Insoluble Glasses

Special Property P2O5 AI2O3 SiOj B2O3 Network Modifiers (or Formers) 

Some zinc phosphate glasses have low transition temperatures and excellent water resistance [19], Fluorophosphate glasses based on AlfPOjlj and LiF possess special optical properties in addition to having good water resistance. Glasses of this kind, based on combinations of other cation metaphosphates and fluorides, have been patented [20]. 

The addition of fluoride ions to phosphate melts generally reduces their viscosity. This is believed to be due to the breaking of P-O-P linkages as a result of formation of P-F terminal linkages (12.64a) [21], 

Radioactive waste can be encapsulated in Pb0/Fe203/P205 glasses which are very resistant to leaching, and are stable to radiation [24-27]. Phosphate glasses are used in radiation dosimetry and they have other biomedical uses [28]. 

Some iron oxide-containing glasses are nearly optically transparent and can be used for heat-absorbing windows. Sulphatophosphate glasses when milled into plastics will act as fire retardants [29]. 

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Conductance Cells The Cell Constant.—The cells for electrolytic conductance measurements are made of highly insoluble glass, such as... 

In parallel with the studies of processes for recovering fissile material from irradiated fuel in the early 1950 s at CRNL, work began on the treatment of the fission product wastes. It was recognized that a safe and permanent method of disposal would be needed once the nuclear power industry became very large. Immobilization of the fission products in a stable and very insoluble glass was chosen as the best approach. 

No compound of potassium with silicon is accurately known but with silicic acid potash forma compounds, which are known as glass. When the silica predominates, we have ordinary hard insoluble glass when the potash is in excess, the compound is called silicate of potash. It is a glassy mass, soluble in water, and the solution has long been known as liquor of flints. (See, hereafter, under the head of Salts, the silicates, including glass and porcelain). 

Explain why immobilizing radioactive wastes in insoluble glasses and then burying them is an unsuitable method for disposal. 

As described in the product insert, TheraSphere consists of insoluble glass microspheres where Yttrium-90 is an integral constituent of the glass. 

Sometimes the crude substance may contain an insoluble impurity, and on cooling the solution it may be difficult to judge how much of the solid matter is merely undissolved impurity and how much is solute which has subsequently crystallised from solution. To avoid this difficulty, the hot solution should be filtered, and should thus always be absolutely clear before cooling is attempted. Therefore filter the hot solution into a clean tube through a very small fluted filter-paper contained in a correspondingly small glass funnel, which should have had its stem cut off as that shown in Fig. 6, p. 12 (and for the same reason). Unless the upper part of the filter is cut awav to reduce its size to a minimum, a large proportion of the solution will remain held mechanically in the pores of the paper itself and only a few drops of clear filtrate will be obtained. 

Add dil. H2SO4 until the solution is acid to litmus. Cool, and scratch the sides of the vessel with a glass rod a white precipitate indicates an aromatic carboxylic acid or uric acid, or a solid phenol insoluble in water (e.g., i- or 2-naphthol). If a precipitate is obtained, filter off through a Buchner funnel, wash with water, recrystallise if necessary and identify. 

If the chemist wants to know whether her final product is bromo-safrole and not just a bunch of unreacted safrole there is a simple little test she can do. Safrole is soluble (will dissolve in) cold concentrated sulfuric acid. But bromosafrole is insoluble in it. So the chemist can take a shot glass full of straight-from-the-bottle 96% H2SO4 and place it in the freezer until it s ice cold. Then she takes it out and drops a few drops of mystery product into it. If the oil dissolves then the stuff is unreacted safrole. If the oil drops to the bottom and does not dissolve it s the goods. 

Lead antimonate [13510-89-9] (Naples yellow), Pb2(Sb0 2> mol wt 993.07, d = 6.58g/cm, is an orange-yeUow powder that is insoluble in water and dilute acids, but very slightly soluble in hydrochloric acid. Lead antimonates are modifiers for ferroelectric lead titanates, pigments in oil-base paints, and colorants for glasses and glazes (see Colorants for ceramics). They are made by the reaction of lead nitrate and potassium antimonate solutions, followed by concentration and crystallization. 

Zinc phosphate, Zn2(P0 2> forms the basis of a group of dental cements. Chromium and zinc phosphates are utilized in some metal-treating appHcations to provide corrosion protection and improved paint adhesion. Cobalt(II) phosphate octahydrate [10294-50-5] Co2(P0 2 8H20, is a lavender-colored substance used as a pigment in certain paints and ceramics. Copper phosphates exhibit bioactivity and are used as insecticides and fungicides. Zinc, lead, and silver phosphates are utilized in the production of specialty glasses. The phosphate salts of heavy metals such as Pb, Cr, and Cu, are extremely water insoluble. 

Sequestration forms the basis for detergent and water-treatment appHcations of polyphosphates. Sequestration of hardness ions by sodium tripolyphosphate used in detergent formulations prevents the precipitation of surfactants by the hardness ions. Sodium polyphosphate glass (SHMP) may be added to water system to prevent the formation of calcium or magnesium scales by reducing the activity of the hardness ions. However, if the ratio of cation to polyphosphate is too high at a given pH, insoluble precipitates such as may result instead of the soluble polyphosphate complexes. The... 

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