Sulfuric acid digestion

Opa.nte. There are two methods used at various plants in Russia for loparite concentrate processing (12). The chlorination technique is carried out using gaseous chlorine at 800°C in the presence of carbon. The volatile chlorides are then separated from the calcium—sodium—rare-earth fused chloride, and the resultant cake dissolved in water. Alternatively, sulfuric acid digestion may be carried out using 85% sulfuric acid at 150—200°C in the presence of ammonium sulfate. The ensuing product is leached with water, while the double sulfates of the rare earths remain in the residue. The titanium, tantalum, and niobium sulfates transfer into the solution. The residue is converted to rare-earth carbonate, and then dissolved into nitric acid. 

The most universal method for sample destmction before SPh metal determination (Ee, Mo, A1 and etc.) is the sulfur acid digestion at high temperature by Kjeldall. It can be enforced by microwave decomposition in the microwave oven. 

Evans et al. [98] has described a method for the determination of total copper, iron, manganese and zinc in various plant materials. Organic matter is destroyed by wet oxidation and measurement is made directly upon the sulfuric acid digests by flame atomic absorption spectrophotometry. In the measurement, direct interferences from the inorganic species found in plant... 

Antimony. Antimony dust has been analyzed colorimetrically by formation of a Rhodamine-B complex, 565 nm (Table I ). Both P CAM 173 (5) and S-2 (11) provide AAS methods for antimony. Whereas the former method recommends 5 1 nitric sulfuric acid digestion, the latter uses only 2-ml nitric acid at 140°C followed by 2 ml of 6 N hydrochloric acid. Either the nitric/sulfuric acids (10% and 5% v/v) or a 10% tartaric acid (11) matrix may be used for the analyte solution. Although the normal analytical wavelength is 217.6 nm, when 10,000 ppm Pb or 1000 ppm Ca are present in the final solution, then the 231.2 nm analtyical line should be used. A new method for antimony has been developed by NI0SH and will be published in volume four of the methods manual. 

Test Solution Transfer 134 mg of sample to a 250-mL beaker, and cautiously add 10 mL of 11IV nitric acid and 10 mL of 18 A sulfuric acid. Digest with the aid of heat in a well-ventilated hood until brown fumes cease to evolve. Cautiously add an additional 10 mL of 11 A nitric acid, and continue heating until no more fumes evolve. Cool, transfer to a 200-mL volumetric flask, and dilute to volume with water. 

Generally speaking, there are two processes for the extraction of rare earths from monazite. One of the processes involves sulfuric acid digestion and this is illustrated in Fig. 1.3. 

In perchloric acid and nitric acid/sulfuric acid digestions, salts precipitate out as the digestion reduces the volume of solution. Danger exists... 

Sulfuric acid digestion either alone or in conjunction With nitric acid has been used to dissolve organic materials without... 

Difficulties in the Kjeldahl determination of nitrogen (c), center chiefly on the problem of digestion. Variable factors known to influence the completeness (and speed) of conversion of protein nitrogen into ammonia by sulfuric acid digestion include the following sources of error ... 

A concentrated nitric acid - perchloric acid - sulfuric acid digest of the polymer is analysed at 193.7 nm by atomic absorption spectrometry. The procedure is calibrated against standards of arsenic free acrylic fibre and pure arsenic trioxide. 

To the flask used for the reagent blank determination introduce the same amount of catalyst mixture, sulfuric acid and glucose. Suitable catalysts and length of sulfuric acid digestion time for the digestion of various types of nitrogen compounds and polymers are shown in Table 2.7. 

Ammonium Salts.—Ammonium salts may be estimated by the Ivjeldahl procedure without requiring sulfuric acid digestion. 

Sulfuric Acid Digestion (Japan) (Double Alkali) u... 

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