Systems, synergistic solvent

Bond, A. H., Dietz, M. L., and Chiarizia, R. (2000) Incorporating Size Selectivity into Synergistic Solvent Extraction A Review of Crown Ether-Containing Systems, Ind. Eng. Chem. Res., 39(10), 3442-3464. 

Barnard, K.R. and Turner, N.L. (2011) The effect of temperature on hydroxyoxime stability in the LIX 63 - Versatic 10 - tributyl phosphate synergistic solvent extraction system under synthetic nickel laterite conditions Hydrometallurgy 109 245-251... 

C.E Baes, Jr, W.J. McDotvell, S.A. Bryan, The Interpretation of Equilibriunz Data from Synergistic Solvent Extraction systems, Soh. Extr. Ion Exch., 5, 1—28 (1987). 

In the simplest cases, the solvent may consist of one specified component, although in fact in a steady-state cyclic process it is highly unlikely that the solvent will ever come back to the initial composition at time zero. Rather, perhaps, one can say that make-up will entail addition of one material only. Again, clearly this need not be a pure compound, but its composition should be consistent. The single solvent offers limited scope for manipulating the system since it alone must meet all process and operational requirements. In other words, it must satisfy all aspects that will lead to an overall viable system. These aspects include selectivity, capacity, solubility, mass transfer, phase separation, costs, among others. The solvent is, therefore, a mixture components. The solvent components are extractant, (ii) diluent, (iii) modifier, and (iv) synergist. 

Preston, J. S. du Preez, A. C. Solvent extraction of nickel from acidic solutions using synergistic mixtures containing pyridinecarboxylate esters. 3. Systems based on arylsulphonic acids. J. Chem. Technol. Biotechnol. 1998, 71, 43-50. 

The study of electrosynthetic reactions is not a new phenomenon. Such reactions have been the study of investigation for more than a century and a half since Faraday first noted the evolution of ethane from the electrolysis of aqueous acetate solutions. This reaction is more well known as the Kolbe electrolysis [51]. Since the report of Kolbe, chemists have had to wait nearly a century until the development, in the 1960 s, of organic solvents with high-dielectric which have been able to vastly increase the scope of systems that could be studied [52]. Added to this more recently is the synergistic effect that ultrasound should be able to offer in the improvement of the expected reactions by virtue of its ability to clean of surfaces, form fresh surfaces and improve mass transport (which may involve different kinetic and thermodynamic requirements)... 

These equations do not provide complete definition of the reactions that may be of significance in particular solvent extraction systems. For example, HTTA can exist as a keto, an enol, and a keto-hydrate species. The metal combines with the enol form, which usually is the dominant one in organic solvents (e.g., K = [HTTA]en i/[HTTA]]jet = 6 in wet benzene). The kinetics of the keto -> enol reaction are not fast although it seems to be catalyzed by the presence of a reagent such as TBP or TOPO. Such reagents react with the enol form in drier solvents but cannot compete with water in wetter ones. HTTA TBP and TBP H2O species also are present in these synergistic systems. However, if extraction into only one solvent (e.g., benzene) is considered, these effects are constant and need not be considered in a simple analysis. 

An enhancement effect exists between NVP and the acrylate components in the cure of these systems. This behavior is interpreted as synergistic effect resulting from a variety of complex interactions between the components and not simply as a solvent effect. 

Watanabe, M., Mirvaliev, R., Tachimori, S. et al. 2004. Selective extraction of americium(III) over macroscopic concentration of lanthanides(III) by synergistic system of TPEN and D2EHPA in 1-octanol. Solvent Extr. Ion Exch. 22 (3) 377-390. 

Cordier, P.Y., Francois, N., Boubals, N., Madic, C., Hudson, M.J., Liljenzin, J.O. 1999. Synergistic systems for the selective extraction of trivalent actinides from mixtures of trivalent actinides and lanthanides. ISEC 99 Conference on Solvent Extraction for the 21st Century, July, Barcelona, Spain. 

Andersson, S., Ekberg, C., Foreman, M.R.S., Hudson, M.J., Liljenzin, J.O., Nilsson, M., Skamemark, G., Saphiu, K. 2003. Extraction behavior of the synergistic system 2,6-bis-(benzoxazolyl)-4-dodecyloxylpyridine and 2-bromodecanoic acid using Am and Eu as radioactive tracers. Solvent Extraction and Ion Exchange 21(5) 621-636. 

Moyer, B.A., McDowell, W.J., Ontko, R.J., Bryan, S.A., Case, G.N. Complexation of strontium in the synergistic extraction system dicyclohexano-18-crown-6, versatic acid, carbon tetrachloride. Solvent Extr. Ion Exch. (1986), 4(1), 83-93. 

The new features are detailed in this review most using diamide as a model system and illustrated with published data on other extractant systems. Figure 7.1 summarizes the structure of the different extractants cited in this chapter. The mixture of extractants as synergistic systems and extractants, such as the N-polydentate ligands BTP (39, 40), BTBP (41, 42), or bis-malonamide (43), will not be treated here. These extractants have low solubility in alkane and are generally used in chlorinated solvent or octanol or diamide/alkane solution to enhance their solubility. 

Iron-Pentacarbonyl. The FeVIII(CO)5 molecule is equally fundamental to organometallic chemistry and electrochemistry, and, like Feu(Cp)2, is a diamagnetic 18-electron system. It exhibits (a) an irreversible two-election oxidation and (b) an irreversible two-electron reduction (Figure 13.1e). In each case Fe(CO)5 has a synergistic effect on (1) the reduction of residual H20 and (2) the oxidation of solvent molecules ... 

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