Sepiolite zeolitic

HCOs, Cr, F, and N03 The initial pore water chemistry is based on a sample that was ultracentrifuged from the proposed repository host rock (Tptpmn). Minerals considered include silica phases (a-cristobalite, quartz, tridymite, amorphous silica, and opal-CT), calcite, feldspars, smectites, illite, kaolinite, sepiolite, zeolites, fluorite, hematite, and gypsum. Treatment of CO includes gas-water equilibration, diffusion, and advection. 

There are several other types of minerals commonly found in clay particle size mineral assemblages (i.e.,< 2 microns diameter, Krumbein and Pettijhon, 1938). Aside from quartz and amorphous materials, the two most important mineral groups are sepiolite-palygorskite and zeolites. These two groups are similar in that they both contain free 1 0 molecules in their structure. However the Si-0 linkage is quite different in each case. 

Sepiolite and palygorskite are frequently associated In natural deposits. They are both fibrous in form, a characteristic dictated by their chain-type (linear) structure. They contain hydroxyls, zeolitic... 

Borja and Banks also performed a kinetic study of the anaerobic digestion of soft drink wastewater using bioreactors containing various suspended supports. Again, bentonite, zeolite, sepiolite, saponite, and polyurethane foam were used as substrata onto which the microorganisms affecting purification were immobilized. Similar results were noted. Vieira et al. also studied the kinetics of anaerobic sludge immobilization in the matrix of a polyurethane foam.- ... 

Fibrous zeolites (natrolite, scolecite, thomsonite, edingtonite) Fibrous clay minerals (attapulgite sepiolite)... 

H, 2H and 29Si solid state NMR study of guest acetone molecules occupying the zeolitic channels of partially dehydrated sepiolite clay... 

Sepiolite clay (<100 mesh) was heated in air at 120°C in order to remove the zeolitic and surface bound water molecules. The partially dehydrated clay mineral was subsequently exposed to acetone vapor at room temperature for a period of four days. H and 29Si CP MAS-NMR experiments revealed that the acetone molecules penetrated into the microporous channels of the sepiolite structure. Broad line 2H NMR studies using acetone-d6 revealed that, in addition to fast methyl group rotations, the guest acetone-d6 molecules were also undergoing 2-fold re-orientations about the carbonyl bond. The presence of acetone-d6 molecules adsorbed on the exterior surfaces of the sepiolite crystals was also detected at room temperature. 

Finally, the 29Si CP/MAS-NMR spectrum of a partially dehydrated sepiolite that was subsequently exposed to acetone vapor is presented in Fig. 2c, and is strikingly similar to the spectrum of the original, untreated sepiolite (Fig. 2a). Since zeolitic water molecules are not present in this sample, and in light of the discussion of the partially dehydrated sepiolite sample, it appears that the acetone molecules have penetrated inside the microporous channels and reversed the structural changes that were caused by partial dehydration. Thus Fig. 2c confirms that acetone molecules enter the microporous channels of sepiolite, and are not simply adsorbed on the crystallite exterior surfaces. 

H, 2H and 29Si Solid State NMR Study of Guest Acetone Molecules Occupying the 551 Zeolitic Channels of Partially Dehydrated Sepiolite Clay M.R. Weir, G.A. Facey and C. Detellier... 

The catalysts studied were prepared by dispersing 20 wt% of a USY zeolite with a 2.433 nm of unit cell size in either silica (Basf (D-ll-11)) or aluminic sepiolite (SA1). The final catalyst was steamed at 750flC in a 100% steam for 6 hours. 

At this point we have an aluminum type sepiolite which shows mild acidity and could be used as a component for FCC catalysts. Then, we have checked if the aluminium containing sepiolite can also passivate vanadium. To do that, two FCC catalysts containing 20% of a REHY zeolite in either 80% of a 23 wt% A1203 containing silica-alumina, or 80% of aluminic sepiolite were prepared. Both samples where impregnated to incipient wetness with a V naphthenate/xylene mixture (15), in order to introduce 6000 ppm of vanadium. Both samples were steam deactivated... 

The selection of the more suitable nature for a porous support was based in the criteria of thermal and thermo dynamical stability (AG 0, chemically inert support) in the sulfurization step. The melting temperatures of 1000 C or higher, are required because zinc ferrite phase is prepared about 950 C. One representative material from each of the aforementioned categories has been selected for the preparation of every supported sorbent Coimnereial sepiolite (Tolsa, S.A., Spain), USY zeolite (Zeolyst Ine., U.K.), and Zr02, m.p. 2500°C,... 

These results show that zinc ferrite has been formed, but in sepiolite and USY zeolite the enstatite and hercynite networks substitute some of their ions for Fe and Zn, therefore masking the ffanklinite network. In the Zr02 case such substitution does not occur, appearing the pure oxide together with the fi-anklinite (6-8%), as theoretically expected. 

The present-day sediments of the Atlantic do not contain a substantial amount of zeolite (Elderfield, 1976). Clinoptilolite has been found, however, in association with sepiolite, quartz, and mont-morillonite (Hathaway and Sachs, 1965 Bonatti and Joensuu, 1968). The clay minerals palygorskite and sepiolite are usually minor constituents of marine sediments (Hathaway, 1979), and may be detrital (Weaver and Beck, 1977) or authigenic. Their hydrogenous occurrences are usually in basal sediment sections exposed to fluids of elevated temperarnres (Bonatti and Joensuu, 1968 Church and Velde, 1979 see below). 

Many other materials, including synthetic aluminas, aluminum carbonates, aluminum silicates, magnesium silicates, various forms of attapulgite and sepiolite (81-83), alumina-pillared acid-activated montmorillonite (84), synthetic mica mont-morillonite, HY-zeolite, zirconium phosphate (85), mica, kaolin, and synthetic hectorite (86), have been evaluated for their ability to purify virgin fats and oils, but none were as good as acid-activated bentonite. 

To set up a more environmentally friendly process, it is mandatory to replace the caustic soda by solid bases. Many catalysts such as zeolites [2], alumina [3,4], sepiolite [5] and hydrotalcites [6,7] have been regarded as promising solid basic materials. Hydrotalcites, which are anionic clays, are the subject of this investigation. They are layered double hydroxides with the general formula [M(II)i.xM(III)x(0H)2].[A" x/n].mH20. The host layers are charged positively by replacement of divalent metal cations usually Mg ", Ni and... 

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