Natural glasses, zeolitization

AIELLO (R.), COLELLA (C.) and SERSALE (R.), 1970. Zeolite formation from synthetic and natural glasses. Arne. Chem. Soc. 2nd Int. Zeolite Conf., 48-58. 

Two synthesis variables seemed to have received most attention in the work reviewed here, the cation composition and the nature and source of the aluminosilicate reactant. Extensive use of mixed bases of the alkali, alkaline earth, and organic cations have been reported as well as a wide variety of reactant aluminosilicates including solutions, hydrogels, glasses, kaolin (raw and calcined), and naturally occurring zeolites. 

Zeolite Formation from Synthetic and Natural Glasses... 

Zeolitization of Natural Glasses. The research on the zeolitization of natural glasses has been devoted essentially to the investigation of the most favorable conditions for the crystallization of the various zeolites obtainable. 

Solid surfaces nature of the surface of colloidal silica, clays, zeolites, silica gels, porous Vycor glasses, alumina rigidity, polarity and modification of surfaces... 

It follows that the thermodynamic potentials of the hydrogen and sodium ions in the glass must be affected by the concentrations in the solution or ionic replacement in the glass occurs. This power of ionic interchange is shared in common with glass by the naturally occurring hydrated silicates the zeolites. 

Glass-ceramics based on natural or synthetic basalts, various zeolites, and apatite/britholite were also developed (Saidl Ralkova 1966 Hayward 1988 Wronkiewicz et al. 1996 Sinkler... 

Honnorez, J. 1978. Generation of phillipsites by pala-gonitization of basaltic glass in seawater and the origin of K-rich deep-sea sediments. In Sand, S. B. Mumpton, F. A. (eds) Natural Zeolites,... 

If we consider the process of recrystallization of the acidic volcanic glass at surface conditions in the soil or sedimentary environment, the assemblage feldspar (plus alkali zeolites in many instances) -montmorillonite free silica can be deduced from the diagram- on the basis of bulk composition. This assemblage is common in such natural materials. 

In Figure 6.12 [2,25], the plot of the linear form of the osmotic isotherm equation, with B = 0.5, using adsorption data of NH3 adsorbed at 300 K in an homoionic magnesium natural zeolite sample labeled CMT (see Table 4.1), is shown. The adsorption data reported in Figure 6.12 were determined volumetrically in a Pyrex glass vacuum system, previously described in the case of the Dubinin equation [25,31], With this plot, it is possible to calculate the maximum adsorption capacity of this zeolite, which is m = Na = 5.07mmol/g and b = UK = -0.92 (Torr)05. 

In nature, there are large deposits of silica-rich volcanic ashes in coarse amorphous colloidal particles, some of which are fairly pure and quite readily soluble to alkali solutions. They are used often as an industrial source of silica. Impure volcanic ash which contains alumina is used as a detergent, filter aid and mild ion-exchange agent after alkali or acid treatment and as a raw material for the synthesis of zeolite and porous glass. 

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