Adsorptivity and hydrophobicity

Argillaceous formations are very reactive in the presence of water. Such formations can be stabilized by bringing them in contact with a polymer solution with hydrophilic and hydrophobic links [101-104]. The hydrophilic portion consists of polyoxyethylene, with hydrophobic end groups based on isocyanates. The polymer is capable of inhibiting the swelling or dispersion of the argillaceous rock resulting from its adsorptive and hydrophobic capacities. 

Comparing curves of Rp — tr (Fig. 2.44) [118], we conclude that, when there are no adhesive contacts of the inhibited film material and the electrode is absent, Rp and the kinetics of its variations will be defined by the penetrability and deformation of the film material along with the adsorption and hydrophobic properties of the Cl. 

The effect of water vapour on the activity of MCM-48 supported chromium catalysts for the destruction of TCE was reported by Kawi and Te. The results showed that a high concentration of water vapour (8,000 ppm) in the gas stream was detrimental to the catalytic activity of Cr/MCM-48 catalysts, whereas a lower concentration of water vapour (1,000 ppm) had negligible influence. These authors also showed that, although Cr/Si-MCM-48 showed quite similar stable activity at low concentration of water vapour in the gas stream, it had significantly higher TCE adsorption and hydrophobicity compared to Cr/MCM-48. 

Yang C, Kaipa U, Mather QZ, Wang X, Nesterov V. Venero AF, Omary MA (2011) Fluorous metal organic fiameworks with superior adsorption and hydrophobic properties towmd oil spiU cleanup and hydrocarbon storage. J Am Chem Soc 133 18094-18097... 

Surface-active substances alter the properties of soil minerals (e.g., layer silicates) by adsorption and hydrophobization of the surface. Even slight quantities of surfactants cause significant effects with respect to the transport and biological availability of pollutants in soils and sediments [16]. This may result in the accumulation of pollutants in the trophic stages of the food chain and the elimination of essential trace elements. Cationic surfactants, for example, cause a drastic alteration in the electrolyte equilibrium between the soil and soil solution due to ion exchange. Both essential cations (Ca, Mg, Na ) as well as toxic heavy metal ions (e.g., Cd ) are quantitatively displaced [11]. 

Furthermore, highly fluorous MOFs (FMOFs) with superior adsorption and hydrophobic properties... 

Hydrophilic and Hydrophobic Surfaces. Water is a small, highly polar molecular and it is therefore strongly adsorbed on a polar surface as a result of the large contribution from the electrostatic forces. Polar adsorbents such as most zeoHtes, siUca gel, or activated alumina therefore adsorb water more strongly than they adsorb organic species, and, as a result, such adsorbents are commonly called hydrophilic. In contrast, on a nonpolar surface where there is no electrostatic interaction water is held only very weakly and is easily displaced by organics. Such adsorbents, which are the only practical choice for adsorption of organics from aqueous solutions, are termed hydrophobic. 

A surprisiagly large number of important iadustrial-scale separations can be accompHshed with the relatively small number of zeoHtes that are commercially available. The discovery, characterization, and commercial availabiHty of new zeoHtes and molecular sieves are likely to multiply the number of potential solutions to separation problems. A wider variety of pore diameters, pore geometries, and hydrophobicity ia new zeoHtes and molecular sieves as weU as more precise control of composition and crystallinity ia existing zeoHtes will help to broaden the appHcations for adsorptive separations and likely lead to improvements ia separations that are currently ia commercial practice. 

The chemical adsorption of a relatively high molecular weight neutral polymer (poly(succinimide), M = 13000) on aminopropyl-Vydac 101 TP silica gel was applied by Alpert [47, 48] to prepare a reactive composite support for use in cation-exchange [47] and hydrophobic-interaction [48] chromatography of pro-... 

Some authors have suggested the use of fluorene polymers for this kind of chromatography. Fluorinated polymers have attracted attention due to their unique adsorption properties. Polytetrafluoroethylene (PTFE) is antiadhesive, thus adsorption of hydrophobic as well as hydrophilic molecules is low. Such adsorbents possess extremely low adsorption activity and nonspecific sorption towards many compounds [109 111]. Fluorene polymers as sorbents were first suggested by Hjerten [112] in 1978 and were tested by desalting and concentration of tRN A [113]. Recently Williams et al. [114] presented a new fluorocarbon sorbent (Poly F Column, Du Pont, USA) for reversed-phase HPLC of peptides and proteins. The sorbent has 20 pm in diameter particles (pore size 30 nm, specific surface area 5 m2/g) and withstands pressure of eluent up to 135 bar. There is no limitation of pH range, however, low specific area and capacity (1.1 mg tRNA/g) and relatively low limits of working pressure do not allow the use of this sorbent for preparative chromatography. 

One of the most attractive roles of liquid liquid interfaces that we found in solvent extraction kinetics of metal ions is a catalytic effect. Shaking or stirring of the solvent extraction system generates a wide interfacial area or a large specific interfacial area defined as the interfacial area divided by a bulk phase volume. Metal extractants have a molecular structure which has both hydrophilic and hydrophobic groups. Therefore, they have a property of interfacial adsorptivity much like surfactant molecules. Adsorption of extractant at the liquid liquid interface can dramatically facilitate the interfacial com-plexation which has been exploited from our research. 

Hu, B., Chen, C., Frueh, S.J., Jin, L., Joesten, R. and Suib, S.L. (2010) Removal of aqueous phenol by adsorption and oxidation with doped hydrophobic cryptomelane-type manganese oxide (K-OMS-2) nanofibers. Journal of Physical Chemistry C, 114, 9835-9844. 

Clay minerals or phyllosilicates are lamellar natural and synthetic materials with high surface area, cation exchange and swelling properties, exfoliation ability, variable surface charge density and hydrophobic/hydrophilic character [85], They are good host structures for intercalation or adsorption of organic molecules and macromolecules, particularly proteins. On the basis of the natural adsorption of proteins by clay minerals and various clay complexes that occurs in soils, many authors have investigated the use of clay and clay-derived materials as matrices for the immobilization of enzymes, either for environmental chemistry purpose or in the chemical and material industries. 

The main contributions to AadsG for a globular protein are from electrostatic, dispersion, and hydrophobic forces and from changes in the structure of the protein molecule. Although in this section these contributions are discussed individually, strict separation of the influence of these forces on the overall adsorption process of a protein is not possible. For instance, adsorption-induced alteration of the protein structure affects the electrostatic and hydrophobic interaction between the protein and the surface. When the sorbent surface is not smooth but is covered with (polymeric)... 

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