Charcoal Activation Method

Nagarajaiah et al. examined the interaction of each of the ammine complexes such 

The most striking characteristic of the mentioned method is the use of activated charcoal in cold medium. Under such a condition a luteo-type complex may be labilized by charcoal, and then equilibration is established among the possible products through ligand scrambling. In this sense the method for the preparation of mixed amminecyano complexes may be termed charcoal activation method . 

This method was successful in obtaining several stereoisomers of the [Co(CN)2-(R-pn)2] complex . A similar reaction between [Cr(en)3] and CN resulted in the isolation of trans- and ds-[Cr(CN)2(en)2] . Recently, two new complexes trans- and ds-[Co(CN)4(NH3)2] and a known complex [Co(CN)s(NH3)f were prepared from a reaction mixture of [Co(NH3)6](C2H302)3 and KCN in the mole ratio of 1 3.5 These complexes were effectively separated by Sephadex chromatography. Thus, the ammine-cyano series of complexes were completed this is the first example for the complete series of mixed ligand complexes consisting of two kinds of unidentate ligand. 

In 1968, Nishikawa et al. extended the charcoal activation method to obtain the bis(acetylacetonato)dicyano complex, OT-K[Co(CN)2(acac)2], and then prepared a triphenylphosphine-containing complex, [Co(CN)2(acac)(PPh3)2j  

Kashiwabara et al. communicated optical resolution of (2-aminoethyl)-n-butylphenylphosphine and the preparation of the bis(acetylacetonato)colmlt011) complex containing the resolved aminophosphine. The resolved phosphine was allowed to react with tris(acetylacetonato)cobalt(III) in methanol solution in the presence of activated charcoal at room temperature. From the resulting solution a pair of diastereoisomers as shown in Fig. 1.6 was isolated by column chromatography using a SP-Sephadex C-25 ion exchanger and an aqueous solution of Na2[Sb2(rf-tart)2j. 

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Charcoal. Activated coconut charcoal has gained the status as the almost universal solid sorbent. Petroleum-based charcoal is less active, but is also widely used. Charcoal is a very effective sorbent and is generally used for collection of nonpolar organic solvent vapors. It also collects polar organics, but they frequently cannot be recovered. However, many organic substances that are reactive, polar, or oxygenated (e.g., chloroprene, acetic acid, and acetone) have been successfully collected and recovered from charcoal. Substances for which charcoal tube methods have been validated are listed in Table II. 

Most published methods are for analysis of crops and soil residues of the intact acaricides. Extraction has been done by stripping, blender or soxhlet. Extraction solvents have included petroleum ether, benzene, carbon tetrachloride, acetonitrile, diethyl ether, methanol and hexane/acetone. Clean-up steps have em -ployed liquid/liquid partitioning and adsorption on activated charcoal, activated charcoal/Florisil, Florisil, alumina and silica gel. Burke (14) reported that CB is not completely recovered from Florisil. Horn and coworkers (7) found that no clean-up was necessary when analyzing dog urine for CB using a Schecter-Haller procedure. For detection of residues, the colorimetric and UV methods have been replaced by gas chromatographic methods employing microcoulometric or electron capture detectors. 

Defluoridation processes can be classified into four main groups Adsorption methods, in these methods sorbents such as bone charcoal, activated alumina and clay are used in column or batch systems. Ion-exchange methods, these methods require expensive commercial ion-exchange resins. Coprecipitation and... 

No satisfactory method has been found for removing the 3-4% of A-fraction presumably remaining in the Pentasol non-precipitated B-traction. Bates, French and Rundle have suggested that this may be removed by repeated treatment with cotton. Attempts to apply this purification have not been successful. Various grades of cotton, cellulose pulp, charcoal, activated alumina, precipitated aluminum hydroxide, bentonite and fuller s earth have been tested, without any significant improvement in the purity of the B-fraction. It is possible that Bundle s cotton treatment may introduce traces of lipid material (fatty acids or sterols) which mask the iodine adsorption. 

The use of charcoal for purifying whiskey is an old practice. Formerly, the whiskey was percolated through a bed of charcoal— a method still employed in some operations. A more recent procedure is to mix the whiskey with a small dosage of powdered activated carbon for about 1 hour. Usually 0.1 to 0.2% of carbon is sufficient except for whiskies from sour mashes, which may require 0.3 to 0.5%. The carbon is added to the high wine (the distillate from the fermented mash) and after filtration, the whiskey is barreled and handled in the usual manner. 

