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Clay, elimination with

Thus, under conditions of higher salinity (-28%) in a hydrodynamically stable environment the composition of the clay mineral spectrum may vary considerably. There is a synthesis (or transformation) of clay minerals with a stable lattice when halite is being deposited. This is evidently tied to the physico-chemical conditions leading to the start of crystallization of halite (rock salt). A basin saturated in NaCl is characterized by a low degree of hydratization. The lithification of halite during which any excess water is being eliminated takes place rapidly and favours the dehydration of the interfoliar space of clay minerals which prove to be most apt for transformations. [Pg.37]

Electroultrafiltration (EUF) combines forced-flow electrophoresis (see Electroseparations,electrophoresis) with ultrafiltration to control or eliminate the gel-polarization layer (45—47). Suspended colloidal particles have electrophoretic mobilities measured by a zeta potential (see Colloids Elotation). Most naturally occurring suspensoids (eg, clay, PVC latex, and biological systems), emulsions, and protein solutes are negatively charged. Placing an electric field across an ultrafiltration membrane faciUtates transport of retained species away from the membrane surface. Thus, the retention of partially rejected solutes can be dramatically improved (see Electrodialysis). [Pg.299]

Of even more economic importance is the rheological impact of the addition of KC1 to conventional water-base drilling fluids. KC1 causes undesirable increases in both yield point and gel strength that can only be eliminated by chemical disperants or by dilution with fresh water. Dilution in turn requires more KC1 for clay inhibition, and the cycle continues with mud costs escalating exponentially. [Pg.627]

The intercalant solution was prepared by titration of an Al3+/ Fe3+cationic solution with 0.2 molL"1 NaOH. The cationic solution contained 0.18 and 0.02 molL"1 of A1C13 and FeCl3, respectively. The NaOH solution was slowly added to the cationic solution at 70°C until the OH/cation molar ratio was equal to 1.9. The intercalant solution was added to the clay suspension under stirring. The final ( Al+Fe) /clay ratio was equal to 3.8 mmol/g of dry clay. After aging for 24h, the pillared clay precursor was washed until total elimination of chloride ions, dried at 60°C and finally calcined at 500°C for 5h. The resulting material is (Al-Fe)PILC. [Pg.310]

The main components of FCC catalysts are Zeolite Y, e.g., REY orUSY as the major active component (10 to 50%), and a binder that is typically an amorphous alumina, silica-alumina, or clay material. In addition to these main components, other zeolite components, e.g., ZSM-5, and other oxide or salt components are quite frequently used additives in the various FCC catalysts available on the market. The addition of 1 to 5% ZSM-5 increases the octane number of the gasoline. ZSM-5 eliminates feed compounds with low octane numbers because it preferentially center-cracks n-paraffins producing butene and propene [14], These short-chain olefins are then used as alkylation feedstocks... [Pg.112]

Mr. Don Clay, Director of the Office of Toxic Substances, discussed the premanufacture review procedures and experience with PMNs to date at a meeting of the Organization for Economic Cooperation on Development (OECD) Chemicals Forum in December, (10). He noted that EPA s chemistry, toxicology, and exposure assessment teams normally complete their preliminary evaluation within a week of receipt of a PMN, and, that preliminary assessment eliminates about 50 percent of the substances as chemicals of low concern. They then proceed to structure activity analysis and reasonable worst case assumptions to assess unreasonable risk or the need for more data. [Pg.32]

A method [62] has been described for the determination of down to 2.5pg kg-1 alkylmercury compounds and inorganic mercury in river sediments. This method uses steam distillation to separate methylmercury in the distillate and inorganic mercury in the residue. The methylmercury is then determined by flameless atomic absorption spectrophotometry and the inorganic mercury by the same technique after wet digestion with nitric acid and potassium permanganate [63]. The well known adsorptive properties of clays for alkylmercury compounds does not cause a problem in the above method. The presence of humic acid in the sediment did not depress the recovery of alkylmercury compounds by more than 20%. In the presence of metallic sulphides in the sediment sample the recovery of alkylmercury compounds decreased when more than lmg of sulphur was present in the distillate. The addition of 4M hydrochloric acid, instead of 2M hydrochloric acid before distillation completely, eliminated this effect giving a recovery of 90-100%. [Pg.409]

