Barium sulfate properties

In other applications of CT, orally administered barium sulfate or a water-soluble iodinated CM is used to opacify the GI tract. Xenon, atomic number 54, exhibits similar x-ray absorption properties to those of iodine. It rapidly diffuses across the blood brain barrier after inhalation to saturate different tissues of brain as a function of its lipid solubility. In preliminary investigations (99), xenon gas inhalation prior to brain CT has provided useful information for evaluations of local cerebral blood flow and cerebral tissue abnormalities. Xenon exhibits an anesthetic effect at high concentrations but otherwise is free of physiological effects because of its nonreactive nature. 

These are known as chemically pure (CP) cadmiums. With the development of other uses for cadmium and selenium, costs have risen substantially in recent years. Some cost reduction may be obtained by use of the cadmium Hthopones. These have the same relative shades but have been coprecipitated onto about 60% barium sulfate. The resulting extensions give better money value, if the higher pigment loading can be tolerated, with no loss in properties. 

Radiopaque materials are used to determine the location of aspirated dentures and fragments (205,206). Opacifying additives include barium sulfate, barium fluoride, barium or bismuth glasses, and brominated organic monomers and polymers. The incorporation of these additives into the resin base or tooth can adversely affect physical properties. Radiopaque materials meeting the requirement for ANSI/ADA specifications for denture-base polymer have been described (207). 

Y. B. Zeng and S. B. Fu. The inhibiting property of phosphoric acid esters of rice bran extract for barium sulfate scaling. Oilfield Chem, 15(4) 333-335,365, December 1998. 

V Gallardo, L Zurita, A Ontiveros, JDG Duran. Interfacial properties of barium sulfate suspensions. Implications in their stability. J Pharm Sci 89 1134— 1142, 2000. 

Some properties of the rock used in this study were measured The cation exchange capacity (cec) was determined by the barium sulfate method as described by Mortland and Mellor (33). Surface area was measured by using a Digisorb Meter (Micromeritics Instrument Corporation) through nitrogen adsorption. Estimation of mineral composition and indentification of the rock were performed by X-ray diffraction. 

A number of resinated grades are produced in order to provide higher transparency and to optimize other aspects of pigment properties in application. For reasons connected with process engineering, the resin is typically incorporated as a metal (calcium) resinate. In the past, types of P.R.57 1 additionally contained certain amounts of barium sulfate. 

Scratch resistance depends on the hardness of the added particles. The problem of a lack of this property can be addressed by adding chemically identical particles of different crystal modification and Mohs hardness. The preferred additives are silica, alumina, layered silicates such as kaolin, titania, barium sulfate and calcium carbonate. The latter is only suitable for the DMT process owing to side reaction caused by acidity during the terephthalic acid (TPA) route. 

Rubidium acid salts are usually prepared from rubidium carbonate or hydroxide and the appropriate acid in aqueous solution, followed by precipitation of the crystals or evaporation to dryness. Rubidium sulfate is also prepared by the addition of a hot solution of barium hydroxide to a boiling solution of rubidium alum until all the aluminum is precipitated. The pH of the solution is 7.6 when the reaction is complete. Aluminum hydroxide and barium sulfate are removed by filtration, and rubidium sulfate is obtained by concentration and crystallization from the filtrate. Rubidium aluminum sulfate dodecahydrate [7488-54-2] (alum), RbA SO 12H20, is formed by sulfuric acid leaching of lepidolite ore. Rubidium alum is more soluble than cesium alum and less soluble than the other alkali alums. Fractional crystallization of Rb alum removes K, Na, and Li values, but concentrates the cesium value. Rubidium hydroxide, RbOH, is prepared by the reaction of rubidium sulfate and barium hydroxide in solution. The insoluble barium sulfate is removed by filtration. The solution of rubidium hydroxide can be evaporated partially in pure nickel or silver containers. Rubidium hydroxide is usually supplied as a 50% aqueous solution. Rubidium carbonate, Rb2C03, is readily formed by bubbling carbon dioxide through a solution of rubidium hydroxide, followed by evaporation to dryness in a fluorocarbon container. Other rubidium compounds can be formed in the laboratory by means of anion-exchange techniques. Table 4 lists some properties of common rubidium compounds. 

