Ability to sorb

The porosity and permeability of CP are the most important factors determining their ability to sorb and immobilize BAS. For solving these problems, it was necessary to synthesize various types of porous and permeable CP differing in the mobility of elements of the crosslinked structure and in the rigidity of the polymer backbone. For biological problems related to the application of CP as biosorbents, it has been found necessary to use CP with a marked structural inhomogeneity. 

Extracellular enzymes are rapidly sorbed at mineral and humic colloids in soils and sediments. Mineral colloids have a high affinity for enzymes although that is not always synonymous with the retention of their catalytic ability. On the other hand, humic substances have the ability to sorb and sequester enzymes in such a way as to retain their catalytic activity they could also strongly inactivate enzyme activity depending on interaction mechanisms. 

Microbial activity can also be stimulated by mineral colloids through their ability to sorb metabolites that would otherwise have an adverse effect on microbial growth (Filip et al. 1972 Filip and Hattori 1984) This may be due to the toxicity of metabolites, and their feed back repression and, encouraging competitors. Predictably, montmorillonite (CEC —100 cmol kg-1 and specific surface of 800 m g 1) is more effective than kaolinite and finely ground quarts. Other substances, such as antibiotics and pesticides that are toxic to some microorganisms, can also be adsorbed by the surfaces of mineral colloids (Theng and Orchard 1995 Dec et al. 2002). 

According to the calculations, the surface s ability to sorb cations and anions differs markedly between pH 4 and 8, reflecting both electrostatic influences and mass action. Nearly all of the sulfate is sorbed at pH 4, whereas most of the lead and... 

For now, we focus on bulk DOM parameters. Using pyrene as a common sorbate, 17 different DOMs were tested for their ability to sorb this PAH at 25°C. Correlations of the resultant KlD0C values with the bulk properties of the DOMs were then sought (Chin et al., 1997 Georgi, 1998). For pyrene sorption, the molar absorptivities at 280 nm (reflecting aromaticity) and the O/C ratio (reflecting overall polarity) were found to yield a significant correlation (Fig. 9.14) ... 

Zeolites display a number of interesting physical and chemical properties. The three classes of phenomena of greatest practical importance are the ability to sorb organic and inorganic substances, to act as cation exchangers, and to catalyze a wide variety of reactions. The most important aspects of these are described below. 

Several polymer properties are important in determining the ability to sorb vapors. The glass transition temperature, Tg, is the temperature at which a polymer changes from glassy to rubbery, as described in Chapter 4. Above Tg, (in the rubbery state), permeability is governed entirely by diffusional forces and sorption proceeds rapidly and reversibly. The sorption process is very much like absorption into a liquid and, as discussed later in the context of sorption mod-... 

Proteins sorb water molecules at low relative humidities through interactions at hydrophilic sites associated with the polar peptide bond and various polar side chains. A correlation of the polar amino acid content and ability to sorb water has been demonstrated for a series of soluble proteins by Bull (52). However, the influence of protein-protein interactions on the availability of particular polar groups complicates similar relationships for insoluble proteins such as keratin. 

This expression tells us that the precipitation of manganese oxides is favored by the presence of a pre-existing surface of manganese oxide or, as it turns out, of iron oxide. These oxide surfaces have the ability to sorb appreciable quantities of ions from solution, particularly favoring the cations of the transition metals. Oxidation of Mn involves, first, a sorption of the ion onto the oxide surface, followed by the oxidation step, hence the importance of a pre-existing surface. 

According to the calculations, the surface s ability to sorb cations and anions differs markedly between pH 4 and 8, reflecting both electrostatic influences and mass action. Nearly all of the sulfate is sorbed at pH 4, whereas most of the mercury remains in solution the opposite holds at pH 8. At pH 4, the surface carries a positive charge that attracts sulfate ions but repels mercury ions. The electrostatic effect is almost nil at pH 8, however, where the surface charge approaches zero. As well, the complexation reactions... 

The activity of some polyethylene glycols bonded with macroporous copolymers of glycidylmethacrylate during the interfacial catalysis of the model reaction of sodium phenolate with n-BuBr, were investigated [79]. Rate constants of phenol alkylation in the aqueous system NaOPh-n-BuBr (in toluene)-PEG were measured at 60°C as a function of the molecular weight of PEG and its concentration. The obtained results were compared with the data on the kinetics of the reaction occurring in the presence of soluble PEG. Upon the insertion of immobilized and soluble PEG, alkylation rates increased 168 and 139 fold, respectively. The increase of the catalytic activity of immobilized PEG, which corresponded to a rise in the molecular weight of the polymer, was caused by an increase in the PEG ability to sorb alkali metal cations. 

