Adsorptive abilities

Filter aids may be applied in one of two ways. The first method involves the use of a precoat filter aid, which can be applied as a thin layer over the filter before the suspension is pumped to the apparatus. A precoat prevents fine suspension particles from becoming so entangled in the filter medium that its resistance becomes exces-sive. In addition it facilitates the removal of filter cake at the end of the filtration cycle. The second application method involves incorporation of a certain amount of the material with the suspension before introducing it to the filter. The addition of filter aids increases the porosity of the sludge, decreases its compressibility, and reduces the resistance of the cake. In some cases the filter aid displays an adsorption action, which results in particle separation of sizes down to 0.1 /i. The adsorption ability of certain filter aids, such as bleached earth and activated charcoals, is manifest by a decoloring of the suspension s liquid phase. This practice is widely used for treating fats and oils. The properties of these additives are determined by the characteristics... 

Recently, Shimidzu etal.s7) studied the adsorption ability of cross-linked, ARPVP (31) resins toward mononucleotide in aqueous and pyridine media. They claimed that hydrogen-bonding was important between the resins and nucleotides under their conditions. 

The same concepts apply to column chromatography, where the stationary phase is normally small particles of silica, Si02, or alumina, A1,0 . These substances are not very reactive and have specially prepared surfaces to increase their adsorption ability. The column is saturated with solvent, and a small volume of solution containing the solutes is poured onto the top. As soon as it has soaked in, more solvent is added. The solutes travel slowly down the column and are eluted (removed as fractions) at the bottom (Fig. 2). If the mobile phase is less polar than the stationary phase, the less polar solutes will be eluted first and the more polar ones last. 

This mechanism has been probed by ab initio calculation.157 Structural modifications of the cyclam framework can drastically affect the catalytic efficiency, as a consequence of the modification of the metal ability to interact with C02 or of the modification of the adsorption ability of the complex.157-163 For instance it has been found that the increase of TV-methyl substitution of the cyclam increases the adsorption of the Ni11 complex on the mercury electrode, but decreases the stability of the Ni1 reduced form.164... 

The observed H2/CO effect on CO conversion can be explained considering the strong CO adsorption ability on cobalt-based catalysts. At the typical FT process conditions, in fact, it has been reported that the catalyst surface is almost... 

Table 1 summarizes a few properties of the resulting fibers used in studies on their metal ion adsorption abilities. Hereafter, bifucntional fibers derived from PPPE-c and PPPE-f are denoted by symbols FPS-c and FPS-f, respectively, and respective symbols FP-c and FP-f denote monofunctional... 

Egawa, H., Nonaka, T., Ikari, M., preparation of macroreticular chelating resins containing dihydroxyphosphino and/or phosphono groups and their adsorption ability for uranium. J. Appl. Polym. Sci. 29, 1984,2045-2055. 

Some data obtained from MCT, SFA, and TFB under similar conditions are compared in Fig. 2.20b. The SFA data were taken from reference [80]. They were obtained with hydrophobized mica surfaces, protein concentration of 0.1 wt%, and ionic strength of 10 mol/1. Data for TFB and MCT led to very similar results. However, comparison with the SFA data demonstrates that the force laws are only qualitatively similar the curves are parallel but the normalized data for liquid-liquid interfaces (TFB and MCT) lie about one decade below those obtained for solid-liquid interfaces (SFA). This result suggests that the proteins exhibit different adsorption abilities and or adopt different conformations at the two types of surfaces. 

New chelating polymers having high adsorption ability for uranium have been given much attention with respect to recovery and purification of uranium. The polymers having hydroxamic acid (24), amidoxime (25), dihydroxyphospino, or... 

A definite quantity of oxygen molecules accumulated on the surface of the biomimetic electrode (catalase reaction) must diffuse to the volume of the adhesive layer, toward the electrode surface. Hence, the specific requirements to the adhesive follow on the one hand, it must provide strong enough adhesion of a mimic to electrode on the other hand, it must possess low oxygen adsorption ability. 

OH anions, formed in electrode reaction (8.2), must display higher adsorption ability to the adhesive. 

Moreover, these in situ modified CMC/BC composites exhibit good ion-exchange capacities with specific adsorption ability for lead and uranyl ions. Their application to ion exchangers has been described [41]. 

