Extraction behavior

Harrowfield et al. [37-39] have described the structures of several dimethyl sulfoxide adducts of homo bimetallic complexes of rare earth metal cations with p-/e rt-butyl calix[8]arene and i /i-ferrocene derivatives of bridged calix[4]arenes. Ludwing et al. [40] described the solvent extraction behavior of three calixarene-type cyclophanes toward trivalent lanthanides La (Ln = La, Nd, Eu, Er, and Yb). By using p-tert-huty ca-lix[6Jarene hexacarboxylic acid, the lanthanides were extracted from the aqueous phase at pH 2-3.5. The ex-tractability is Nb, Eu > La > Er > Yb. 

We have studied the extractant behavior of a series of compounds containing the carbamoylmethylphosphoryl (CMP) moiety in which the basicity of the phosphoryl group and the steric bulk of the substituent group are varied (10,LL). These studies have led to the development of extractants which have combinations of substituent groups that impart to the resultant molecule improved ability to extract Am(III) from nitric acid and to withstand hydrolytic degradation. At the same time good selectivity of actinides over most fission products and favorable solubility properties on actinide loading are maintained (11). 

This paper describes a comparison of the extraction behavior of selected. actinide(III), (IV), and (VI) ions by the dihexyl-N, N-diethyl analogs of carbamoylmethyl-phosphonate and phosphinate and octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide. 

Crystals of [Tc(tu)6]Cl3 or [TcCl(tu)5]Cl2 are often employed for the synthesis of technetium(III) complexes. However, since the direct reduction of pertechnetate with excess thiourea in a hydrochloric acid solution yields [Tc(tu)6]3+ in high yield [37], direct use of the aqueous solution of the thiourea complex would be preferable for the synthesis of the technetium(III) complex without isolation of the crystals of the thiourea complex. In fact, technetium could be extracted from the aqueous solution of the Tc-thiourea complex with acetylacetone-benzene solution in two steps [38]. More than 95% extraction of technetium was attained using the following procedure [39] First a pertechnetate solution was added to a 0.5 M thiourea solution in 1 M hydrochloric acid. The solution turned red-orange as the Tc(III)-thiourea complex formed. Next, a benzene solution containing a suitable concentration of acetylacetone was added. After the mixture was shaken for a sufficient time (preliminary extraction), the pH of the aqueous phase was adjusted to 4.3 and the aqueous solution was shaken with a freshly prepared acetylacetonebenzene solution (main extraction). The extraction behavior of the technetium complex is shown in Fig. 6. The chemical species extracted into the organic phase seemed to differ from tris(acetylacetonato)technetium(III). Kinetic analysis of the two step extraction mechanism showed that the formation of 4,6-dimethylpyrimidine-... 

Hasegawa, Y. Kobayashi, I. Okuda, A. Solvent-extraction behavior of platinum(TV) and palladium(II) as chlorocomplex acids with trioctylphosphine oxide. Anal. Sci. 1991, 7, 377-381. 

Ohto, K. Yamaga, H. Murakami, E. Inoue, K. Specific extraction behavior of amide derivative of calix-4-arene for silver (I) and gold (III) ions from highly acidic chloride media. Talanta 1997, 44, 1123-1130. 

Since the extraction behavior of pertechnetate is nearly equal to that of perrhenate, the separation of both elements is difficult and often involves reduction of Tc (VII) to lower oxidation states. 

According to Eq. (4.74) Aex increases to the z power of the dissociation constant, A a, for the extractant acid HA. Thus it appears desirable to use stronger acids as extractants, i.e., those with large (or small pATa). Thus factors that affect the dissociaton constant of an acid are of importance for extraction behavior. 

The centrifugal separator of the AKUEVE system is also used for phase separation in the SISAK technique [84]. SISAK is a multistage solvent extraction system that is used for studies of properties of short-lived radionuclides, e.g., the chemical properties of the heaviest elements, and solvent extraction behavior of compounds with exotic chemical states. In a typical SISAK experiment, Fig. 4.34, radionuclides are continuously transported from a production... 

If reprocessing of spent Th fuels is needed in the future, many drawbacks of the Thorex process can be avoided by using A, A -dialkylamides instead of TBP. It is known from studies of Pu(IV)-U(VI) separation with amides that U(VI)-Th(IV) separation in acidic medium is easier than with TBP. The advantages of amides over phosphates could probably be considered more freely for Thorex than for Purex plants because no Thorex plant has been built yet. The extraction behavior of Pa(V) has not been yet investigated but in view of the general chemical properties of the two extractants, smaller distribution ratios are expected with the A, A -dialkyl-amides. 

