Adsorptive characteristics

Protein adsorption has been studied with a variety of techniques such as ellipsome-try [107,108], ESCA [109], surface forces measurements [102], total internal reflection fluorescence (TIRE) [103,110], electron microscopy [111], and electrokinetic measurement of latex particles [112,113] and capillaries [114], The TIRE technique has recently been adapted to observe surface diffusion [106] and orientation [IIS] in adsorbed layers. These experiments point toward the significant influence of the protein-surface interaction on the adsorption characteristics [105,108,110]. A very important interaction is due to the hydrophobic interaction between parts of the protein and polymeric surfaces [18], although often electrostatic interactions are also influential [ 116]. Protein desorption can be affected by altering the pH [117] or by the introduction of a complexing agent [118]. 

Enzymes are important catalysts in biological organisms and are of increasing use in detergents and sensors. It is of interest to understand not only their adsorption characteristics but also their catalytic activity on the surface. The interplay between adsorption and deactivation has been clearly illustrated [119] as has the ability of a protein to cleave a surface-bound substrate [120]. 

PX is not separated via distillation because its boiling point is too close to that of MX. Instead, the differences in freezing points and adsorption characteristics are exploited commercially, as described in detail herein. 

Design data are available for the specific organics on the EPA s priority pollutant Hst. For mixed wastewaters, a laboratory study is necessary to determine adsorption characteristics. Wastewater is contacted with a range of concentrations of powdered carbon and adsorption occurs, as graphed ia the form of a Freundhch Isotherm, shown ia Figure 19. 

Several types of nitrogen substituents occur in known dye stmetures. The most useful are the acid-substituted alkyl N-substituents such as sulfopropyl, which provide desirable solubiUty and adsorption characteristics for practical cyanine and merocyanine sensitizers. Patents in this area are numerous. Other types of substituents include N-aryl groups, heterocycHc substituents, and complexes of dye bases with metal ions (iridium, platinum, zinc, copper, nickel). Heteroatom substituents directly bonded to nitrogen (N—O, N—NR2, N—OR) provide photochemically reactive dyes. 

Adsorbents Table 16-3 classifies common adsorbents by structure type and water adsorption characteristics. Structured adsorbents take advantage of their crystalline structure (zeolites and sllicalite) and/or their molecular sieving properties. The hydrophobic (nonpolar surface) or hydrophihc (polar surface) character may vary depending on the competing adsorbate. A large number of zeolites have been identified, and these include both synthetic and naturally occurring (e.g., mordenite and chabazite) varieties. 

Hydrated alumina is one of the most widespread hydrophilic polar sorbents for concentration and separation of different substances. In water Al Oj shows cation or anion exchange properties and its protolytic and adsorption characteristics depend on a way of obtaining. 

Foster, K. L., Fuerman, R. G., Economy, J., Larson, S. M. and Rood, M. J., Adsorption characteristics of trace volatile organic compounds in gas streams onto activated carbon fibers, Chem. Mater., 1992, 4(5), 1068 1073. 

The equilibrium adsorption characteristics of gas or vapor on a solid resemble in... 

Granular media filtration is used for treating aqueous waste streams. The filter media consists of a bed of granular particles (typically sand or sand with anthracite or coal). The anthracite has adsorptive characteristics and hence can be beneficial in removing some biological and chemical contaminants in the wastewater. This material may also be substituted for activated charcoal. 

In the following paper, the possibility of equilibration of the primarily adsorbed portions of polymer was analyzed [20]. The surface coupling constant (k0) was introduced to characterize the polymer-surface interaction. The constant k0 includes an electrostatic interaction term, thus being k0 > 1 for polyelectrolytes and k0 1 for neutral polymers. It was found that, theoretically, the adsorption characteristics do not depend on the equilibration processes for k0 > 1. In contrast, for neutral polymers (k0 < 1), the difference between the equilibrium and non-equilibrium modes could be considerable. As more polymer is adsorbed, excluded-volume effects will swell out the loops of the adsorbate, so that the mutual reorientation of the polymer chains occurs. 