Evaluation of Inorganic Ion Exchangers. The materials In Table II were evaluated for their ability to sorb americium from both 0.25M oxalic acid and water, each adjusted to an Initial pH of 1.0. High distribution ratios under these conditions are essential to accomplish the Immobilization and disposal of americium. 

From the chemical standpoint a nucleus of an HDS particle is a three-dimensional polymer whose structural units are silicon-oxygen tetrahedra bonded by disiloxane bridges Si—O—Si. On the surface of HDS particles there are groups O—H chemically bonded with silicon atoms (silanol groups SiOH). The hydroxylic cover of HDS gives rise to a high hydrophilicity of its surface and, correspondingly, to its ability to sorb polar molecules. 

Dynamic reactions in the subsurface environment are critical in affecting the fate and transport of metals, as well as a number of other important processes (Figure 1). Soils and sediments have a remarkable ability to sorb metals. 

Stable nano/mesoporous materials with mixed oxides such as zeolites, clays, and other minerals are widely used in various fields catalysis, adsorption, ion-exchange, separation, etc. because of their catalytic activity in acid/base and redox (e.g., materials with titania phase) reactions, ability to sorb selective molecules of diverse types, participate in ion-exchange reactions, providing sieve effects, etc. (Tanabe 1970, Grandjean and Laszld 1989, Rocha and Anderson 2000, Cundy and Cox 2005, Tao et al. 2006). The most important processes that utilize the selective properties of these materials are alkylation and isomerization of aromatic hydrocarbons as well as conversion of methanol to hydrocarbons, and some other reactions. Silicalite is an extreme type of the materials with the ZSM-5 zeolite structure but whose aluminum content is negligible. Therefore, unlike conventional zeolites, silicalite does not possess ion-exchange properties, and its surface has a weak affinity to water. 

The ionic groups, although present in small amoimts, dominate the viscoelastic behavior of ionomers, their transport properties and their ability to sorb a variety of solvents moreover, the ion effect is specific. In terms of morphology, the presence of ions leads to microphase separation into ionic and nonpolar domains. Increasing interest in structural aspects of ionomers is closely related to their numerous applications as bulk materials, in various devices, as catalysts, in controlled release systems, and as proton exchange membranes (PEM) in fuel cells (71). 

QCM-, SAW-, and cantilever-based gas sensors are adsorption-type sensors in which the change in weight of the sensing element is the determining factor (Houser et al. 2001). Therefore, polymers applied in such devices should have the ability to sorb selectively and reversibly an analyte of interest from sampled air and to concentrate it so that lower concentrations can be detected. How specific adsorption properties of polymers can be, one can estimate on the base of results presented in Table 3.9. We need to note that for other analytes, polymers optimal for application will be different. 

A series of polysaccharide sorption power is similar for Pb and Cd and is as follows cellulose > pectin > starch > inulin [265]. It was shown in [262-265] that there is a correlation between the weight of the solid residue of the product made of vegetable raw and its ability to sorb lead and cadmium from the solutions of their salts. The larger the solid residue weight, the higher the sorption power of the product. In addition, a decrease in BAS particle sizes yields an increase in the sorption power. Interesting results were obtained in [262-265] when... 

Figure 7-12 is a comparison of the U(VI) sorptive behavior of three surface types. Sorption data are normalized to surface sites P = [U(VI)sorbed]/ [U(VI)soiu-tion] [colloid sites]. Note that (i) the surfaces dominate the sorption of U( VI) at different pH values and (ii) the surfaces are markedly different in their ability to sorb U(VI). Because the relative ability of a surface to compete against other sorbents for a radionuclide is a function of the product of the interaction parameter (e.g., P or and the site concentration (e.g., Eq. [2]), Fig. 7-12 suggests, for example, that Desulfovibrio vulgaris could be an effective colloidal transport agent at substantially lower concentrations than in the cases of the NOM and hematite. 

In brief, the tailored pore structure of electrospun nanoflbers endows the adsorbents the ability to sorb different adsorbates (formaldehyde, SO, benzene, hydrogen, etc.) in relatively high speed, and the large surface area ensures the high gas adsorption capacity. In further researches, the adsorption capacity, especially in humid conditions, should be promoted and the adsorb selectivity should be improved. Moving forward, electrospun nanoflbers could be potentially used to control and remove toxic gases for industry and potential inhabitant. 

Gelatin (GL) is a natural protein that is derived from collagen with many desirable properties for application as a biomaterial, including scaffolds for tissue engineering. Additionally, different kinds of GL carrier matrices can be employed as drug delivery devices, because of their ability to sorb biomolecules. As will be seen, depending on the fabrication method, variations in the... 

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