Surface organophilicity

Stabilization of silica-thickened grease with basic aluminum stearate probably - involves adsorption of the aluminum on the silica with the fatty add anions attached (503). Silica fillers for elastomers are improved by rendering the surface organophilic with basic chromium complexes of the type... 

Recently, Mark and co-workers also reported on organophilic silica formed by the combination of the sol-gel procedure and water-in-oil micro-emulsion method, in which methacryloyloxypropyltrimethoxysilane was used as one component of silica matrix [8]. The size of the silica particle was controlled by the content of water and emulsifier used. The surface of the particles was effectively covered with methacryloyl. organic groups. This organophilic silica is expected to be used as a novel component of composite materials. 

Bentonite is an impure clay that is formed by weathering of volcanic tuffs. It contains a high content of montmorillonite. Bentonites exhibit properties such as ability to swell, ion exchange, and thixotropy. Properties can be modified by ion exchange, for example, exchange of earth alkali metals to alkali metals. The specific surface can be modified with acid treatment. Organophilic properties can be increased by treatment with quaternary ammonia compounds. 

Layered phosphate/phosphonate and phosphonate materials, obtained by substitution of the phosphate moiety by phosphonate groups, display interesting tunable hydrophilic/organophilic properties for adsorption processes. When Candida rugosa lipase (CRL) is simply equilibrated with zirconium phosphate and phosphonate [135,136], immobilization was demonstrated to take place at the surface of the microcrystals. However, because lipase exhibits a strong hydrophobic character, its uptake by zirconium phosphate and phosphonate was much more related to the hydrophobic/hydrophilic character of the supports than to the surface area properties. A higher uptake is observed for zirconium-phenylphosphonate (78 %)... 

The ZnO surface is made more organophilic by coating it with oil and propionic acid. The ZnO is often deaerated and sometimes pelletized or granulated to improve handling properties. 

A hydrated metal ion (Mz+) will always prefer the aqueous phase to the organic phase. To get the metal ion to extract, some or all of the inner hydration sphere must be removed. The resulting complex must be electrically neutral and organophilic, that is, have an organic surface that interacts with the organic solvent. This can be done by ... 

Mass-transport limitations are common to all processes involving mass transfer at interfaces, and membranes are not an exception. This problem can be extremely important both for situations where the transport of solvent through the membrane is faster and preferential when compared with the transport of solute(s) - which happens with membrane filtration processes such as microfiltration and ultrafiltration - as well as with processes where the flux of solute(s) is preferential, as happens in organophilic pervaporation. In the first case, the concentration of solute builds up near the membrane interface, while in the second case a depletion of solute occurs. In both situations the performance of the system is affected negatively (1) solute accumulation leads, ultimately, to a loss of selectivity for solute rejection, promotes conditions for membrane fouling and local increase of osmotic pressure difference, which impacts on solvent flux (2) solute depletion at the membrane surface diminishes the driving force for solute transport, which impacts on solute flux and, ultimately, on the overall process selectivity towards the transport of that specific solute. 

Activated carbon is by far the most widely used adsorbent. It is available in a wide range of different forms that differ mainly in pore size and pore size distribution. The carbon surface is essentially nonpolar although some polarity can be imparted by surface oxidation or other pre-treatments. It is widely used for removal of low concentrations of organics, either from aqueous streams (for example, decolorization of sugar or water treatment) or from vapor streams (for example, in range hoods and other pollution-control devices). Crystalline silica adsorbents such as silicalite are also organophilic but are substantially more expensive than activated carbon so their application is generally limited to situations where, for some reason, the use of carbon is not appropriate. 

The specific activity of Ti-sites in oxidation with aqueous H202 was shown to decrease from microporous to mesoporous molecular sieves such as MCM-41 and HMS. The surface hydrophilicity of the latter mesoporous silicates is likely one of the main reasons for the low activity of Ti sites.[47] Water molecules adsorbed on the surface silanol groups would limit the access of organophilic reagents to the Ti sites.1751 This can be limited, to a certain extent, by grafting hydrophobic groups on the surface silanols.1761... 

Catalytic studies have extended the applications of TS-1 from early aromatic hydroxylation to the oxidation of olefins, alkanes, alcohols, amines and thioethers, and to other minor reactions. A combination of three factors is the basis of its effectiveness the high activity of Ti peroxy species, the organophilic properties of the surface and the size of the pores in the range of molecular dimensions. For... 

Frieser292 has shown that hydrophobic, hydrophilic, and organophilic Si02 surfaces may be distinguished easily by two independent contact-angle measurements with different liquids. Interest in Si02 surface chemistry has centered, however, on the characterization (principally by means of i.r. and e.s.r. spectroscopy) of the functional groups present on surfaces subjected to... 

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