Separation of Impurities

Aromatic compounds, unsaturated, or higher aliphatic compounds Toluene Yellow, sooty flame 

Lower aliphatic compounds Hexane Yellow, almost nonsmoky flame 

Compounds containing oxygen Ethanol Clear bluish flame 

Polyhalogen compounds Chloroform Generally do not ignite until burner flame applied directly to the substance 

Acid salts or organometaUic compounds Ferrocene Residue 

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Saturations-gefass, n. saturation vessel, saturator, -scheidnngt / (Sugar) purification by carbonation (separation of impurities with the lime when the juice is saturated with carbon dioxide), -schlainm, m. (Sugar) sediment from carbonation. 

The major raw materials used at present for the production of alumina are bauxites, which are found in the following mineral forms gibbsite (Al(OH)3), boehmite (AlO OH), and diaspore (AlO OH). The major impurities are the oxides of iron, silicon, and titanium, and organic compounds, all of which must be removed before alumina is suitable for aluminum production. The process objectives are, therefore, separation of impurities and compound production in the present case. Bauxite is first dried to facilitate grinding, destroy organic matter, and oxidize the associated ferrous minerals to the ferric state. The temperature of drying is not allowed to exceed 150 °C, because at higher temperature a part of the combined water is expelled and the solubility is affected adversely. 

The separation of impurities such as calcium, barium and radium can be effected by the precipitation of their sulfates. In the case of sulfuric acid leaching of uraninite ore, the leach liquor contains radium which is removed if barium chloride is added since barium sulfate acts as a carrier for radium sulfate. 

Figure 1 Separation of impurities A, B, and C from the peak of interest (P) using seven different HPLC systems. Reprinted from [14], copyright 2004, with permission from Elsevier. (For each system the column temperature is 30°C, the detector is UV 254 nm and the gradient is a 60-min gradient from 5% to 95% organic modifier. Ml column 250 X 4.6 mm i.d. 5 pm Kromasil C4, mobile-phase acetonitrile/0.1% trifluoroacetic acid [pH 1.9] M2 column 100X4.6 mm i.d. 5 pm Luna phenyl-hexyl, mobile-phase acetonitrile/0.1% acetic acid adjusted to pH 3.5 with ammonium hydroxide M3 column 100 X 4.6 mm i.d. 5 pm Luna phenyl-hexyl, mobile-phase acetonitrile/10 mM ammonium acetate [pH 7.0] M4 column 100 X 4.6 mm i.d. 5 pm Luna phenyl-hexyl, mobile phase THF/10 mM ammonium acetate adjusted to pH 5.0 with glacial acetic acid M5 column 150 X 4.6 mm i.d. 3 pm Spherisorb ODSl, mobile-phase methanol/10 mM ammonium acetate [pH 7.0] M6 column 150 X 4.6 mm i.d. 5 pm Monitor Cl8, mobile-phase methanol/0.1% acetic acid adjusted to pH 3.5 with ammonium acetate M8 column 100 X 4.6 mm i.d. 4 pm YMC J Sphere ODS H80, mobile-phase acetonitrile/0.1% formic acid [pH 2.1] [M7 is a variation on the M8 gradient and is not shown].)...

Zone melting is a possibly generic approach to IL purification. The solidification of ILs often resulfs in the formation of glass. However, it is possible to determine/choose conditions under which single crystals of ILs with a melting point down to -25°C (but not all) can be grown [39]. Where crystallization is seen, then separation of impurities can be demonstrated. 

Table 8.6 Membrane materials and selectivities for separation of impurities from natural gas...

In the manufacture of trisazo dyes, good yield and purity during final coupling are often obtained only in the presence of pyridine or other bases as coupling accelerators [10], Intermediate isolation and separation of impurities prior to continuation of coupling are also frequently necessary. 

Carnauba wax Initial separation of impurities using a cyclone then bleaching with hydrogen peroxide... 

