Synergistic extraction

In addition to systems of the above type, i.e. involving adduct formation, various other types of synergistic extraction systems are recognised and have been reviewed.4 An example is the synergistic influence of zinc in the extraction and A AS determination of trace cadmium in water.5 

Though TBP and DOSO adducts of Pu(IV) were observed when HTTA was used as the primary extractant, no such adducts were reported with the Pu(IV)-HPMBP system (110, 111). On the other hand, synergism was observed for Pu(IV) extraction with HTTA, HPMBP, and HPBI (with stringent stereochemical requirements) when TOPO was used as the auxiliary ligand (27, 33). Other tetravalent actinide ions such as Th(IV) and Np(IV) have shown similar extraction behavior (29, 30, 34). Some adduct formation constants (I 0 for U(VI) and tetravalent actinide ions are listed in Table 2.4. It is necessary to consider both electronic and steric factors of the ligands to explain the observed trends. 

Synergistic extraction, in the system DEHPA and TOPO, is quite interesting for its ability to extract uranium from high concentrations of phosphoric acid (38). This finds application in the recovery of uranium from dilute phosphoric acid medium in 

Ternary Adduct Formation Constants of Early Actinide Ions with some Beta-Diketones 

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The use of dithizone in combination with various organic bases for synergistic extraction has already been indicated (Section 6.4). 

Synergist Extract Pyrethrin 1 Pyrethrin II Cinerin l Cinerin II... 

Synergistic extraction systems include various new types of interesting interfacial reactions. These systems should be studied more extensively. 

From the fundamental knowledge concerning the interfacial complexation mechanism obtained from the kinetic studies on chelate extraction, ion-association extraction, and synergistic extraction, one can design the interfacial catalysis. The main strategy is to raise the concentration of the reactant or intermediate at the interface. 

Pai, S. A. Lohithakshan, K. V. Mithapara, P. D. Aggarwal, S. K. Thermodynamics of synergistic extraction of americium(III) with HTTA using DHDECMP(bi-functional) and TBP(mono-functional). Radiochim. Acta 1998, 81, 189-193. 

It is the basis of a very sensitive synergistic extraction photometric procedure for trace amounts of... 

Theory Dithizone and 1, 10-phenanthroline (see Section 27.3.3) help in the synergistic extraction of Ni (II) both quantitatively and rapidly over a wide range of pH between 5.5 to 11.0 to give rise to a dark coloured mixed-ligand complex that absorbs at 520 nm. The resulting complex bears the following vital characteristic features, namely ... 

Hi) Effect of ion-pair formation, and (/v) Effect of synergistic extraction... 

A combination of known extractants can increase the net extraction both in degree and kinetics through synergistic extraction. This subject also is poorly explored, though it is of considerable importance to industrial solvent extraction processes. 

Case II Synergistic Extraction of Uranyl Ions by Chelation and Adduct Formation... 

Fig. 4.2 Synergistic extraction Distribution of U(VI) between 0.01 M HNO3 and mixtures of thenoyltrifluoroacetone (TTA) and tributylphosphate (TBP), or tributylphos-phineoxide (TBPO), at constant total molarity ([TTA] ,g plus [TBP] rg or [TBPO] ,g = 0.02 M) in cyclohexane. (From Ref. 2.)...

Phosphates Florida H2SO4 leads to a phosphoric acid solution that contains 50-200 ppm of U Synergistic extraction of U(VI) by HDEHP-TOPO or extraction of U(1V) by diaUcylphosphoric acids mixtures Few % will vary with U price. The phosphate rocks are the second largest potential source of U after sea water... 

Figure 19 Examples of the synergistic extraction of UVI by 0.1 M HDEHP in kerosene with various neutral ligands B from an aqueous phase containing 1.5 M H2SO and 0.04 M UVI...

Otu, E.O. The synergistic extraction of thorium(lV) and uranium(VI) by 2-ethylhexyl phenylphosphonic acid and micelles of dinonylnaphthalene sulphonic acid, Solvent Extr. Ion Exch. 15 (1997) 1-13. 

Batzar, K. Goldberg, D.E. Newman, L.J. Effect of P-diketone structure on the synergistic extraction of uranyl ion by tributylphosphate, J. Inorg. Nucl. Chem. 29 (1967) 1511-1518. 

Patil, S.K. Ramakrishna, V.V. Kartha, P.K.S. Gudi, N.M. Synergistic extraction of plutonium(IV) from nitric acid medium by mixtures of TOPO and HTTA, Sep. Sci. Technol. 15 (1980) 1459-1469. 

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