which the strip liquor is acidified to a pH value of 4.5 and the molybdenum is reextracted into a solution of quaternary amine chloride in kerosene.218 The extracted metal is stripped into a solution containing sodium hydroxide and sodium chloride to produce liquors containing 30-40 g of molybdenum per litre, from which calcium molybdate can be precipitated by the addition of calcium chloride. 

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