For instance, 2-methylpropene reacted with acetic acid at 18°C in the presence of Al-bentonite to form the ester product (75). Ion-exchanged bentonites are also efficient catalysts for formation of ketals from aldehydes or ketones. Cyclohexanone reacted with methanol in the presence of Al-bentonite at room temperature to give 33% yield of dimethyl ketal after 30 min of reaction time. On addition of the same clay to the mixture of cyclohexanone and trimethyl orthoformate at room-temperature, the exothermic reaction caused the liquid to boil and resulted in an almost quantitative yield of the dimethyl ketal in 5 min. When Na- instead of Al-bentonite is used, the same reaction did not take place (75). Solomon and Hawthorne (37) suggest that elimination reactions may have been involved in the geochemical transformation of lipid and other organic sediments into petroleum deposits. [Pg.479]

Also other Type B and C series from Table II are consistent with the above elimination mechanisms. The dehydration rate of the alcohols ROH on an acid clay (series 16) increased with the calculated inductive effect of the group R. For the dehydrochlorination of polychloroethanes on basic catalysts (series 20), the rate could be correlated with a quantum-chemical reactivity index, namely the delocalizability of the hydrogen atoms by a nucleophilic attack similar indices for a radical or electrophilic attack on the chlorine atoms did not fit the data. The rates of alkylbenzene cracking on silica-alumina catalysts have been correlated with the enthalpies of formation of the corresponding alkylcarbonium ions (series 24). Similar correlations have been obtained for the dehydrosulfidation of alkanethiols and dialkyl sulfides on silica-alumina (series 36 and 37) in these cases, correlation by the Taft equation is also possible. The rate of cracking of 1,1-diarylethanes increased with the increasing basicity of the reactants (series 33). [Pg.169]

The dye-clay composites were prepared by dispersing the clays in each solvent containing the dye at a quantity of 10-200% of the CEC. This experimental procedure led to almost complete intercalation at room temperature for 2-7 days. The composite was recovered by filtration and washing several times with each solvent for eliminating an excess of dye, and then dried in air. Assuming that the loss of dye adsorbed on the surface was fairly small upon washing, the net weight of dye intercalated was estimated from the residual dye concentration in a solvent measured by a colorimetric analysis. [Pg.190]

Isatoic anhydride undergoes a one-step conversion to o-aminophenyloxazolines 2 with amino alcohols via elimination of carbon dioxide. The reaction is carried out in the presence of kaolinitic clay in refluxing chlorobenzene. These o-aminophenyloxazolines, in particular, those derived from chiral amino alcohols,... [Pg.336]

Frequently substantially more than catalytic amounts of a Lewis acid metal halide are required to effect Friedel-Crafts alkylation. This is due partly to complex formation between the metal halide and the reagents or products, especially if they contain oxygen or other donor atoms. Another reason is the formation of red oils. Red oils consist of protonated (alkylated) aromatics (i.e., arenium ions) containing metal halides in the counterions or complexed with olefin oligomers. This considerable drawback, however, can be eliminated when using solid acids such as clays,97 98 zeolites (H-ZSM-5),99,100 acidic cation-exchange resins, and perfluoro-alkanesulfonic acid resins (Nafion-H).101-104... [Pg.232]

The relatively strong interaction of cationic contaminants with negatively charged soil constituents, for example, is expected to decrease bioavailability. This has been shown to be the case for diquat, in which intercalation into internal clay surfaces eliminates microbial degradation of the compound (Weber and Coble, 1968). Decreased bioavailabilities forbenzylamine in association with montmorillonite (Miller Alexander, 1991), quinoline bound to hectorite or montmorillonite (Smith etal., 1992), and cationic surfactants with humic materials or montmorillonite (Knaebel et al., 1994) have also been reported. [Pg.46]


See other pages where Clay, elimination with is mentioned: [Pg.70]    [Pg.1182]    [Pg.64]    [Pg.37]    [Pg.19]    [Pg.125]    [Pg.378]    [Pg.349]    [Pg.150]    [Pg.229]    [Pg.251]    [Pg.253]    [Pg.291]    [Pg.49]    [Pg.626]    [Pg.141]    [Pg.249]    [Pg.309]    [Pg.236]    [Pg.845]    [Pg.483]    [Pg.439]    [Pg.127]    [Pg.624]    [Pg.30]    [Pg.409]    [Pg.365]    [Pg.816]    [Pg.65]    [Pg.553]    [Pg.100]    [Pg.378]    [Pg.336]    [Pg.352]    [Pg.353]    [Pg.215]    [Pg.55]   
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Elimination with

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