Element extraction

The optimum conditions of heavy metals extraction from ordinary chernozem in different solvents are selected both at determination of the mobile forms of elements, and at an estimation of their gross contents. It is established, that the stage of elements extraction in the greater measure depends on time of action and intensity of ultrasonic, nature of selected solvents and determinated elements. It is shown, that for all type of soils the time of low frequency ultrasonic action does not exceed 10 minutes, and the intensity ranges in an interval of 3-4 W/cm. ... 

One possibility for increasing the minimum porosity needed to generate disequilibria involves control of element extraction by solid-state diffusion (diffusion control models). If solid diffusion slows the rate that an incompatible element is transported to the melt-mineral interface, then the element will behave as if it has a higher partition coefficient than its equilibrium partition coefficient. This in turn would allow higher melt porosities to achieve the same amount of disequilibria as in pure equilibrium models. Iwamori (1992, 1993) presented a model of this process applicable to all elements that suggested that diffusion control would be important for all elements having diffusivities less than... 

The protocol involving NaOAc-HOAc at pH 5 was first proposed and used by Jackson (1958) to remove carbonates from calcareous soils to analyze soil cation exchange characteristics (Grossman and Millet, 1961). Other researchers used HOAc for the extraction of metals from sediments and soils (Nissenbaum, 1972 Mclaren and Crawford, 1973). Tessier et al. (1979) first used the NaOAc-HOAc solution at pH 5 to dissolve the carbonate fraction from sediments. Since then, the NaOAc-HOAc buffer has been widely used as a specific extractant for the carbonate phase in various media (Tessier et al., 1979 Hickey and Kittrick, 1984 Rapin et al., 1986 Mahan et al., 1987 Han et al., 1992 Clevenger, 1990 Banin et al., 1990). Despite its widespread use, this step is not free from difficulties, and further optimization is required in its application. Questions arise with regard to this step in the elemental extraction from noncalcareous soils, the dissolution capacity and dissolution rates imposed by the buffer at various pHs, and the possibility that different carbonate minerals may require different extraction protocols (Grossman and Millet, 1961 Tessier et al., 1979). 

Table 4.2. Dissolution of some major elements extracted by NaOAc-HOAc solutions at various pHs after removing the exchangeable fraction3... 

The contents of trace elements extracted by the buffer solutions depend upon the solution s acid capacity in dissolving carbonate from soils. Trace elements dissolved by the buffer solution increased with decreasing pH of the buffer solution (Table 4.3). Release of trace elements by the buffer solutions at pH 6.0 was much smaller from calcareous soils with more than 30% of CaCC>3. The dissolution of trace elements by the buffers paralleled with the dissolution of Ca and Mg. The correlation coefficients between Ca and trace elements were as follows Cd (0.92), Pb (0.87), Zn (0.90), Ni (0.90), Cr (0.91), V (0.54) and Co (0.70) and between Mg and trace elements were Cd (0.88), Pb (0.80), Zn (0.79), Ni (0.87), Cr (0.58), V (0.69) and Co (0.80), (all with n = 32). 

Element Extraction Stripping Element Extraction Stripping... 

For a discussion on the nature of the extractants, see Chapter 4 Trace element extractants. ... 

Dreesen, D. R., Gladney, E. S., Owens, J. W., Perkins, B. L., Wienke, C. L. Wangen, L. E. 1977. Comparison of levels of trace elements extracted from fly ash and levels found in effluent waters from a coal fired power plant. Environmental Science and Technology, 10, 1017-1019. 

Notes on the four elements extracted from Agrippa, fos. 138-9. ... 

Single element extraction. b Competitive extraction of six lanthanides. 

Prokopchuk, Ju.Z., Logunov, M.V., Trukhanov, S.Ja. Method of strontium and rare-earth elements extraction. Pat RU 2027671. 

Griepink, B. (1993) Some considerations with regard to the quality of results of analysis of trace element extractable contents in soil and sediment. Int.f. Environ. Anal. Chem., 51, 123. 

Trace Element Removal During Physical Cleaning. Comnercial coal cleaning processes employ physical means for beneficiation and are aimed at removing ash forming minerals and sulfur, although removal of the mineral matter also results in reduced levels of some trace elements. Trace element extraction efficiencies for various physical cleaning processes have been reported. 

Trace element extraction efficiencies for a given cleaning process are highly variable between coals. 

It is turned into a fixed earth, and is called Coagulation and Incineration, Division of the Elements, Extraction and Quintessence. Then the body becomes ghostly, light, white, and dry. It is called Sublimation, Incineration, Solution. Then the refuse becomes sublimated, so that the Olitet may be obtained. It is also called the White Death, Understanding, Putrefaction, Disintegration, Cooking, etc. 

The transuranic elements extracted from seawater or sediments are further purified such that ... 

The structure and behavior of lanthanides and actinides in ILs has recently been summarized in detail by Binnemans and the reader is referred to this excellent review for more details [71]. Among others, it has been pointed out that solvation of the metal ions by the IL components is a major issue in f-element coordination chemistry [71, 79, 218, 219], Understanding the solvation is also a key to understanding f-element extraction processes. Among others, theoretical studies suggest that Ln3+ (Ln = La, Eu, Yb) are surrounded by six PF6 anions in Bmim-PF6 and by 11-13 imidazolium ions in the second ionic sphere. The same authors also suggest that free lanthanide cations, that is, cations without a solvation shell, are poorly soluble in Bmim-PF6 [149, 152, 220-223], They also report that, while [LnCls]3 complexes are unstable in the gas phase, they can be stabilized by solvation in ILs. 

Table 1 summarises the concentrations of trace elements extracted with chloroform from oil shale samples of the two... 

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