Saponite composition

As a function of the dye content intercalated, the relative intensity of fluorescence, the maximum wavelength in the fluorescence spectrum of lax d-spacing are illustrated in Fig. 2(a) for the pyronine Y-saponite composite (referred to as PY-SA), and Fig. 2(b) for the rhodamine 590-saponite composite (referred to as R590-SA). 

This makes the magnitude and direction of the eiementai fluxes difflcuit to generai-ize because of their dependence on such variabies as the water s temperature and circuiation rate and the rock s porosity and chemicai composition. Low-temperature weathering of basait is aiso accompanied by precipitation of iron oxides and iron uptake into various ciays (nontronite, saponite, and ceiadonite). 

Fibrous saponite, with the analyzed chemical formula (Mgs g, AIq i, F o.i)(Si6.76> All o4 Fe 0.2) 02o(OH)4 IOH2O, also had Cao.i and Mgo4 as exchangeable ions (Midgely and Grass, 1956). Saponite is an example of a trioctahedral smectite. The variable chemical compositions of the smectites adds to the difficulties of accurate identification of these minerals. 

In order to prevent the effect of Fe impurities on fluorescence [6], an artificial clay, saponite (referred to as SA), was used as the starting material. Saponite with high transparency in the visible region was obtained from KUNIMINE Industry Co. Its chemical composition determined by atomic absorption spectroscopy was represented as... 

On addition of Na -saponite to the rhodamine-ethanol solution and the pyronine-ethanol solution, the color of the solutions gradually faded within a few hours, even at room temperature. All the composites were intensely colored, namely bright red for Rhodamine 590 and cardinal for Pyronine Y. 

Fig. 3. X-ray powder diffraction patterns for saponite-coumarine composites with coumarine at 65, 75, 85, 95 and 105 mmoI/IOO g-clay.

After the experiments, significant quantities of newly formed minerals were observed at the cold extremity of the tube, pointing to a fast material transport by diffusion from the hot to the cold end of the tube. The following spatial distribution of newly formed phases, reflecting the temperature profile, was observed in both runs (Fig. 8) quartz + K-feldspar + plagioclase + Mg-rich saponites (hot extremity) quartz + K-feldspar + plagioclase (middle of the tube) and alkaline or Ca-rich clays + quartz + plagioclase (cold extremity). The cation composition of the phyllosilicates was similar in both experiments. Some newly fonned quartz crystals... 

Because the compositions are basic, the expanding minerals are trioctahedral and they are apparently associated in all facies with chlorite. The occurrence of a regularly interstratified montmorillonite (saponite) -chlorite mineral, corrensite, is typified by an association with calcic zeolites and albite. Temperature measurement in the "hydrothermal" sequences at several hundred meters depth indicate that the ordered, mixed layered mineral succeeds a fully expandable phase between 150-200 C and this ordered phase remains present to about 280°C. In this interval calcium zeolites disappear, being apparently replaced by prehnite. The higher temperature assemblage above corrensite stability typically contains chlorite and epidote. 

The material from the Hector area of California is believed to have formed by the action of hot spring waters containing Li and F on clinoptiolite. The Mg was obtained from the alkaline lake waters (Ames and Goldich, 1958). The material from Morocco is associated with marls and is believed to be authigenic. These two types of trioctahedral smectite appear to be the only ones with a relatively pure Si tetrahedral sheet. No analyses were found which indicated tetrahedral Al values between 0.02 and 0.30. Analyses of saponite indicate there is complete isomorphous substitution between the range Si3.70 Al0.3o and Si3.0s Al0.92 (Table XXXIX). Caillere and Henin (1951) reported an analysis of a fibrous expanded clay (diabantite) which had a tetrahedral composition of Si3.i7 Alo.49 Fe3+0.34. There is some question as to whether this should be classified as a smectite regardless, it indicates the possibility of Fe3+ substitution in the tetrahedral sheets of the trioctahedral 2 1 clays. 

The strain in saponites produces a lath morphology. These laths vary considerably in width however, the data are insufficient to relate lath width to composition. There... 

Fig.25. Ternary plot based on the composition of the octahedral sheet of the dioctahedral 2 1 clay minerals, attapulgite and trioctahcdral saponite. Fe2 + was excluded.

