Aqueous extraction vessel

The extraction vessel outlet valve can be controlled either manually from the control unit or automatically by the phase boundary detector unit. The operation of this detector is based on the difference in refractive index between the organic and aqueous phases, and has been described elsewhere [34]. 

Aqueous samples were extracted for phenol and 4-chlorophenol using pure carbon dioxide in a specially designed phase separator apparatus (111). The extraction efficiency for these phenols was reported to be over 85%, with a RSD of 8% for eight samples. Additional liquid sample extractions have been investigated for the extraction of phenol from a 6M sulfuric acid solution as well as the extraction of the components of commercial soft drinks and orange juice (112-113). In all cases, specifically designed extraction vessels were utilized. 

The feasibility of extracting substituted phenols from an aqueous solution with supercritical CO2 is reported A special extraction vessel was used in order to overcome the mechanical difficulty in retaining the liquid matrix in the extraction vessel. Solid phase trapping was utilized with a diol silica bonded phase. Methanol was used to rinse the trap. Below 300 atm extraction recovery paralleled CO2 pressure at fixed temperature. Phenol was least extractable while, 2,4-dichlorophenol yielded the greatest percent recovery. Above 300 atm extraction yield declined with pressure. It is theorized that at high CO2 density there is less mixing with the aqueous phase because of increased fluid-fluid interaction. 

That shown in Fig. 2.93, when fitted with flask and condenser, is suitable for extractions of about 10 ml of solution. The condensed solvent drops through the funnel and thence down through the solution and escapes via the side-arm sealed into the bottom of the extractor thimble. When assembling the apparatus it is advisable to pour a few millimetres of the extracting solvent into the thimble before pouring in the liquid to be extracted in this way contamination of the solvent in the flask by a carry-over of solution to be extracted is minimised. The apparatus shown in Fig. 2.94, when fitted with a flask and condenser, is suitable for the extraction of about 50 ml of aqueous solution the baffle discs improve the dispersion of solvent into droplets. Some of the solvent should be placed in the extraction vessel first, then the baffle plates and finally the aqueous solution further addition of solvent to prevent the passage of aqueous solution down the... 

Solid samples mixed with water or methanol an aliquot of aqueous extract or a portion of methanol extract spiked into water and measured into the purging vessel subjected to purge and trap concentration and analyzed as above. 

One extraction process used industrially on a large scale is the purification of sodium hydroxide for use in the manufacture of rayon. The sodium hydroxide produced by electrolysis typically contains 1% sodium chloride and 0.1% sodium chlorate as impurities. If a concentrated aqueous solution of sodium hydroxide is extracted with liquid ammonia, the NaCl and NaClOs are partitioned into the ammonia phase in preference over the aqueous phase. The heavier aqueous phase is added to the top of an extraction vessel filled with ammonia, and equilibrium is reached as droplets of it settle through the ammonia phase to the bottom. This procedure reduces impurity concentrations in the sodium hydroxide solution to about 0.08% NaCl and 0.0002% NaClOj. 

When the culture is carried out in the fermentation vessel, 145 L. of culture filtrate are obtained after culture for 12 days. This culture filtrate is made alkaline with a 2 N sodium hydroxide solution and then extracted 5 times at a pH of 7.4 and 3 times at a pH value of 10, each time with 200 liters of ethyl acetate. The combined ethyl acetate extracts are then concentrated to 50 liters and the alkaloids removed from the concentrate with the aid of an aqueous tartaric acid solution. These aqueous extracts are made alkaline and again extracted at pH values of 7.4 and 10 with ethyl acetate. After washing until neutral with a little water, the solutions are evaporated to dryness. 

Experimental details.583 A pentane solution (200 300 ml) of 50 (200 him) and the sensitizer 52 (5 mM) was irradiated in a quartz vessel with a low-pressure mercury lamp (30 W) through a Vycor sleeve (>250 nm) (Figure 3.9) under an argon atmosphere at —88 °C for 72 h. After irradiation, the product was extracted from the solution with aqueous silver nitrate at 0°C and the combined aqueous extracts were washed with pentane and then added dropwise into concentrated ammonia solution to liberate 51, which was subsequently extracted with pentane. 

Galey FD, Beasley VR, Schaeffer D. Effect of an aqueous extract of black walnut (Juglans nigra) on isolated equine digital vessels. Am J Vet Res 51 83-88, 1990. 

The efficient extraction of saturated aqueous solutions of PAHs with organic solvents is usually not a problem. Problems are associated, however, with the transfer of aliquots of the saturated solution to extraction vessels. Adsorptive losses of PAHs on the surfaces of transfer tools (pipets, beakers, etc.) are possible. These errors can be eliminated by rinsing the transfer tools with the extracting solvent or by employing methods that do not involve transfer steps. 

