Clay-bound

Clay minerals behave like Bronsted acids, donating protons, or as Lewis acids (Sect. 6.3), accepting electron pairs. Catalytic reactions on clay surfaces involve surface Bronsted and Lewis acidity and the hydrolysis of organic molecules, which is affected by the type of clay and the clay-saturating cation involved in the reaction. Dissociation of water molecules coordinated to surface, clay-bound cations contributes to the formation active protons, which is expressed as a Bronsted acidity. This process is affected by the clay hydration status, the polarizing power of the surface bond, and structural cations on mineral colloids (Mortland 1970, 1986). On the other hand, ions such as A1 and Fe, which are exposed at the edge of mineral clay coUoids, induce the formation of Lewis acidity (McBride 1994). 

In addition to the above suite of well logs, the newest type of log was obtained via NMR (here called CMR) as shown in Figure 7.37. In this new method, the capillary, clay-bound, and free water (on the right) as determined by the NMR log, are subtracted from the total porosity as determined by the density tool (not shown) to obtain the hydrate saturation in the middle column. 

Figure 7.37 (See color insert following page 390.) 5L-38 CMR logs showing hydrate extent at depths between 900 and 930 m. Note that hydrates are obtained by the difference (middle column) between the total porosity as determined by density (not shown), and the capillary, clay-bound and free water determined by NMR.

Jones, K. D. Tiller, C. L. (1999). Effect of solution chemistry on the extent of binding of pherratrthretre by a soil humic acid a comparison of dissolved and clay bound humic. Environmental Science and Technology, 33, 580-7. 

Sorption thermodynamic functions of nitrous oxide, N2O, are described for zeolites NaLSX and CaLSX in shapes cA clay-bound beads. They were determined by the Sorption Isosteric Method (SIM) over complete ranges of sorption-phase concentration and compared with those for carbon dioxide, C(>2. nepo earlier for the same NaLSX sorbent... 

Figure 1. Sorption isosteres fbrN20 on NaLSX zeolite (clay-bound beads).

Besides clay-bound ware, there are also products composed of pure SiC, which, however, require very high firing temperatures and are utilized in special applications only. Silicon nitride or oxynitride can also serve as the binding phase the materials are highly refractory and can be produced at comparatively low temperatures by reactive sintering (cf. Chapter IV, Section 6.5). 

There have again been a number of reports relating to the use of O2 in non-traditional environments. Thus the O2 oxidation of electron-rich substrates such as quinol, 1-naphthol and anthracene with bentonite-bound methylene blue and hydrotalcite-bound rose Bengal has been described. These clay-bound sensitizers have been recovered and reused up to three times with only a small loss in efficiency, and, it is claimed, are more stable with respect to bleaching. The fullerene-coated beads already described (Scheme 7) have been used to promote the conversion of 1-naphthol to 1,4-naphthoquinone. The conventional methylene blue sensitized oxidation of 3-bromo-2,5-bis-(thio)furans affords thiomaleates (Scheme 16) which have synthetic potential as dienophiles and Michael acceptors. The 3-bromo-2-thiofuran (105), in a similar fashion, gives a 4-oxobutanethioate whereas the 2,3-bis-(thio)furan (106) gives a y-butyrolactone. 

Demaneche, S., Jocteur-Monrozier, L., Quiquampoix, H. and Simonet, P. (2001) Evaluation of biological and physical protection against nuclease degradation of clay bound plasmid DNA. Applied and Environmental Microbiology 67, 293-299. 

Studies of rock cores from oilfields are used in the petroleum industry to assess the hydrocarbon content of rock strata and the ease with which the oil can be recovered. The GeoSpecT NMR Rock Core Analyser, a 2 MHz TD-NMR from Oxford Instruments, can provide information on the fluids in oil- and water-saturated rock including oil viscosity and clay-bound water, porosity, fluid distribution, and permeability. Rock cores can be studied at high temperatures and pressures and the instrument can provide diffusion and imaging information. 