Effect on clay dispersion, 414 Hazard, 423-426 Saponite, 123-124 Structure, 124 Composition, 124... 

Theoretically this sequence should be observed in the deposition of purely carbonate sediments. In the actual conditions of nature, including deposition of the BIF, a substantial part of the Fe and Mg went into the composition of primary silicates of greenalite, minnesotaite, and iron chlorite type. Taking ferrous greenalite—FejSi205(0H)4)—and magnesian saponite — Mg3Si40,o(OH)2 — as the stable end members, one can find the interrelationships between carbonates and silicates. 

CR2 chondrite matrices are predominantly composed of olivine with grain sizes of 0.2-0.3 p.m accompanied by intergrowths of serpentine and saponite with dimensions of 20-300 nm and minor sulfide and magnetite grains 0.1-25 p.m in size (Zolensky et al., 1993 Endress et al., 1994). CR2 chondrites also contain 3 vol.% of more altered matrix lumps mostly 0.1-1 mm in size, which are similar in bulk composition to the other matrix material (Endress et al., 1994). However, phyllosilicates, magnetite and chondrule fragments are more abundant in the matrix lumps than in interstitial material, and sulfides are richer in nickel suggesting that the lumps are chondritic clasts that formed in a totally different environment. 

Table I Approximate composition of saponite based on chemical analysis.

Figure 15.11. Tensile modulus of composites made from nylon and different fillers (montmorillonite, saponite, hectorite and mica) vs. N-NMR chemical shifts of model compounds of fillers. [Adapted, by permission, from Usuki A, Koiwai A, Kojima Y, Kawasumi M, Okada A, Kurauchi T, Kamigaito O, J. Appl. Polym. Sci., SS, No.l, 1995, 119-23.]...

The necessity to develop hydrotreating catalysts with enhanced activity stimulates the search for alternative catalyst supports. It was shown that clay-supported transition metal sulfides can efficiently catalyze hydrodesulfurization (HDS) of thiophene [1-3]. However, the large scale application of the catalysts based on natural clays is still hampered, mainly due to the difficulties in controlling the chemical composition and textural properties. Synthetic clays do not suffer from these drawbacks. Recently, a novel non-hydrothermal approach was proposed for the synthesis of some trioctahedral smectites, namely saponite... 

Other than montmorillonite, synthetic mica, saponite and hectorite were used to synthesize a nylon 6-clay hybrid. The nano composites fabricated by using each of these types of clay were called NCH, NCHM, NCHP and NCHH. 

Silicate layers were uniformly dispersed in nylon 6 in NCH, NCHM, NCHP and NCHH at the molecular level. The thicknesses of the silicate layers were 1 nm in all of these nanocomposites, but their widths varied depending on the type of clay used. An examination of each photograph revealed that the width of the nano composites fabricated using montmorillonite and synthetic mica were about 100 nm and those of the nanocomposites fabricated using saponite and hectorite were about 50 nm. 

Sample of natural Na-montmorillonite (KUNIPIA F) and of i thetic saponite (SUMECTON SA) were obtained from Kunimine Industries Co., Ltd. of Japan. The chemical composition data is shown in Table 5-1. 

Saponites can easily be prepared at 90°C and 1 atmosphere within some hours. Adjustment of the chemical composition of the octahedral layer (Mg, Zn, Ni, Co, or a combination of Mg and Zn) and the tetrahedral layer (desired Si/Al-ratio) of the synthetic saponites is viable. The composition of the octahedral layer has a large effect on the texture of the synthetic saponites. 

The two end members of this group with mainly tetrahedral substitutions are beidellite and saponite, which are di- and trioctahedral smectites, respectively. The corresponding end members with mainly octahedral substitutions are mont-morillonite and hectorite. Another common smectite, nontronite, is an iron-rich mineral. Chemical compositions of various smectite samples are provided in Table 2. Montmorillonite is the most common mineral of this group it is named for its location in Montmorillon, France. Figures 3d and 3e provide SEM views of the textural morphology of two montmorillonites. A common industrial mineral is bentonite, which is actually a montmorillonite of volcanic ash origin that contains a significant amount of impurities, such as cristobalite (a-quartz), that is intimately mixed with the clay. 

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