Factors Influencing Solvent Extraction

A number of cardinal factors exert a positive influence on the phenomenon of solvent extraction, namely  

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Spivey, et al. have Investigated various factors such as resin capacity, resin phase volume anion adsorption, etc, that affect the sorption of uranium. Trlvlsonno S. has made a literature survey of factors that Influence the adsorption and elution of uranium by and from strong base anion exchange resins. These are similar to the factors Influencing solvent extraction and Include, other than those already mentioned, uranium concentration, anion concentration, pH, the presence of other metallic Ions and foreign anions, temperature, resin size, porosity, cross-linkage, etc. 

Munson CL, King CJ. Factors influencing solvent selection for extraction of ethanol from aqueous solutions. Ind Eng Chem Process Des Dev 1984 23(1) 109—15. 

The choice of a satisfactory chelating agent for a particular separation should, of course, take all the above factors into account. The critical influence of pH on the solvent extraction of metal chelates is discussed in the following section. 

The separation of solids from liquids forms an important part of almost all front-end and back-end operations in hydrometallurgy. This is due to several reasons, including removal of the gangue or unleached fraction from the leached liquor the need for clarified liquors for ion exchange, solvent extraction, precipitation or other appropriate processing and the post-precipitation or post-crystallization recovery of valuable solids. Solid-liquid separation is influenced by many factors such as the concentration of the suspended solids the particle size distribution the composition the strength and clarity of the leach liquor and the methods of precipitation used. Some important points of the common methods of solid-liquid separation have been dealt with in Chapter 2. 

Enumerate the following four cardinal factors which influence the solvent extraction mostly ... 

Rutin extraction from buckwheat was optimally performed using between 50% and 60% ethanol with a 3-hr maceration (Kreft et al., 1999). Repeating the extraction two times was sufficient to extract most of the rutin. Lie et al. (2000) demonstrated the optimization of influencing factors such as extraction temperatures, extraction times, and solvent concentrations in a conventional extraction of dry powdered material of Hypericum perforatum. Applied extraction conditions caused variations to favor different components in the mixture. Higher extraction efficiency was achieved with moderately polar solvents to extract flavonoids such as rutin, isoquercitrin, and quercetin. The optimum extraction conditions for dry Hypericum perforatum leaf powder were determined as 44% to 69% ethanol in acetone with a 5.3- to 5.9-hr maceration at 55°C. 

Schlosser, S., Sabolova, E., Kertesz, R. and Kubisova, L. (2001) Factors influencing transport through liquid membranes and membrane-based solvent-extraction. Journal of Separation Science, 24, 509. 

Extraction Rates. The design of large-scale solvent extraction vessels must accommodate the rate at which equilibrium is attained between the free miscella flowing past the solid particles and the miscella absorbed within the solids. Attainment of equilibrium may be quite slow, particularly as the oil content of the solid material drops to low levels. Investigations show that the rate at which equilibrium is approached (in effect, the extraction rate) is influenced by many factors, including the intrinsic capacity for diffusion of solvent and oil, which is determined primarily by the viscosities of the two the size, the shape, and the internal structure of the solid particles and, at low oil levels in the solids, the rate at which the solvent dissolves nontriglyceride substances that are soluble but dissolve less readily than the triglycerides. 

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