Barium sulfate precipitation

Barium sulfate [7727-43-7] BaSO, occurs as colorless rhombic crystals, mp 1580 °C (dec) sp gr 4.50 solubihty 0.000285 g/100 g H2O at 30°C and 0.00118 at 100°C. It is soluble in concentrated sulfuric acid, forming an acid sulfate dilution with water reprecipitates barium sulfate. Precipitated BaSO is known as blanc fixe, prepared from the reaction of aqueous solutions of barium sulfide and sodium sulfate. 

Nielsen, A.E. (1957) Nucleation in barium sulfate precipitation. Acta Chem. Scand., 11, 1512-1515. 

Suito, E. and Takiyama, K. (1954) Formation and aging of precipitates. I. Electron microscopic studies of the formation of barium sulfate precipitate. Bull. Chem. Soc. Japan, 27, 121-123. 

Measurements of 226radium are simpler than those for 228radium and are more precise. These measurements are generally made by concentrating the radium from up to a few litres via barium sulfate precipitation followed by thick source a counting or by 222radon extraction following dissolution of barium sulfate [21]. 

Wil Kastning of the Nebraska State Agriculture Laboratory filters barium sulfate precipitates using filtering crucibles and a vacuum system while performing a gravimetric analysis of fertilizers for sulfate content. 

Do not hyphenate two-word modifiers that are chemical names (e.g., amino acid level, barium sulfate precipitate). 

Analytical Methods. Insoluble barium sulfate precipitate, one of the two criteria by which growth of the bacteria was established was determined by standard gravimetric methods. The amount of barium sulfate is directly proportional to the amount of sulfide that has been oxidized by the sulfur bacteria. 

To produce barium sulfate, barium chloride and sodium sulfate can be used. The barium sulfate precipitate can be filtered off, washed with distilled water and dried. The reaction that has occurred is ... 

The gravimetric determination of sulfate can be and is most often used to finish the Eschka and bomb washing methods. The most serious concern is that the barium sulfate precipitated may be extremely fine and difficult to filter. This can be overcome by adding the barium chloride (BaCE) rapidly to the hot solution and stirring the mixture vigorously to obtain a barium sulfate (BaS04) precipitate,... 

L of the acidified acetone-water solution was sufficient to elute the A-4696 activity from the carbon column. The eluate containing the A-4696 activity as treated with a saturated barium hydroxide solution, in order to form a precipitate of barium sulfate, thus removing the sulfate ions from the solution. The mixture was filtered and the barium sulfate precipitate was discarded. The filtrate containing the A-4696 activity was concentrated under vacuum to dryness. The resulting residue comprising the A-4696 activity amounted to approximately 80.0 g. 

Critical sizes characteristic of different substances vary from less than ten to several hundred molecules. The earliest measurements were made by Ostwald (01), who found lO-10 g. to be the limiting mass of sodium chlorate in initiating crystallization from water solution. Volmer and Flood (V8) have shown that the critical nucleus in water vapor condensation is about 80 molecules. Extensive studies of barium sulfate precipitation (C4, L2) indicate that in this system the critical nucleus is no more than the unit cell, consisting of four sulfate and four barium ions. 

In studying barium sulfate precipitation, Nielsen (N4) found that the number of crystals formed depends upon the method of cleaning the glass vessel. Steam-washing the glass vessel reduced the number of barium sulfate nuclei from 2000 to 100 per mm . He concluded that for this system nucleation is primarily catalytic rather than homogeneous. 

Fiq. 18. Fraction of barium sulfate precipitated as a function of time. After Nielsen (N5). 

Barium sulfate precipitation has been reported to be controlled initially by nucleation reaction and, finally, by growth reaction. The growth kinetics was represented by the equation ... 

Microwave laboratory ovens are currently quite popular. Where applicable, these greatly shorten drying cycles. For example, slurry samples that require 12 to 16 hours for drying in a conventional oven are reported to be dried within 5 to 6 minutes in a microwave oven. The time needed to dry silver chloride, calcium oxalate, and barium sulfate precipitates for gravimetric analysis is also shortened significantly. ... 

The amount of hydrochloric acid 50 mL of 1 +5 hydrochloric acid [sp gr 1.16, 32% weight by weight (w/w) as per Indian Standard (IS) of hydrochloric acid] is 1.68N for a 0.5-g test sample of gypsum is too high for any purpose except the quick dissolution of gypsum and other impurities such as carbonate and so forth. This high acidity of the resulting solution before and after barium sulfate precipitation is very likely to introduce errors that affect the results. Reduction of final acidity is therefore necessary for accurate determination of sulfate. 

Old solutions of barium chloride or fresh solutions filtered through fine filter paper are reported to be more effective than the fresh solutions in promoting the formation of large crystals of barium sulfate precipitate 4.SI. For the purpose of rapid filtering and for avoiding transfer of barium sulfate precipitate and ignition of filter paper, the use and type of filtering crucibles should be specified. 

The determination of sulfur trioxide by barium sulfate precipitation is beset with potential errors at every step of the procedure. The details of the procedure must be clear and strictly followed for accurate results. Therefore, in the light of this discussion, the following recommendations are submitted for revision of the ASTM C 471. 

Lithopone is a mixture of 30% zinc sulfide and 70% barium sulfate, precipitated simultaneously. It is used mainly in cheaper white or coloured compounds as a whitening agent [3]. 

Likewise, with respect to the example of silver chloride or barium sulfate precipitation from respective solutions, ionic symbols in model drawings are more appropriate than formal reaction equations. One could first name and sketch the ions of the starting solutions ahead of the precipitation reaction, and could mark them with (aq) symbols. Only after carrying out the precipitation could one consider the type of solid matter and set the symbols for the related solid matter and the remaining solution (see Fig. 5.23). 

Hydrogen Peroxide (H2O2). Hydrogen peroxide can be prepared by the reaction of barium peroxide and sulfuric acid (see equation 13). As barium sulfate precipitates out, hydrogen peroxide is easily separated. 

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