Beside the chemical composition, the crystalline structure of the mineral has an important effect on the adsorption ability of its surface. This is due to the fact that lattice bindings are usually not equivalent and space disproportions occur, so that fission surface areas have specific properties. Typical examples are layer lattices of graphite or talc where the main valences proceed in the layer plains whereas these are interconnected with feeble valences. Fission areas of such minerals are hydrophobic. The effect of the structure on adsorption properties of a mineral surface increases with increasing adsorption density and with decreasing force of the adsorption binding of the solid phase5. A crystalline lattice contains structural defects (which include physical and chemical surface imperfections and deficiencies in the volume phase) which can influence the chemical reactivity of a crystal surface. 

For several reasons the mechanism and role of radicals must be discussed. First, the adsorption ability of the chloride ion is very low (Pleskov 2003). Second, not only chlorine but also other oxychlorine products such as chlorate and chlorine dioxide can be found by analysing the treated water and, chloride ions are able to react with other radicals formed by reaction of OH radicals with additional ions. This allows one to conclude that the formation of active chlorine proceeding with the participation of OH radicals [(7.12) and (7.13)] is likely. 

A wide range of plastics with different properties has been used in the construction of laboratory apparatus. In spite of the adsorption ability of the polymers and, therefore, the risk of analyte loss by adsorption on container walls, contamination arising from residual catalysts and additives used in their manufacture is the main problem. Among the most common plastics used in manufacturing laboratory containers are low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP) and polytetrafluoro-ethylene (PTFE). 

The affinity of DOM with soil was very low with an average DOM sorption percentage of about 22.4 4.8% to 31.2 +5.2% only at an initial DOC concentration of 100 mg/1 and 200 mg/1, respectively, for the live selected DOMs (Table 10.3). This result was supported by the small slope m of 0.11 to 0.24 and Kd of 0.47 to 1.23 ml/g obtained from the IM isotherms. Liang et al. (1996), who worked on a variety of soils with clay contents ranging from 3 to 54%, showed that the adsorption of the DOC by soils increased as the clay, organic matter contents, and the surface areas of the soils increased. The coarse texture of the selected calcareous soil and the characteristics of the selected DOM itself can explain the lower affinity of DOM with soil observed in the present study. In addition, the acidic soil with higher Fe-oxide and Mn-oxide content exhibited much higher DOC adsorption ability than calcareous soil rich in 2 1 minerals. 

Many experimental techniques are used to study the adsorption ability of fillers and the adsorption of polymer chains at surfaces. Different types of information are provided by these methods. 

Stress-strain curves for PDMS, containing different types of Aerosil, are compared in Fig. 14. As can be seen, the total interfacial area between Aerosil particles and elastomer matrix and/or the amount of filler and its adsorption ability are of great importance for the improvement of stress-strain characteristics,... 

A change in the hydrophilic nature of the polymer surface on irradiation of poly-(p-phenylazoacrylanilide) (PAAn) or its copolymer with HEMA may be used to control the adsorption — desorption behavior of proteins or organic substances onto the polymer [49]. Adsorption of lysozyme onto the copolymer of p-phenylazo-acrylanilide and HEMA was foimd to decrease from 4.6 eg to 1.8 eg per gram of adsorbent on ultraviolet irradiation, which induces the isomerization from the trans to the cis form. The decrease in adsorption ability upon ultraviolet irradiation is explained by a reduction of the hydrophobic interaction between the protein and the polymer, which results from the appearance of hydrophilic cw-form azobenzene on the surface. 

The activity of the zeolite-encapsulated catalysts were compared to the free complexes (Table 1). The specific activity of the encapsulated Fe-phthalocyanine catalyst was about four times higher than those of the free complex. A possible explanation for this observation is that the zeolite supercage has high adsorption ability, which can increase the concentration, and consequently the rate. 

Widely used as adsorbents and the components of catalysts synthetic zeolites are unique molecular sieve, which is defined by specify of their pore structure, namely, size and form of cavities of channels. During development of adsorbents and catalysts it is necessary to decide the tasks of saving of initial pore structure and connected with it adsorption ability of samples or of directed its changing with the purpose of increase of yield of necessary products, for example para - selectivity increase in the isomerisation of alkylaromatic compounds. The pore structure of zeolite-containing systems directly depends on cry stalline structure ones. 

In the present paper the change of cry stalline structure and adsorption ability of NaY zeolite is investigated with the purpose of obtaining from it the ultra stable form. An aqueous solution hexafluorosilicate is used as the agent of dealumination. 

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