On his return to Princeton after the war, Hugh Taylor organized catalytic research at the Frick Chemical Laboratory. He applied high vacuum technique, liquid air cryoscopy to the study of adsorptive characteristics of catalysts, correlating rates of catalytic reactions and rates of adsorption. He introduced the concept of activated adsorption and defended it against all comers. ... 

A fourth separation technique employs charcoal. Charcoal has adsorption characteristics such that most organic molecules will adhere to its surface. However, charcoal is also very porous, thereby allowing smaller molecules to enter into its pores and become trapped in them. The charcoal is first coated with dextran or hemoglobin which covers its outer surface. 

Extraction of rhizosphere soil (22,34,51,52) is an approach that can provide information about long-term accumulation of rhizosphere products (root exudates and microbial metabolites) in the soil. Culture systems, which separate root compartments from adjacent bulk soil compartments by steel or nylon nets (52-54) have been employed to study radial gradients of rhizosphere products in the root environment. The use of different extraction media can account for different adsorption characteristics of rhizosphere products to the soil matrix (22,34). However, even extraction with distilled water for extended periods (>10 min) may... 

Thus, all above experimental examples indicate that additionally to effect of disordering of the surface of adsorbent on its adsorption characteristics it is necessary to account for the effect of the adsorption itself on degree of adsorbent disordering controlling both its own electrophysical characteristics and the adsorption-caused change while deriving the theory of adsorption response of polycrystalline semiconductor adsorbent. 

It is not immediately obvious why the 3-isomer should be so reactive. The functional groups are meta-directing but are slightly deactivating however, the adsorption characteristics may play a large part in determining the reaction behaviour and these are reflected in the order of reaction. 

Chemical separations may first be accomplished by partitioning on the basis of polarity into a series of solvents from non-polar hexane to very polar compounds like methanol. Compounds may also be separated by molecular size, charge, or adsorptive characteristics, etc. Various chromatography methods are utilized, including columns, thin layer (TLC) gas-liquid (GLC), and more recently, high pressure liquid (HPLC) systems. HPLC has proven particularly useful for separations of water soluble compounds from relatively crude plant extracts. Previously, the major effort toward compound identification involved chemical tests to detect specific functional groups, whereas characterization is now usually accomplished by using a... 

In both cases, overall adsorption and especially that of sulfonate (or "primary surfactant in the composition of most micellar systems used for EOR) are considerably reduced by simply adding a second product having low adsorption characteristics (NP 30 EO in the above example). This is why we have called this strongly hydrophilic surfactant a desorbent. 

To establish the well drainage boundaries and fluid flow patterns within the TFSA-waterflood pilot, an interwell chemical tracer study was conducted. Sodium thiocyanate was selected as the tracer on the basis of its low adsorption characteristics on reservoir rocks (36-38), its low and constant background concentration (0.9 mg/kg) in produced fluids and its ease and accuracy of analysis(39). On July 8, 1986, 500 lb (227 kg) of sodium thiocyanate dissolved in 500 gal (1.89 m3> of injection brine (76700 mg/kg of thiocyanate ion) were injected into Well TU-120. For the next five months, samples of produced fluids were obtained three times per week from each production well. The thiocyanate concentration in the produced brine samples were analyzed in duplicate by the standard ferric nitrate method(39) and in all cases, the precision of the thiocyanate determinations were within 0.3 mg/kg. The concentration of the ion in the produced brine returned to background levels when the sampling and analysis was concluded. 

It is assumed that the reactive gas A has adsorption characteristics similar to those of the gas used in the pulse experiment. 

Cantarero, L.A., Butler, J.E., and Osborne, J.W. (1980) The adsorptive characteristics of proteins for polystyrene and their significance in solid-phase immunoassays. Anal. Biochem. 105, 375-382. 

Nelson YM, Lion LW, Ghiorse WC, Shuler ML (1999) Production of biogenic Mn oxides by Leptothrix discophora SS-1 in a chemically defined growth medium and evaluation of their Pb adsorption characteristics. Appl Environ Microbial 65 175-180... 

---