The applications involved essendally pertain to adjustments of the composition of certain gases, the separation of impurities (add gases H2S and C02)i and the recovery or puriflcation of certain gaseous components (H2 C02,02, natural gas etc). 

E. Van Gyseghem, M. Jimidar, R. Sneyers, D. Redlich, E. Verhoeven, D. Massart, and Y. Vander Heyden, Selection of reversed-phase liquid chromatographic columns with diverse selectivity towards the potential separation of impurities in drugs, /. Chromatogr. A 1042 (2004), 69-80. 

Fig. 2 Separation of impurities from a sample of synthetie human ealcitonin for therapeutie use by CZE. Capillary, bare fused-silica (50 pm X 37 em, 30 em to the deteetor) eleetrolyte solution, 40 mM A, A, A/, A/ -tetramethyl-l,3-butanediamine (TMBD), titrated to pH 6.5 with phosphorie acid applied voltage, 15 kV UV detection at the cathodic end.

There are several reports about the application of the disk monolithic columns for the separation and purification of plasma proteins. " Purification and monitoring of clotting Factor IX (FIX) from human plasma were performed using the ion-exchange monolithic disks. In addition, separation of vitronectin from FIX was possible. A similar system was used for the separation of a complex between clotting Factor VIII and von Willebrand factor (FVIII-vWF). Another application was the monitoring of oti-antitrypsin production. Separation of impurities such as human serum albumin and transferrin was achieved in a few minutes. 

Solvent extraction, or liquid-liquid extraction, is the separation of impurities (solutes) from a liquid solution by contacting it with another immiscible liquid (solvent) in which the impurities have a high affinity. The high affinity driving the separation can be either physical solubility differences or a chemical reaction. The solvent may be a single component liquid (toluene) or a mixture (isopropyl ether/octanol). 

The following methods (listed in alphabetic order) can be used for separation of impurities and degradation products ... 

By immobilizing one of the two unsaturated counterparts, homo-couphng involving fhe supported reactant should be, in principle, avoided, and fhe use of excess of fhe second alkene should guarantee high conversion, along wifh ease of separation of impurities. 

Main substance Separation of impurities and main substance, which forms involatile compound with reagent 11,119... 

The handling of impurities in a VCM plant has been investigated by Dimian et al. (2001) by means of computer simulation. It has been demonstrated that selective chemical conversion of intermediate impurities can be used to prevent their accumulation and the occurrence of snowball effects in the separation units. The separation of impurities can be properly handled by exploiting the interaction effects through recycles. More details are given in the Chapter 17 (Case Study 3). 

Membranes are suitable for bulk separation of impurities from hydrogen. They are not capable of producing high purity hydrogen such as that obtained from PSA adsorption. In addition, a high feed gas pressure is necessary. A pressure drop across the membrane of several hundred pounds per square inch is required to obtain economical recovery. Hydrogen permeates the membrane surface thus, the impurities exit at essentially feed gas pressure and hydrogen leaves the membrane at reduced pressure. 

The experiments performed indicated that silica gel was highly effective in separating impurity number 1 from the main component, while the cyano-modified silica gel was more selective in the separation of impurities number 2 and 3 from the target product. After further optimization work with regard to the most efficient ratio of silica gel/cyano-modified silica gel an amount of 100 g of silica gel and 1250 g of cyano-modified silica gel was chosen to fill the 110 mm I.D. test columns. 

Two or more radioisotopes of the same element that cannot be measured by spectral analysis require integration of effective separation of impurities and radiation detection of the selected distinguishing decay characteristics. To determine the amounts of Sr and °Sr in a sample, for example, interfering radionuclides such as Ra and must be removed only then can the two strontium radioisotopes be distinguished in terms of the radioactive decay of Sr, ingrowth of the daughter, and detector response to beta-particle energies, as discussed in Section 6.4.1. 

For these types of problems, the objective of the optimization needs to be clearly stated. In the case of the separation of impurities or degradation products, one may need to separate all components that are present above a... 

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