Iron back-extraction

A solution of both ammonium pyrrolidinedithiocarbamate and diethyldithio-carbamate has been used for eomplexing iron (Co, Ni, Cu, Zn, Cd, Pb) in sea water. The metal carbamate complexes are extracted from 500 ml of sea water at ca. pH 5 into 30 ml of Freon TF (l,l,2-trichloro-l,2,2-trifluoroethane) and back-extracted into 10 ml of 0.3 M nitric acid. The main advantage of this method is the transfer of the metals to a solution in which their concentrations do not change with time 70). 

Fluoride can be determined by means of an iron(iii) thiocyanato complex extracted into isobutylketone. Iron is extracted back into the aqueous phase with the fluoride sample solution. The atomic absorption signal of iron is directly proportional to the concentration of fluoride (0.5-6 ju,g F ml ). EDTA can be determined by a similar technique. Copper is first extracted as the hydroxyquinolinato complex into isobutylketone, and then extracted back into the aqueous solution with the EDTA sample solution. In these methods the analyte anion must form a more stable complex compound with the metal ion than the ligand used for the first solvent extraction. These kind of... 

Sb is isolated from manganese, iron and interfering elements by extraction with MIBK from 3 m H2SOz with 0.01 m iodide. After back-extraction with 0.4 m hydrochloric acid, excess iodide is removed by oxidation with H2O2 and extraction of the liberated iodine with chloroform. Any H2O2 still... 

In iron deficiency where iron is unavailable for incorporation into heme in the developing reticulocytes or where incorporation is inhibited as in lead toxicity, protoporphyrin IX accumulates in the red cells. This can be measured by extraction into ethyl acetate-acetic acid and then back-extracted into HCl. After neutralization, an ether extraction followed by differential extraction into HCl allows separation of protoporphyrin and coproporphyrin. 

X The activity In this fraction Is extracted from acidic solution by benzene. Is not back-extracted by water, or by aqueous solutions of potassium Iodide, potassium lodate. Iron (II), or sulfurous acid, but Is back-extracted by aqueous sodium hydroxide. 

One method which gave a purification of iodine-131 from a 16-day-old solu-tion of 10 fissions had the following steps (224). Iodide, iodate, or periodate carrier and sodium chlorate were added to the sample which contained only inorganic substances (but no gold) and no reducing agents. The solution was made 6-10 in hydrochloric acid in order to produce iodine monochloride (yellow-green solution). The monochloride was extracted into butyl acetate and then back-extracted into water as iodide by means of sulfurous acid. Iodide was oxidized to elemental iodine with iron(III) chloride in dilute sulfuric acid and the iodine extracted into toluene. The element was back-extracted into water as iodide by sulfurous acid and palladium(II) iodide was precipitated. 

While the liquid-liquid extraction of inorganic elements as coordination complexes with thiocyanate ions can be traced back to Skey (1867), the extraction from hydrochloric acid into ether of iron(III) (J. W. Rothe, 1892) or gallium (E. H. Swift, 1924) depends on the formation of solvated acido complexes derived from HMC14 extractions of metal complexes from nitric, thio-cyanic, hydrofluoric, hydrochloric and hydrobromic acids were studied exhaustively by Bock and his collaborators (1942—1956).6... 

Love and Pearson (6) have described a model meat system in which bovine muscle was ground and extracted with distilled, deionized water at 4°C until it was devoid of color, indicating the removal of all meat pigments, i.e., myoglobin and hemoglobin. Other water-soluble components would also be partially or completely extracted by this procedure. The remaining extracted muscle was then used as a model system to which purified myoglobin, ferrous iron and ferric iron were added back to ascertain their role in WOF. 

Paracelsus abandoned all this witchcraft and superstition. He started the search for the potent drugs which the alchemist was to prepare or purify. Even the many herbs and extracts in common medical use were placed secondary to the value of these chemicals. There were many who gave ear to his instructions They went back to their laboratories, threw away the crucibles filled with the strange concoctions that would not change to gold, and sought medicines to relieve human suffering. Paracelsus himself showed the way. He experimented in his laboratory, and introduced into medicine salves made from the salts of mercury. He was the first to use tincture of opium, named by him laudanum, in the treatment of disease. The present pharmacopoeia includes much that Paracelsus employed —lead compounds, iron and zinc salts, arsenic preparations for skin diseases, milk of sulfur, blue vitriol, and other chemicals. 

