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A separatory funnel used for liquid–liquid extraction, as evident by the two immiscible liquids.. Liquid–liquid extraction, also known as solvent extraction and partitioning, is a method to separate compounds or metal complexes, based on their relative solubilities in two different immiscible liquids, usually water (polar) and an organic solvent (non-polar).
Organic solvents are almost always used as a mixture with water for process considerations such as reducing the vapour pressure and lowering the pH in order to also solubilise hemicellulose. Only some small organosolv pulp mills are run today for production of pulp from annual renewable non wood fibre sources like straw, bagasse, etc. [ 8 ]
Acid–base extraction is a subclass of liquid–liquid extractions and involves the separation of chemical species from other acidic or basic compounds. [1] It is typically performed during the work-up step following a chemical synthesis to purify crude compounds [2] and results in the product being largely free of acidic or basic impurities.
Specific extraction methods depend on the soluble characteristics relative to the sorbent material such as concentration, distribution, nature, and size. [1] Leaching can occur naturally seen from plant substances (inorganic and organic), [ 2 ] [ 3 ] solute leaching in soil, [ 4 ] and in the decomposition of organic materials. [ 5 ]
The distribution of a solute between two phases is an equilibrium condition described by partition theory. This is based on exactly how the analyte moves from the initial solvent into the extracting solvent. The term washing may also be used to refer to an extraction in which impurities are extracted from the solvent containing the desired ...
The extraction curve of % recovery against time can be used to elucidate the type of extraction occurring. Figure 4(a) shows a typical diffusion controlled curve. The extraction is initially rapid, until the concentration at the surface drops to zero, and the rate then becomes much slower. The % extracted eventually approaches 100%.
Extractive distillation is defined as distillation in the presence of a miscible, high-boiling, relatively non-volatile component, the solvent, that forms no azeotrope with the other components in the mixture. The method is used for mixtures having a low value of relative volatility, nearing unity. Such mixtures cannot be separated by simple ...
Aqueous biphasic systems (ABS) or aqueous two-phase systems (ATPS) are clean alternatives for traditional organic-water solvent extraction systems.. ABS are formed when either two polymers, one polymer and one kosmotropic salt, or two salts (one chaotropic salt and the other a kosmotropic salt) are mixed at appropriate concentrations or at a particular temperature.