Figure 4.23 Illustrates another alternative for the separation of both phases once the batch liquid-liquid extraction has been finished. Formerly conceived for solid-liquid extractions, this complex mechanical assembly [20] consists of two automatic burettes for addition of the two phases, the extractor —moveable in various fashions— and a vertically moving paddie stirrer. The extraction vessel rotates at a high speed, which promotes phase separation, as shown in the figure. The lighter phase creeps up the walls and passes to an upper receptacle —the separation is facilitated by adding more aqueous phase. Once separation Is complete, an aspiration probe withdraws the organic phase. Finally, a mechanical system turns the vessel over for cleaning.

Documented effects Experiments have shown that preparations of this species has very low toxicity and even after long periods of use show no side effects. It possesses cardiotonic, hemostatic, styptic, diuretic, and bacteriocidic properties and raises arterial pressure and causes narrowing of the blood vessels. In small doses preparations of this plants work as a tonic, and in larger doses, depress the central nervous system (Khalmatov et al. 1984). In some countries the herb is used to treat skin cancer and as a prophylactic after removal of a tumor (Akopov 1990). An aqueous extract of the plant exhibited anti-tumor activity in vitro (Abuharfeil et al. 2(K)0). 

If an aqueous extraction is not sufficient, it may be necessary to consider a wet chemical digestion. Open digestions can be carried out relatively simply in heat resistant vessels on a hotplate. Digestions under pressure require special vessels and the necessary safety precautions must be observed. 

The pH of the aqueous phase from the first HTTA extraction was then adjusted to 1. When adjusting it is important not to exceed pH 2, because a too high pH will cause an irreversible sorption of trivalent actinides on the walls of the extraction vessel. Am and Cm were then extracted into 2.5 ml 1 M HDEHP in kerosene. The extraction was repeated with 2.5 ml of fresh HDEHP solution to increase the yield. The contact time was 60 s. Then Am and Cm were back-extracted into 1 ml 7 M HNO3. The acid was diluted to 1 M HNO3, and used for a-spectrometry. 

Thermospray nebulizers can be used to extract SVOCs from aqueous samples. When several thermospray probes simultaneously deliver solvent and sample into a cooled extraction vessel an efficient extraction can occur because of the increased exposure of the phases. Farrel and Pacey built a device called a thermospray liquid-liquid extractor (TSLLE). Using the TSLLE and methylene chloride they evaluated aqueous mixtures of SVOCs and obtained recoveries ranging from 80 to 100% during a single, 1-h cycle. The aqueous sample was dehvered at 4 or 5 mL/min, and the methylene chloride was delivered at 2 or 3 mL/min. through heated capillaries into the chilled extraction vessel. The system was vented above a chilled condenser, and a stopcock at the bottom of the vessel allowed for phase separation of the methylene chloride after extraction (72). 

Batch Extractions. In nearly all commercial scale operations, a continuous extraction process, either mixer-settlers or colunm units, would be used. However, batch extraction experiments are useful for assessing overall feasibility and for optimizing the many process variables such as emulsion formulation and volume ratios of the internal, membrane, and external phases. Consequently, the most common experiment in this study was the batch extraction. In these experiments, 500 ml of a selenium solution (1 mg/L) were prepared in the extraction vessel, either in the presence or absence of other competing anions. The prepared emulsion (50 ml) was added and the mixture was stirred at a speed of 150 rpm. In this manner the emulsion drops were uniformly dispersed in the external phase while extraction proceeded. Samples of the external aqueous phase were taken at appropriate intervals and the concentrations of Se(IV), Se(VI), and sulfate were determined. 

The aqueous extract and phenolic fractions of mistletoe exhibited in vitro vasodilating effect on the coronary blood vessels, rat aortic rings, and perfused heart model. The effect may be mediated through modulation of nitric oxide production. Lignans are believed to... 

For biocompatibility testing using cytotoxicity (ISO 10993-5), the samples are either tested directly, as in an agar overlay test, or are extracted, as in minimum essential medium elution. Extraction is a process in which the test material is typically subdivided, placed in an extraction vessel, and covered with the exttaction vehicle. Polar and nonpolar extraction vehicles are used separately. Examples of polar extraction vehicles are water, cell culture media, and physiological saline, that is, 0.9 % aqueous NaCl solution, which is usually the preferred polar vehicle for biological assays. Examples of nonpolar vehicles include cotton seed oil and sesame seed oil. 

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