Chabazite composition

Figure 33b. Calcic zeolites as a function of their compositions in Al-Si-Cax coordinates assuming Calcium end members. F = feldspar G = gismon-dine La = lawsonite Sc = scolectite Ph = phillipsite Ch = chabazite ...

Figure 2. Cation elution curves (left scale) and lead breakthrough curve (right scale) on chabazite tuff bed in its original cationic composition Feed composition 110 mg-1 Pb feed flow rate 6 ml-min...

Prepolymerization of Silicate. From phosphate-buffered mixtures of identical chemical composition, different zeolites crystallize depending on the degree of prepolymerization of the silicate. Polymeric silicates tend to give ZK-15 or zeolites of chabazite structure [low-silica ZK-14 (17)] in the same pH range where metasilicate causes zeolite Y to crystallize (Table IV). Thus, either the depolymerization of waterglass is slower than generally thought or the precursors formed with partially depolymerized silicate are stabilized sufficiently to prevent further rapid depolymerization. 

Figure 2. Plot showing the compositional variation of chabazite...

The RIR analysis, performed on the zeolite tuffs and on the enriched samples in order to estimate the effectiveness of the enrichment processes, showed that in the mineralogical composition of the phillipsite- and chabazite-enriched materials minor contents of other cation exchanging phases were present. These, however, given their exiguity, were considered negligible (Table 1). 

Mineralogical composition of phillipsite- and chabazite-enriched materials... 

Table 2 reports the chemical composition and the formula of pure phillipsite and chabazite, obtained by microprobe analysis. Phillipsite appears to be rich in K, followed by Na and Ca, with minor amounts of Mg, chabazite is rich K and Ca with minor contents of Na and Mg, which is typical for the Italian sedimentary zeolites [6,7]. 

Baglio V, Di Blasi A, Aric6 AS, Antonucci V, Antonucci PL, Nannetti F, Tricoli V (2005) Investigation of the electrochemical behaviour in DMFCs of chabazite and clinoptilolite-based composite membranes. Electrochim Acta 50 5181-5188... 

Figure 7.5. Compositional synthesis windows for the Na20-Al203-Si02-H20 system at 100°C and 90-98 mol% H2O. Source of Si02 is (a) sodium silicate and (b) colloidal silica. The area enclosing a letter represents the composition that yields the corresponding phase, while the + marks the typical composition of the product. A, X, and Y = zeolites types A, X, and Y B = zeolite P R = chabazite S = gmelinite and HS = hydroxysodalite (from Breck and Flanigen, 1968, with permission).

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