Charcoal columns

Manufacture. Trichloromethanesulfenyl chloride is made commercially by chlorination of carbon disulfide with the careful exclusion of iron or other metals, which cataly2e the chlorinolysis of the C—S bond to produce carbon tetrachloride. Various catalysts, notably iodine and activated carbon, are effective. The product is purified by fractional distillation to a minimum purity of 95%. Continuous processes have been described wherein carbon disulfide chlorination takes place on a granular charcoal column (59,60). A series of patents describes means for yield improvement by chlorination in the presence of dihinctional carbonyl compounds, phosphonates, phosphonites, phosphites, phosphates, or lead acetate (61). 

Charcoal is generally satisfactorily activated by heating gently to red heat in a crucible or quartz beaker in a muffle furnace, finally allowing to cool under an inert atmosphere in a desiccator. Good commercial activated charcoal is made from wood, e.g. Norit (from Birch wood), Darco and Nuchar. If the cost is important then the cheaper animal charcoal (bone charcoal) can be used. However, this charcoal contains calcium phosphate and other calcium salts and cannot be used with acidic materials. In this case the charcoal is boiled with dilute hydrochloric acid (1 1 by volume) for 2-3h, diluted with distilled water and filtered through a fine grade paper on a Buchner flask, washed with distilled water until the filtrate is almost neutral, and dried first in air then in a vacuum, and activated as above. To improve the porosity, charcoal columns are usually prepared in admixture with diatomaceous earth. 

Purified by Soxhlet extraction with pet ether for 24h, followed by dissolution in acetone MeOH H20 90 5 5(v/v) and recrystn [Politi et al. J Phys Chem%9 2345 1985. Also purified by two recrystns from absolute EtOH, aqueous 95% EtOH, MeOH, isopropanol or a 1 1 mixture of EtOHrisopropanol to remove dodecanol, and dried under vacuum [Ramesh and Labes J Am Chem Soc 109 3228 1987]. Also purified by foaming [see Cockbain and McMullen Trans Faraday 5oc 47 322 1951] or by liquid-liquid extraction [see Harrold J Colloid Sci 15 280 I960]. Dried over silica gel. For DNA work it should be dissolved in excess MeOH passed through an activated charcoal column and evaporated until it crystallises out. 

Charcoal column to remove organics which lead to corrosion and... 

Fig. 9. Indirect electrosynthetic process for the oxidation of anthracene to anthraquinone [10]. The charcoal column serves to remove organics which lead to corrosion and poisoning of the lead dioxide (Pb02) anode...

The method described by Teichman et al. [15] and discussed in section 9.1.1.2 for the determination of chlorinated insecticides and PCBs in soils has also been applied to sediments. The procedure involves adsorption chromatography on alumina and charcoal, elution with increasing fractional amounts of hexane on alumina columns, and with acetonediethyl ether and benzene on charcoal columns. The polychlorobiphenyl and pesticides are then determined by gas chromatography on the separate elutes without interference. 

The conjugated-PCP in the bile(5.7 g) collected from 30 goldfish (av. 110 g) exposed to 0.1 ppm PCP for 48 h was isolated by treating the bile with activated charcoal columns, followed by elution with an acetone-ammonia mixture and finally by passing... 

Bioassay. Toxicity of the materials was measured by the standard mouse bioassay for paralytic shellfish toxins and expressed by mouse unit (MU) as defined by the method (16). For testing the low toxin levels of algal specimens, extracts were treated with a charcoal column prior to injection into mice. 

For some applications, regeneration is not possible, and the material must be discarded. Additional problems include the fact that the charcoal sorbs based on molecular size pollutants with molecular sizes greater than the pores of the charcoal are unaffected. Flow problems and attrition of the carbon particles are other difficulties. Activated charcoal columns are usually pressure vessels due to the large and dynamic pressure drops across the carbon bed. 

Activation of charcoal is generally achieved satisfactorily by heating gently to red heat in a crucible or quartz beaker in a muffle furnace, finally allowing to cool under an inert atmosphere in a desiccator. To improve the porosity, charcoal columns are usually prepared in admixture with diatomaceous earth. 

Preliminary Purification of Lima Bean and Alfalfa. The pH 7 buffer solution was washed once with ethyl acetate, acidified to pH 2 with sulfuric acid, and extracted several times with ethyl acetate. The combined ethyl acetate extracts were evaporated under reduced pressure below 40° C. The residue was dissolved in pH 7 buffer and then added to a charcoal column (10 grams of 1 1 Darco G-60-crushed glass particles). The column was eluted with 95% acetone, the eluate was evaporated to dryness, and the residue was taken up in methanol. 

The active solids from the charcoal column were subjected to a fractional... 

In 1951, Whistler and Durso reported68 the isolation of epimelibiose by partial, acid hydrolysis of the polysaccharide guaran, followed by charcoal-column fractionation of the products. ThA material was obtained in anhydrous crystalline form from a mixture of methyl and butyl alcohols it had m.p. 201°, [a]26D + 120.9° — +124.6° in 36 hr. (c 2, in water). The yield was 2.2% of the weight of guaran used. Epimelibiose has also been produced72" in crystalline form following the ammonia-catalyzed alkaline isomerization of melibiose. 

In the ASAHI KASEI Medical (Tokyo, Japan) system, the plasmapheresis step is performed by a microporous membrane (Plasmaflo) made of a copolymer of ethylene and vinyl alcohol (PEVA), with a maximum pore size of0.3 pm. The extracted plasma flows through an activated charcoal column Hemosorba and an anion-exchange column (copolymer of styrenedivinyl benzene) Plasorba that binds bilirubin and bile acids [28]. Each column contains 350 mL of adsorbent. 

Hemoperfusion differs from hemodialysis in that the blood is passed over a resin or charcoal column. The drug becomes bound to the column and the clean blood returned to the body. Hemoperfusion units have adsorptive surface areas of several thousand square meters while hemodialysis devices have an effective dialysis surface limited to several square meters. Obviously, relatively sophisticated technology is required for these procedures and there is the need to prevent clotting in the circuit, which can produce complications. 

Jans son et al. [52] described a multiresidue method for PCA analysis in biological samples by acetone-hexane and diethylether-hexane extraction, oxidation with sulfuric acid to remove lipid, and isolation of PCAs on SX-3 Biobeads GPC. A combination of silica and activated charcoal column chromatography was then used to isolate other OCs. With diethylhexylphthalate (DEHP) as a retention indicator and (1 1) DCM/hexane as the mobile phase for GPC, PCAs were selectively removed from other persistent OCs by collecting an initial fraction that corresponded to a factor times the retention time of DEHP. All other... 

Table II. Separation of Isotopic Methanes on a Charcoal Column ...

Zachau et al. (1966a) used charcoal columns (Carboraffin C treated with 95% ethanol - 8% sec. octanol, dried and degassed) at 4°C. The oligonucleotides were adsorbed, the column washed with water, and the oligonucleotides eluted with 8% aqueous phenol, pH 7. The phenol was removed with ether extraction. However, in later experiments they preferred dialysis at least for penta- and higher oligonucleotides. 

The kinetics of the reaction have been investigated , and it is therefore possible to determine atomic hydrogen concentrations from the rate at which ortho-H.2 appears in a system initially containing only para-H2. Ortho-para hydrogen ratios may be determined by vapour phase chromatography using charcoal columns , and this technique probably replaces the earlier thermal conductivity measurements (for a description of the latter see ref. 220). The rate coefficients of reaction (23) cannot be fitfed to a simple Arrhenius expression Schulz and LeRoy find that their results can be expressed by... 

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