Solvent extraction column

Determination of trace metals in seawater represents one of the most challenging tasks in chemical analysis because the parts per billion (ppb) or sub-ppb levels of analyte are very susceptible to matrix interference from alkali or alkaline-earth metals and their associated counterions. For instance, the alkali metals tend to affect the atomisation and the ionisation equilibrium process in atomic spectroscopy, and the associated counterions such as the chloride ions might be preferentially adsorbed onto the electrode surface to give some undesirable electrochemical side reactions in voltammetric analysis. Thus, most current methods for seawater analysis employ some kind of analyte preconcentration along with matrix rejection techniques. These preconcentration techniques include coprecipitation, solvent extraction, column adsorption, electrodeposition, and Donnan dialysis. 

Waste water Solvent extraction column clean-up (EPA Method 617) GC/ECD confirmation by GC/MS 0.15 ng/L 89.1 EPA 1992b... 

Groundwater Solvent extraction, column chromatographic cleanup, concentration of extract GC-MS (EPA Method 8250A) 1.5 mg/L (0.43c+1.26)/c x 100 where c is the actual concentration EPA 1994a... 

If multiple solvent extraction operations are a necessity, the chemical engineer usually recommends a less labor-consuming process. A frequently used approach, which can generally be automated, is to build a simple low-cost solvent extraction column (Figure 2), wherein efficient mixing of organic solvent and aqueous layers in a countercurrent flow system elegantly serves the purpose. 

The zirconium tetrachloride product must then be purified before reduction to metal. In particular, hafnium must be removed to less than 100 ppm Hf Zr because of the high neutron absorption cross-section it exhibits, and phosphorus and aluminum must be removed to even lower specifications due to their deleterious metallurgical impact on the final zirconium alloys. The tetrachloride product is first dissolved in water under carefully controlled conditions to produce an acidic ZrOCl2 solution. This solution is complexed with ammonium thiocyanate, and contacted with methyl isobutyl ketone (MIBK) solvent in a series of solvent extraction columns. Advantage is taken of the relative solubilities of Zr, Hf, and Fe thiocyanate complexes to accomplish a high degree of separation of hafnium and iron from the zirconium. 

CFD has also been applied to analyze the flow patterns in a special counter-current solvent extraction column (Angelov et al, 1990). They used a singlephase flow representation and a k- turbulence model to compute the flow patterns in a periodic structure of the column. Validation of the computational results was achieved by applying LDA to obtain experimental data on the velocity profiles. CFD is a very useful tool here because the optimization of the performance of the extraction column from a geometrical point of view can be achieved with relative ease in comparison with a pure empirical strategy. 

A combined electrochemical cell and pulsed solvent extraction column in which one of the electrodes consists of a bed of electrically conducting particles was developed at the U.K. 

Correlations for Estimating fob Purchased Costs for Internals (e.g., Distillation Trays, Absorber Packings, Solvent Extraction Columns, and Others. Referenced to Mid-1968 Dollars with (M S = 273.1). Correlated Using Information from Guthrie [71]... 

Figure 7.7 Calculated separation performance of Bureau of Mines thiocyanate solvent extraction columns for separation of zirconium and hafnium.

The stage holdup time h and separation factor a of a solvent extraction column for uranium enrichment are = 10 s, a = 1.0010. What is the minimum equilibrium time of an ideal cascade fed with natural uranium, stripping to 0.2 w/o and enriching to 3 w/o product Repeat for 90 w/o product. 

The acetone extract of okara fermented with Penicillium expansum Link MK-57 was found to exhibit the insecticidal activity against silkworms. The acetone extract of okara fermented with this strain was purified by solvent extractions, column chromatography, HPLC, and crystallization to yield five active compounds—i.e., two known compounds, communesins A (70) and B (71), and three new ones, communesins D (72), E (73), and F (74) [48]. The structures of the known compounds, 70 and 71, were assigned by comparing their physicochemical properties and spectral data with those reported in the literature [49]. 

Extract with DCM, filtered and concentrated Homogenized sample mixed paraffin or glycerol, water and NaOH, vacuum distilled at low temperature. Distillate extracted on-column or by shaking with solvent and concentrated Solvent extracted, column chromatographic clean-up, extract concentrated Solvent extracted by Soxhlet or sonication, extract subjected to column chromatographic clean-up, concentration of extract... 

Phase-equilibrium calculations were discussed for vapor-liquid equilibria (VLB), liquid-liquid equilibria (LLE), and solid-solid equilibria (SSE). Results from VLE calculations often take the form of K-factors and relative volatilities, especially when thermodynamic calculations serve as intermediate steps in computer-aided process-design programs. In those situations, K-factors are routinely provided to subprograms that size distillation columns and gas-liquid absorbers. Similarly, the distribution coefficients computed for LLE serve as bases for sizing solvent-extraction columns moreover, liquid-liquid distribution coefficients may be helpful in screening candidate solvents for use in an extraction. 

Additives and low molecular weight compounds Solvent extraction -column chromatography 123... 

Figure 8.1.2. (a) Type (2) systems. Countercurrent flow of a gas stream and an absorbent liquid in a vertical column for absorption of a species from the gas countercurrent separation system without recycle or reflux, (b) Countercurrent solvent extraction column lighter liquid introduced at column bottom by dispersing it as droplets as it rises through a continuous heavier liquid, which flows downward through the column. In aqueous-organic extraction systems, usually the aqueous phase is heavier. 

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