Zinc fractionation

Agbenin J.O. Zinc fractions and solubility in a tropical semi-arid soil under long-term cultivation. Bio Fertil Soils 2003 37 83-89. 

LeClaire, J.P., Change A.C., Levesque C.S, Sposito G. Trace metal chemistry in arid-zone field soils amended with sewage sludge. IV Correlations between zinc uptake and extracted soil zinc fractions. Soil Sci Soc Am J 1984 48 509-513. 

Mandal L.N., Mandal B., Zinc fractions in soils in relation to zinc nutrition of lowland rice. Soil Sci. 1986 142 141-148. 

Murthy A.S.P., Zinc fractions in wetland rice soils and their availability to rice. Soil Sci 1982 133 150-154. 

Prasad B., Mehta A.K., Singh M.K. Zinc fractions and availability of applied zinc in calcareous soil treated with organic matter. J Indian Soc Soil Sci 1990 38 248-253. 

Budd, P.D., Lythgoe, P., McGill, R.A.R., Pollard, A.M. and Scaife, B. (1999). Zinc fractionation in liquid brass (Cu/Zn) alloy potential environmental and archaeological applications. In Geoarchaeology Exploration, Environments, Resources, ed. Pollard, A.M., Special Publication 165, Geological Society, London, pp. 147-153. 

Figure 14. Comparison of measured and predicted zinc fractions, x, in (Cdi.KZnK)S alloy films.

ISO (1983) Sludge and Sediment. Digestion using aqua regia for subsequent determination of acid soluble portion of soil zinc fractions, DIN 38414, Part 7, 4 pp. 

Faure, H., Favier, A., Tripier, M. and Arnaud, J. (1990) Determination of major zinc fractions in human serum by ultraliltration. Biol. Trace Elem. Res., 24, 25-29. 

A zinc protein containing 82 to 117 Mg- of zinc per gram of protein was obtained reproducibly from leukocytes by extraction with phosphate buffer for a total period of 12 to 24 hours, pH 7.2 at 4° C., and m = 0.01. In this manner, a soluble fraction comprising 81.1% of zinc of leukocytes and 79.6 % of protein of leukocytes could be obtained. The remaining 18.9 % of leukocyte protein were insoluble under the conditions of extraction. This insoluble zinc fraction has not been investigated beyond establishing it as distinctly different from the soluble zinc protein. Zinc was not associated with fractions of nucleic acids (Hoch and Vallee, 1952). 

Accumulation of heavy metals by several organisms has been shown to be associated with the production of special proteins. The internal organs of marine organisms accumulate not only cadmium but also copper and zinc Fractionation of metal-binding proteins of squid liver by gel permeation chromatography revealed... 

Rgure 3 Sequential extraction scheme for various soil zinc fractions. (From Penreen Z et al. (1994) Redistribution of zinc from sewage-sludge applied to a range of contrasting soils. Science of the Total Environment 55 161-171.)... 

Pure pyridine may be prepared from technical coal-tar pyridine in the following manner. The technical pyridine is first dried over solid sodium hydroxide, distilled through an efficient fractionating column, and the fraction, b.p. 114 116° collected. Four hundred ml. of the redistilled p)rridine are added to a reagent prepared by dissolving 340 g. of anhydrous zinc chloride in a mixture of 210 ml. of concentrated hydrochloric acid and 1 litre of absolute ethyl alcohol. A crystalline precipitate of an addition compound (probable composition 2C5H5N,ZnCl2,HCl ) separates and some heat is evolved. When cold, this is collected by suction filtration and washed with a little absolute ethyl alcohol. The yield is about 680 g. It is recrystaUised from absolute ethyl alcohol to a constant m.p. (151-8°). The base is liberated by the addition of excess of concentrated... 

After the butyl chloride fraction has been collected, change the receiver and continue the distillation untU the zinc chloride commences to crystallise. Allow to cool and stopper the flask. The anhydrous zinc chloride thus obtained may be used in another preparation and recovered repeatedly. This results in considerable economy when the preparation is conducted by a large number of students. 

Reflux a mixture of 68 g. of anhydrous zinc chloride (e.g., sticks), 40 ml. (47 -5 g.) of concentrated hydrochloric acid and 18-5 g. (23 ml.) of sec.-butyl alcohol (b.p. 99-100°) in the apparatus of Fig. 777, 25, 1 for 2 hours. Distil oflF the crude chloride untU the temperature rises to 100°. Separate the upper layer of the distillate, wash it successively with water, 5 per cent, sodium hydroxide solution and water dry with anhydrous calcium chloride. Distil through a short column or from a Claisen flask with fractionating side arm, and collect the fraction of b.p. 67-70° some high boiling point material remains in the flask. Redistil and collect the pure cc. butyl chloride at 67-69°. The yield is 15 g. 

