Extraction organic solutes from water, apparatus

Figure 7.13. Apparatus for extracting organic solutes from water. Apparatus for extracting organic solutes from finished drinking water samples. (A) standard garden hose coupling, (B) Teflon washer, (C) 1/2 inch...

Figure L Apparatus for extracting organic solutes from water. A, pure inert gas pressure source B, cap C, 2-L reservoir D, polytetrafluoroethylene stopcock F, 24/40 F, 1.0-cm i.d. X 37-cm long glass tube packed with 13 cm of resin G, silanized glass wool plug.

The solvent extraction of metal-chelate complexes for trace analysis of water samples has been briefly reviewed (473). Concentration factors of less than 1000 are to be expected because of the need to handle reasonable quantities of organic solvent. However, since not all of the organic solvent sample is used in the analysis, this results in a less than optimal use of the system. An excellent batch-extraction apparatus recently has been described (474) for the extraction of organic substances from water. Concentration factors of more than 10,000 were easily obtained if organic volumes of 100 /w, or less, which were used to extract 1 liter of solution, could be fully analyzed (eg., by AAS). A useful system has been described (475) which combines three chelating agents (dithizone, 8-hydroxyquinoline, and acetylacetone) and quantitatively collects Al, Be, Cd, Co, Cu, Fe, Pb, Ni, Ag, and Zn in one extraction at a pH of 6. 

Extraction Apparatus.—Very often an organic substance is so much more soluble in water than in ether and other solvents that shaking with a solvent even when repeated is ineffective. In such cases an apparatus for continuous extraction of solutions is used it should not be wanting in any organic laboratory. The apparatus of Schacherl (Fig. 25), which can be constructed from simple laboratory materials, indicates the principle involved. Still more convenient is the apparatus shown in Fig. 26. It likewise can be constructed in all dimensions from easily obtainable materials. 

Methylnitramine is highly soluble in water, and therefore, must be extracted with an organic solvent (see figure 051). To perform the extraction, vigorously shake the water solution of methylnitramine (obtained in step 2) with 180 milliliters of methylene chloride for several minutes, and then drain-off the bottom methylene chloride layer. Then, add 180 milliliters of methylene chloride to the upper water layer and shake the mixture vigorously for several minutes. Then drain-off the bottom methylene chloride layer. Finally, add 180 milliliters of methylene chloride to the upper water layer, and shake the mixture vigorously for several minutes. Then drain-off the bottom methylene chloride layer. Now, combine the three drained-off methylene chloride layers, and then place the methylene chloride into a distillation apparatus, and carefully distill at 40 Celsius until diy solid remains. If using a rotary evaporator, evaporate-off the methylene chloride under low vacuum. When dry solid remains, remove the heat source, and allow the dry product to cool to room temperature. Then collect the crystalline product from the distillation flask. 

The use of multipass zone-refining apparatus for preconcentration of trace components from water has not been reported, although the concentration of trace flavor components from a solvent extract has been described (J93). It is obvious that the low-temperature preconcentration of organic solutes is desirable if thermal decomposition or reactions are to be avoided. Nevertheless, the use of freezing to concentrate inorganic solutes is worthy of further study, especially if it is possible to use an internal standard to improve upon the reliability of the method to establish a concentration factor for the solutes. 

When a product is very soluble in water, it is often difficult to extract using the techniques described in Sections 12.4 12.7 because of an unfavorable distribution coefficient. In this case, you need to extract the aqueous solution numerous times with fresh batches of an immiscible organic solvent to remove the desired product from water. A less labor-intensive technique involves the use of a continuous liquid-liquid extraction apparatus. One type of extractor, used with solvents that are less dense than water, is shown in Figure 12.15. Diethyl ether is usually the solvent of choice. 

The initial halogenated polymeric materials were obtained from the polyvinyl chloride-polyvinylidene chloride, PVC-PVDC (Rovil fiber) and chlorinated polyvinyl chloride, PVC. Dehydrochlorination was performed in the presence of a base solution in a polar organic solvent (dimethylsulfoxide, acetone or tetrahydro-furane). The products were filtered and extracted with water in a Soxhlet apparatus until all chloride ions were removed. Thermal treatment was performed in a tubular furnace in CO flow at 10 cm min". ... 

After the addition of the reactants is complete, the reaction is allowed to stir for an additional 30 min while the solution warms to room temperature. The reaction mixture is then transferred to a separatory funnel. The viscous organic bottom layer is separated from the aqueous layer and is dissolved in 200 mL of ether. The reaction vessel is washed with 100 mL of ether, and this ether portion is used to extract further the aqueous layer. The ether layers are combined, dried over magnesium sulfate, and filtered, and the solvent is removed under reduced pressure. The viscous oil is allowed to crystallize in an ice bath (0°C). The crystals are collected on a Buchner funnel, washed with 500 mL of water, and dried in a vacuum desiccator at 0.5 mm for 48 hr. 80.8 g (93%) of white crystalline bis(2,2,2-trichloroethyl) hydrazodicarboxylate (mp 85-89°C) is obtained. This material is sufficiently pure for the next preparation. However, further purification can be achieved using an Abderhalden drying apparatus (refluxing 95% EtOH for 12 hr at 0.05 mm MgS04 desiccant). Material purified in this way melted at 96.5-97.5°C (Notes 4 and 5). 

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