The composition of these materials has been investigated further by IR and NMR spectroscopy, and the absorption of a tannin as a representative polyphenolic compound to iron-containing and iron-free clays investigated. A sample of low grade oil sand, containing a considerable percentage of clay, was also examined for the presence of clay-bound organic materials. 

The structure of the counterion present in Super Filtrol initiated copolymerizations is unknown. However, the material consists of clay-bound sulfuric acid and presumably the counterion is sulfate bound to a silico-aluminate matrix. 

Holtzinger, G. Marie, G. Pigments based on clay-bound water-soluble dyes. Fr. Demande FR 2879097, 2006 Chem. Abstr. 2006,145, 69332. 

SAll reactions were carried out at 90° C under the following conditions 2.0 mmol of n- pentylbromide in 6.0 mL of toulene 20 mmol of KCN in 3.0 mL of water 0.073 mol of clay-bound onium ion. 

We have demonstrated similar effects using a zeolite or pillared clay bound to an electrode surface (3). Molecules partition, according to their size, into sites on the external or internal surface of the zeolite or clay, and the externally bound monolayer mediates electron transfer between the electrode and molecules within the particle. An interesting example of such spontaneous partitioning of molecules occurs when zeolite Y is ion-exchanged with small redox-active cations such as FcR" ", and with large metal tris(2,2 -bipyridyl) complexes. The 13 A diameter Os(bpy)32+ ion is substitution inert, and is therefore blocked from entry into the internal... 

In conclusion, the decomposition of aflatoxin proceeded relatively quickly in all soils except for the silty clay loam soil. Even the presence of extremely high concentrations of aflatoxin in soil failed to affect the rate of aflatoxin decomposition. The decomposition of aflatoxin in the silty clay loam soil proceeded at a reduced rate compared to the other three soils. The reduced rate of decomposition in this soil was probably due to the binding of aflatoxin to clay. Bound aflatoxin, or its decomposition products, degrade slowly, probably only upon desorption back into the soil solution. Hence, because aflatoxin is either adsorbed to soil exchange sites or degraded relatively quickly, the presence of aflatoxin would be expected to present few, if any, adverse environmental effects. 

Total void volume. Clay-bound water is included in pore volume... 

FIGURE 2.11 Volumetric description of a hydrocarbon-bearing clastic and carbonate reservoir. CBW, clay-bound water BVI, bulk volume irreducible/non-movable water BVM, bulk volume... 

NMR is not the end all to petrophysics. It is a new tool for understanding describing the subsurface both reservoir non-reservoir rocks which expands the petrophysical content of our logging data, providing direct estimates of irreducible water, clay bound water the permeability. 

Rook matrix Clay-bound water Capillary-bound water Movabie fiuids OBM filtrate Oil G a s... 

Clay-bound water creates the shortest relaxation time. This clay mineral-bound water effect is controlled by clay mineral properties. Therefore, relaxation time correlates with other interface properties of clay minerals such as specific internal surface and cation exchange capacity (CEC Table 3.3). Thus, T2 could be used as a CEC indicator (see, for example, Martin and Dacy, 2004). 

FIGURES./ NMR data processing—principle. Measured data are in a time domain. The inversion process results in a partitioning of the individual relaxation contributions (bulk volumes) with the three regions clay-bound water (CBW), capillary-bound or immovable water (BVl), and free movable water (BVW). Regions are separated by cut-offs. 

Archie s equations are based on the condition that the electrolytic conductivity of the pore water is the only conductivity component in the rock. This rock type is called clean rock . Natural rocks frequently have some additional conductive components. Most important are clay minerals with clay-bound water-forming shaly rocks or shaly sands. 

Prammer, M.G., Drack, D.E., Bouton, J.C., Gardner, J.S., 1996. Measurement of clay-bound water and total porosity by magnetic resonance logging. Log Anal. 37, 61-69. November-December. 

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