Price [67] has reviewed the application of atomic absorption to a variety of plating solutions. Iron, lead and zinc are reported as the main impurities in cyanide copper-plating baths which may contain up to 200gl 1 of copper sulphate a twenty-fold dilution of the sample for trace determination is recommended. Nickel baths may contain 60 gl 1 of nickel and it may be necessary to monitor copper, zinc, iron, lead, chromium, calcium and magnesium at the ppm level. The standard addition method is probably best for such an application. Zinc has been extracted with trioctylamine-hydrochloride when present in the range 0.03—10pgml-1 in a nickel plating solution [68]. The zinc was re-extracted back into 1M nitric acid for... 

Technical Observations Primuline fusions are handled in vessels heated in oil baths and having condensers supplied with warm water so that the p-toluidine which sublimes does not stop up the tubes. The hydrogen sulfide is collected in sodium hydroxide and used in reductions. Originally, the hydrogen sulfide was burned to heat the vessels, a procedure which is irrational in every respect and a nuisance for the neighborhood. The alcohol extraction is carried out in iron vessels having a fine sieve and filter at the bottom, and the alcohol is distilled back into the vessel just as in a Soxhlet extractor. After the alcohol is evaporated from the extract, the residue is heated to 240° until no more p-toluidine is being recovered. 

The hexane-extracted particles that still retained one Q per P700 retained 81 % of the NADP -reduction activity ofthe unextracted control. In contrast, particles extracted with hexane-0.3% methanol had all the OQ removed and the NADP -reduction activity was completely lost. The NADP -reduction activity of the hexane/methanol-extracted particles could be reactivated by readdition of exogenous but only when the hexane extract was also added back. Exogenous OQ alone, even at a rather high concentration, could not reactivate NADP photoreduction and the hexane extract alone was also not effective, presumably because of its low Q content. The nature ofthe component in the hexane extract that contributes to reconstitution is as yet unknown. As the hexane extract contains OQ,chlorophylls,carotenoids,lipidsand other nonpolar molecules, some critical component is probably needed to ensure the correct membrane structure for binding ferredoxin and/or Fd-NADP -reductase. This conclusion is supported by the fact that activity of prior terminal acceptors such as the iron-sulfur centers do not require the hexane extract. 

The minerals from which the metals are extracted, existed for millions of years in the earth s crust and are the most stable form of the metal. A considerable amount of energy is required to convert this mineral into the metal. Once this pure metal comes into contact with the natural environment such as sea-water or soils, the metal slowly converts back to its original starting material. Iron, for example, is obtained from the mineral, haematite, an oxide of iron. Once the pure iron comes into contact with water and air (oxygen), it slowly converts back to the oxide. This is called corrosion and the product is familiar to everyone as red rust. Nearly all metals will corrode in natural environments although the rates of corrosion will vary from metal to metal and alloy to alloy. In addition, the rates of corrosion will vary from one natural environment to another. Iron will corrode at approximately 50 pun per year in freshwater but at 120 pm per year in seawater. The reason for this is due to the difference in chemical composition between freshwater and seawater. The latter contains salt (sodium chloride) and this is very deleterious to the corrosion behaviour of the metal. Silver artefacts may be excavated after several hundred years buried in soils with only minimal amounts of corrosion. Those recovered from marine sites after a similar period of burial, have completely corroded and have reverted back to 100% mineral. This is entirely due to the presence of chlorides in seawater. 

The kerosene fraction is now subjected to a second solvent extraction. Addition of iron(II) sulfamate, Fe(NH2S03)2, and shaking of the kerosene fraction with water, results in the formation of plutonium(III) nitrate which is partitioned into the aqueous layer. [U02][N03]2 resists reduction, is com-plexed by TBP and remains in the organic layer. Separation of the two solvent fractions thus separates the uranium and plutonium salts repeated extractions result in a highly efficient separation. The extraction of [U02][N03]2 from kerosene back into an aqueous phase can be achieved by adding nitric acid under these conditions, the uranium-TBP complex dissociates and [U02][N03]2 returns to the aqueous layer. 

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