The experimental details for mono-M-propylanillne are as follows. Reflux a mixture of 230 g. of aniline and 123 g. of n-propyl bromide for 8-10 hours. Allow to cool, render the mixture alkafine, and add a solution of 150 g. of zinc chloride in 150 g. of water. Cool the mixture and stir after 12 hours, filter at the pump and drain well. Extract the thick paste several times with boiling light petroleum, b.p. 60-80° (it is best to use a Soxhlet apparatus), wash the combined extracts successively with water and dilute ammonia solution, and then dry over anhydrous potassium carbonate or anhydrous magnesium sulphate. Remove the solvent on a water bath, and distil the residue from a Claisen flask with fractionating side arm (well lagged). Collect the n-propyl-aniline at 218-220° the yield is 80 g. Treat the pasty solid zincichloride with an excess of. sodium hydroxide solution and steam distil 130 g. of pure aniline are recovered. 

Isobutyl alcohol [78-83-1] forms a substantial fraction of the butanols produced by higher alcohol synthesis over modified copper—zinc oxide-based catalysts. Conceivably, separation of this alcohol and dehydration affords an alternative route to isobutjiene [115-11 -7] for methyl /-butyl ether [1624-04-4] (MTBE) production. MTBE is a rapidly growing constituent of reformulated gasoline, but its growth is likely to be limited by available suppHes of isobutylene. Thus higher alcohol synthesis provides a process capable of supplying all of the raw materials required for manufacture of this key fuel oxygenate (24) (see Ethers). 

Volatilization. In this simplest separation process, the impurity or the base metal is removed as a gas. Lead containing small amounts of zinc is refined by batch vacuum distillation of the zinc. Most of the zinc produced by smelting processes contains lead and cadmium. Cmde zinc is refined by a two-step fractional distillation. In the first column, zinc and cadmium are volatilized from the lead residue, and in the second column cadmium is removed from the zinc (see Zinc and zinc alloys). 

Zinc. The 2—3 g of zinc in the human body are widely distributed in every tissue and tissue duid (90—92). About 90 wt % is in muscle and bone unusually high concentrations are in the choroid of the eye and in the prostate gland (93). Almost all of the zinc in the blood is associated with carbonic anhydrase in the erythrocytes (94). Zinc is concentrated in nucleic acids (90), and found in the nuclear, mitochondrial, and supernatant fractions of all cells. 

Butyl slurry at 25—35 wt % mbber continuously overflows from the reactor through a transferline to an agitated flash dmm operating at 140—160 kPa (1.4—1.6 atm) and 55—70°C. Steam and hot water are mixed with the slurry in a nozzle as it enters the dmm to vaporize methyl chloride and unreacted monomers that pass overhead to a recovery system. The vapor stream is compressed, dried over alumina, and fractionated to yield a recycle stream of methyl chloride and isobutylene. Pure methyl chloride is recovered for the coinitiator (AlCl ) preparation. In the flash dmm, the polymer agglomerates as a coarse cmmb in water. Metal stearate, eg, aluminum, calcium, or zinc stearate, is added to control the cmmb size. Other additives, such as antioxidants, can also be introduced at this point. The polymer cmmb at 8—12 wt % in water flows from the flash dmm to a stripping vessel operated under high vacuum to... 

Overflow at the rate of 2700 m (713,000 gal) per day from a zinc-concentrate thickener is treated by ion flotation, precipitate flotation, and untrafine-particle flotation [Nagahama, Can. Min. Metall. Bull., 67, 79 (1974)]. In precipitate flotation only the surface of the particles need be coated with collector. Therefore, in principle less collector is required than for the equivalent removal of ions by foam fractionation or ion flotation. 

The procedures as outlined are applicable to both the aliphatic and aromatic series. They are superior to the common interchange method in that they avoid the fractional distillation which is very troublesome in the aliphatic series. They have been used in numerous instances and can be adapted to give mixed anli3"drides. Benzoic anhydride has been obtained, by closely related procedures, from benzoic acid and benzoyl chloride by heating under reduced pressure or in the presence of zinc chloride. 

Benzylamine [I00-46-9J M 107.2, b 178 /742mm, 185 /768mm, d 0.981, n 1.5392, pK 9.33. Dried with NaOH or KOH, then distd under N2, through a column packed with glass helices, taking the middle fraction. Has also been distd from zinc dust under reduced pressure. 

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