The refractive index n of ZnS, which determines its scattering properties, is 2.37 and is much greater than that of plastics and binders (n = 1.5-1.6). Spheroidal ZnS particles have their maximum scattering power at a diameter of 294 nm. Barium sulfate does not directly contribute to the light scattering due to its relatively low refractive index (n = 1.64), but acts as an extender, and increases the scattering efficiency of the ZnS. 

In many of its chemical properties, radium is like the elements magnesium, caldum, strontium and barium, and it is placed in group 2, as is consistent with its 6s26pcls2 electron configuraUon. Its sulfate (Ksp — 4.2 a 10-1 ) is even more insoluble in water than barium sulfate, with which it is conveniently coprecipitated, Like barium and other alkaline earth metals, it forms a soluble chloride (X p = 0,4) and bromide, which can also be obtained as dihydrates, Radium also resembles the other group 2 elements in forming an insoluble carbonate and a very slightly soluble lodate (Xsp = 8.8 x 1(T10). 

Significant concentrations of contaminant radium may be submicromolar. Therefore, radiochemical separations are commonly employed that make use of a carrier, a nonradioactive element with chemical properties similar to those of radium. For radium, barium is the element of choice, and radium is coprecipitated from solution with barium sulfate, BaSCH Correction for losses in the precipitation procedure may be made by adding a tracer consisting of an isotope of radium not expected in the sample and noting its recovery at the end of the analytical procedure. The isotope radium- 223 can be used for this purpose. 

Figure 4.3 Doctors illuminate the intestines of a patient with the help of the alkaline earth metal barium. The patient drinks a concoction of barium sulfate that lines the stomach and intestines. Barium s chemical properties allow it to absorb X-rays, highlighting any problem areas.

The length of time that barium will last in the environment following release to air, land, and water depends on the form of barium released. Barium compounds that do not dissolve well in water, such as barium sulfate and barium carbonate, can last a long time in the environment. Barium compounds that dissolve easily in water usually do not last a long time in the environment. Barium that is dissolved in water quickly combines with sulfate or carbonate ions and becomes the longer lasting forms (barium sulfate and barium carbonate). Barium sulfate and barium carbonate are the forms of barium most commonly found in the soil and water. If barium sulfate and barium carbonate are released onto land, they will combine with particles of soil. More information on the chemical and physical properties, use, and environmental fate of barium is found in Chapters 3, 4, and 5. 

X-ray Diffraction Analysis. The inorganic components of paper are the most suitable ones for quantitative X-ray diffraction analysis. Most of these compounds are minerals and are present as fillers, coatings and pigments (often whiteners) which are added to improve the properties of the paper. Examples of compounds commonly added to paper are alumina, aluminum silicate, barium sulfate, calcium carbonate, calcium sulfate, calcium sul-foaluminate, iron oxide, magnesium silicate, silica, titanium dioxide, zinc oxide, and zinc sulfide (28). Some of these, e.g., calcium carbonate and titanium dioxide, may be present in any of... 

FIGURE 8 Reflectance properties of typical white standards in the UV-vis-NIR range. (A) Reflectance of barium sulfate. The measurement was carried out with a PerkinElmer Lambda 9 spectrometer equipped with an integrating sphere, and the reactor cell described in Ref. (Thiede and Melsheimer, 2002). For the background correction one piece of Spectralon was placed at the reference port of the sphere, a second piece was placed inside the reactor cell at the sample port of the sphere. For measurement of the presented spectra, BasS04 was placed in the reactor, while the piece of Spectralon at the reference port remained in position. (B) Reflectance of Spectralon as provided by the manufacturer. 

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