Extraction and purification of proteins by employing RMs have been extensively studied using model systems (proteins from commercial suppliers) such as cytochrome C, ribonuclease, a-chymotrypsin, etc. However, very few reports are available on the extraction studies of proteins from the real systems of fermentation broths using RMs [ 15,43]. As we know that fermentation broths containing proteins are very much more complicated media compared to model proteins and mixture of model proteins, there is a need to investigate extraction behavior of proteins present in these real systems. 

Visser, A.E., Swatloski, R.R, and Rogers, R.D., pH-dependent partitioning in room temperature ionic liquids provides a link to traditional solvent extraction behavior. Green Chem., 2,1-4, 2000. 

Cocalia, V.A., Jensen, M.P., Holbrey, J.D., Spear, S.K., Stepinski, D.C., Rogers, R.D., Identical extraction behavior and coordination of trivalent or hexavalent f-element cations using ionic liquid and molecular solvents, /. Chem. Soc., Dalton Trans., 11,1966-1971,2005. 

The p-values for over 100 pesticides and related substances were established by studying the extraction behavior of those compounds in a wide range of binary solvent systems. Gas chromatography—based on electron-capture detection—was used to obtain the experimental data. As a result of these studies, Beroza and Bowman reported that ... 

Extraction behavior of highly complex mixtures usually can be known only from experiment. The simplest equipment for that purpose is the separatory funnel, but complex operations can be simulated with proper procedures, for instance, as in Figure 14.3(c). Elaborate automatic laboratory equipment is in use. One of them employs a 10,000-25,000 rpm mixer with a residence time of 0.3-5-Osec, followed by a highly efficient centrifuge and two chromatographs for analysis of the two phases (Lo et al., 1983, pp. 507). 

Figure 14.5. Representation of solvent extraction behavior in terms of certain properties rather than direct compositions [Dunstan et aL, Sci. Pet., 1825-1855 (1938)]. (a) Behavior of a naphthenic distillate of VGC = 0.874 with nitrobenzene at 10°C. The viscosity-gravity constant is low for paraffins and high for naphthenes, (b) Behavior of a kerosene with 95% ethanol at 17°C. The aniline point is low for aromatics and naphthenes and high for paraffins, (c) Behavior of a dewaxed crude oil with liquid propane at 70°F, with composition expressed in terms of specific gravity.

Figure 5. Extraction behavior of phenol, 2-chlorophenol and 3-methyl-4-chlorophenol at different extraction pressures.

Kanellakopulos, B., Konig, C.P. 1983. On the extraction behavior of technetium with respect to the Purex process. Radiochim. Acta 33 169-175. 

Taylor, R.J., Sinkov, S.I., Choppin, G.R., May, I. 2008. Solvent extraction behavior of neptunium(rV) ions between nitric acid and diluted 30 % tri-butyl phosphate in the presence of simple hydroxamic acids. Solvent Extr. Ion Exch. 26 (1) 41-61. 

Pathak P.N., Kumbhare, L.B., Manchanda, V.K. 2001. Structural effects in N,N-dialkyl amides on their extraction behavior toward uranium and thorium. Solvent Extr. Ion Exch. 19 (1) 105-126. 

Narita, H., Yaita, T., Tachimori, S. 1999. Extraction behavior for trivalent lanthanides with amides and EXAFS study of their complexes. In Solvent Extraction for the 21st Century. Proc ISEC 99, Barcelona, Spain, July 11-16, Cox, M., Hidalgo, M. Valiente,... 

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. 

Musikas and co-workers studied extensively the extraction behavior of inorganic acids and U/Pu extraction chemistry with A/,A-dialkyl amides (202-205). Based on the extraction data, they proposed certain dialkyl amides suitable for the reprocessing of irradiated nuclear fuels in nitric acid media. Most of the work reported earlier on amides referred to either aromatic or substituted aliphatic hydrocarbons employed as diluents. However, these diluents are not suitable for commercial-scale reprocessing due to their poor radiation and chemical stability in the presence of nitric acid, as well as their tendency to form a three-phase system. 

U(VI) Th(IV) Solid (tissue paper/oxide) TOPO, TBP, acac, HDEHP, CMPO, etc. Nature of extractant and preheating of tissue paper affected the extraction behavior of uranium (243-245)... 

Ruikar, P.B. Nagar, M.S. Subramanian, M.S. Gupta, K.K. Varadarajan, N. Singh, R.K. Extraction behavior of uranium(VI), plutonium(IV) and some fission products with gamma pre-irradiated n-dodecane solutions of N,N -dihexyl substituted amides, J. Radioanal. Nucl. Chem. 196 (1995) 171-178. 

Mohapatra, P.K. Manchanda, V.K. An unusual extraction behavior of americium(III) and dioxouranium(VI) from picric acid medium using 18-crown-6 as neutral oxodonor, J. Radioanal Nucl. Chem. 241 (1999) 101-105. 

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