Standard Practice for Sampling Atmospheres to Collect Organic Compound Vapors (Activated Charcoal Adsorption Method), D3686, in Annual Book of ASTM Standards, Vol. 11.03, Philadelphia, PA, American Society for Testing and Materials 1983... 

The comparatively low tolerance of ruminants to 5-triazines, which has been experimentally established by several authors, has led to loss of cattle that ingested concentrated products on the farm. The mechanism of this peculiar sensitivity has not been elucidated. A successful therapy is based on administering repeated large doses of activated charcoal this method eliminates the herbicide from the enterohepatic circulation before intestinal reabsorption produces toxic tissue levels and eventual death. 

In 1936, SubbaRow and associates (105) reported the preparation of an active product by the elution with 65 per cent ethyl alcohol of an aqueous extract of liver after adsorption on charcoal—a method which they had already used in the isolation of fraction C (104) and one which is quite similar to that developed by Kyer at about the same time (73). At this time, they described an improved method of preparing fraction B, a concentrated but impure material, active in pernicious anemia patients (Table XII) ... 

Ma.nufa.cture. The preparation of sulfuryl chloride is carried out by feeding dry sulfur dioxide and chlorine into a water-cooled glass-lined steel vessel containing a catalyst, eg, activated charcoal. Alternatively, chlorine is passed into Hquefted sulfur dioxide at ca 0°C in the presence of a dissolved catalyst, eg, camphor, a terpene hydrocarbon, an ether, or an ester. The sulfuryl chloride is purified by distillation the commercial product is typically 99 wt % pure, as measured by ASTM distillation method D850. 

Composition and Methods of Manufacture. The vaccine consists of a mixture of purified capsular polysaccharides from 23 pneumococcal types that are responsible for over 90% of the serious pneumococcal disease in the world (47,48). Each of the polysaccharide types is produced separately and treated to remove impurities. The latter is commonly achieved by alcohol fractionation, centrifugation, treatment with cationic detergents, proteolytic en2ymes, nucleases or activated charcoal, diafiltration, and lyophili2ation (49,50). The vaccine contains 25 micrograms of each of the types of polysaccharide and a preservative such as phenol or thimerosal. 

The impressed current protection method is used mainly for the internal protection of large objects and particularly where high initial current densities have to be achieved (e.g., in activated charcoal filter tanks and in uncoated steel tanks). There are basically two types of equipment those with potential control, and those with current control. 

Charcoal Tubes Reference has been made earlier to adsorption, which is the property of some solid materials, such as activated charcoal, to physically retain solvent vapors on their surfaces. In environmental health testing, the adsorbed vapors are removed, generally with a solvent, in a laboratory. The solvent is then analyzed by physical methods (gas chromatography, etc.) to determine the individual compounds whose vapors, such as benzene, were present in the sampled air. Industrial atmospheric samples can be collected in small glass tubes (4 mm ID) packed with two sections of activated charcoal, separated and retained with fiberglass plugs. To obtain an air sample, the sealed ends of the tube are broken off, and air is drawn through the charcoal at the rate of 1 liter per minute by means... 

Filter aids may be applied in one of two ways. The first method involves the use of a precoat filter aid, which can be applied as a thin layer over the filter before the suspension is pumped to the apparatus. A precoat prevents fine suspension particles from becoming so entangled in the filter medium that its resistance becomes exces-sive. In addition it facilitates the removal of filter cake at the end of the filtration cycle. The second application method involves incorporation of a certain amount of the material with the suspension before introducing it to the filter. The addition of filter aids increases the porosity of the sludge, decreases its compressibility, and reduces the resistance of the cake. In some cases the filter aid displays an adsorption action, which results in particle separation of sizes down to 0.1 /i. The adsorption ability of certain filter aids, such as bleached earth and activated charcoals, is manifest by a decoloring of the suspension s liquid phase. This practice is widely used for treating fats and oils. The properties of these additives are determined by the characteristics... 

This step is almost always performed to get rid of the coloured impurities in the fermentation broth. The method is based on the fact that amino adds (esperially the non-aromatic amino acids) do not adsorb onto activated charcoal. Although the treatment is very effective, some of the amino acid is lost during this step. 

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