Aluminosilicates soluble

In some modern laundry formulations water hardness-promoting ions are bound to aluminosilicates. However, binding of hardness-promoting ions can only take place if these ions are solved in water. Because aluminosilicates or zeoliths are not soluble in water by themselves they are not able to solve insoluble salts of fatty acids already present in incrustations of fibers. For a suf-... 

The potassium carbonate is soluble and washes away, but the aluminosilicate remains as the clay. Cements are obtained when aluminosilicates are roasted with limestone and other minerals and then allowed to solidify (see Section 14.10). 

Clearance to pulmonary lymph nodes will occur at a fractional rate of 0.0001 per day. Dissolution of the deposited particles and absorption of cerium into the systemic circulation will occur at rates that are between the extremes represented by CeCh in CsCl particles and Ce oxide or Ce in fused aluminosilicate particles as given by the functions included in Figure 9. These rates should not be expected to be constant over the entire clearance period and will depend upon the overall composition of the bulk aerosol particles, which indude particle size, amount of stable lanthanide present, acidity, and the solubility of other components of the particles. The accuracy of predicting respiratory tract clearance and internal organ uptake of radiocerium will depend heavily upon adequate determination of the particle solubility characteristics. 

The aqueous chemistry of aluminum(III) above pH 6 differs from that of silicates in that the only important species, other than solid Al(OH)3 at pH 5-8, is Al(OH)4, which, although isoelectronic with Si(OH)4, shows no tendency to catenate. On the other hand, below pH 5 Alm, unlike the poorly soluble Si(OH)4, is freely soluble as Al3+(aq) [actually Al(OH2)63+, Section 13.2], while at intermediate pH hydrolytic A1 species, including the ion Ali304(0H)24(0H2)127+ referred to above, predominate in solution. However, Al(OH)4 units can readily insert themselves into silicate anion species in solution. The result is usually the prompt precipitation of an aluminosilicate gel (a typical zeolite precursor), although over some limited Al, Si, and OH- concentration ranges quite high concentrations of dissolved aluminosilicates can be maintained over many months.9... 

Griffith7 chronicled in lively fashion the growth and sudden demise of an extraordinary project of the Monsanto Co. to make phosphate fibers as substitutes for the much maligned asbestoses. The object was to make materials with most of the desirable properties of asbestos, but that would hydrolyze slowly in, say, the alveoli of the lungs to form a soluble and biologically beneficial product (phosphate ions), so avoiding the tendency of insoluble aluminosilicate fibers to remain indefinitely in biological material with the attendant risk of cancer. 

That Al3+ is the main toxic agent in many acidified lakes is supported by observations of improved fish survival rates when the silica content of the water is increased, as dissolved silica can form either soluble or insoluble aluminosilicates (see Section 7.6). Mobilized aluminum has also been linked to forest damage, since, in sufficient concentration, it is directly toxic to roots of spruce trees and many other plants. 

Many cements used today are composites of Portland cement and industrial waste materials that can enter into the hydration reactions and contribute to the strength of the hardened product. These substances include pulverized fuel ash (PFA) from burning of pulverized coal in thermal power stations, crushed blast-furnace slag (Section 17.7), and natural or artificial pozzolanas—that is, volcanic ash and similar finely particulate siliceous or aluminosilicate materials that can react with the Ca(OH)2 in Portland cement to form hydrated calcium silicates and aluminates. As noted earlier, the solubility of Ca(OH)2 is such that the pH of pore water in Portland cements will be about 12.7, at which the Si-O-Si or Si-O-Al links in the solid pozzolanas will be attacked slowly by OH- to form discrete silicate and aluminate ions and thence hydrated calcium silicate or aluminate gels. 

Alkali leach methods axe exemplified by the Bayer process for the preparation of pure a-A C for electrolysis (Section 17.5) from the mineral bauxite. Bauxite consists mainly of a-AlO(OH) (diaspore) and/or 7-A10(0H) (boehmite), the difference between these being essentially that the oxygen atoms form hep and ccp arrays, respectively. The chief contaminants are silica, some clay minerals, and iron(III) oxides/hydroxides, which impart a red-brown color to the mineral. Aluminum (III) is much more soluble than iron(III) or aluminosilicates in alkali, so that it can be leached out with aqueous NaOH (initially 10-15 mol L 1) at 165 °C under approximately 0.6 MPa pressure, leaving a red mud of iron (and other transition metal) oxides/hydroxides and aluminosilicates ... 

The Liquid Phase. The liquid phase consisted of a solution of Al-(OH)4 , Si02(0H)22 , Na+, and OH ions, whose concentrations (determined by Raman spectroscopy) did not change significantly during induction and crystallization. No evidence was found for the existence of any soluble aluminosilicate anions. 

Aluminum Solute Species and Solubility. The qualitative importance of metal-ion hydrolysis in determining the solution chemistry of aluminum is generally recognized. Considerable practical and theoretical interest in the behavior of aqueous aluminum in the oceans (where it is one of the highly reactive elements), in geochemical studies of aluminosilicates and related systems, and in water treatment technology (coagulation and... 

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