Adsorption isolation

Donor strengths, taken from ref. 207b, based upon the solvent effect on the symmetric stretching frequency of the soft Lewis acid HgBr2. Gutmann s donor number taken from ref 207b, based upon AHr for the process of coordination of an isolated solvent molecule to the moderately hard SbCL molecule in dichioroethane. ° Bulk donor number calculated as described in ref 209 from the solvent effect on the adsorption spectrum of VO(acac)2. Taken from ref 58, based on the NMR chemical shift of triethylphosphine oxide in the respective pure solvent. Taken from ref 61, based on the solvatochromic shift of a pyridinium-A-phenoxide betaine dye. 

To apply these various equations to the adsorption of a gas on a solid, it is necessary to consider the interaction of the surface layers of a solid composed of atoms (or ions) of a substance Y, say, with isolated molecules of gas X. The individual interactions of each atom in gas molecule X with each atom of the solid Y have to be added up to obtain the potential 0(z) of a single molecule of the gas with reference to the solid ... 

However, the quantity of Pa produced in this manner is much less than the amount (more than 100 g) that has been isolated from the natural source. The methods for the recovery of protactinium include coprecipitation, solvent extraction, ion exchange, and volatility procedures. AH of these, however, are rendered difficult by the extreme tendency of protactinium(V) to form polymeric coUoidal particles composed of ionic species. These caimot be removed from aqueous media by solvent extraction losses may occur by adsorption to containers and protactinium may be adsorbed by any precipitate present. 

The mixed monocyclic aromatics are called BTX as an abbreviation for ben2ene, toluene, and xylene (see Btxprocessing). The benzene and toluene are isolated by distillation, and the isomers of the xylene are separated by superfractionation, fractional crystallisation, or adsorption (see Xylenes and ethylbenzene). Bensene is the starting material for styrene (qv), phenol (qv), and a number of fibers and plastics. Toluene (qv) is used to make a number of... 

Isolation. Isolation procedures rely primarily on solubiHty, adsorption, and ionic characteristics of the P-lactam antibiotic to separate it from the large number of other components present in the fermentation mixture. The penicillins ate monobasic catboxyHc acids which lend themselves to solvent extraction techniques (154). Pencillin V, because of its improved acid stabiHty over other penicillins, can be precipitated dkecdy from broth filtrates by addition of dilute sulfuric acid (154,156). The separation process for cephalosporin C is more complex because the amphoteric nature of cephalosporin C precludes dkect extraction into organic solvents. This antibiotic is isolated through the use of a combination of ion-exchange and precipitation procedures (157). The use of neutral, macroporous resins such as XAD-2 or XAD-4, allows for a more rapid elimination of impurities in the initial steps of the isolation (158). The isolation procedure for cephamycin C also involves a series of ion exchange treatments (103). 

Pharmaceuticals. Pharmaceuticals account for 6% of the Hquid-phase activated carbon consumption (74). Many antibiotics, vitarnins, and steroids are isolated from fermentation broths by adsorption onto carbon foUowed by solvent extraction and distillation (82). Other uses in pharmaceutical production include process water purification and removal of impurities from intravenous solutions prior to packaging (83). 

Other immobilization methods are based on chemical and physical binding to soHd supports, eg, polysaccharides, polymers, glass, and other chemically and physically stable materials, which are usually modified with functional groups such as amine, carboxy, epoxy, phenyl, or alkane to enable covalent coupling to amino acid side chains on the enzyme surface. These supports may be macroporous, with pore diameters in the range 30—300 nm, to facihtate accommodation of enzyme within a support particle. Ionic and nonionic adsorption to macroporous supports is a gentle, simple, and often efficient method. Use of powdered enzyme, or enzyme precipitated on inert supports, may be adequate for use in nonaqueous media. Entrapment in polysaccharide/polymer gels is used for both cells and isolated enzymes. 

Another application shows the preparative purification and polishing of a therapeutic fusion protein with a humanized recombinant IgG protein. The fusion protein was expressed by the fermentation of baby hamster kidney cells. The filtered culture supernatant (155 liters) contained 2.2 g of IgG and 75.5 g of total protein. After the immunoglobulins were isolated by expanded bed adsorption and rebuffering, the IgG fraction was bound to Fractogel EMD SOj (M). This column achieved baseline separation of complete antibodies (fusion protein) from small amounts of antibodies lacking the fusion part. The resulting highly purified IgG fraction (110 ml) was diluted to 150 ml and... 

Neomycin has been produced by growing the organism, Streptomyces No. 3535, in a suitable nutrient medium under appropriate stationary or submerged aerobic (viz shaken) conditions, and then isolating and purifying the substance, e.g., by procedure of the sort described in the figure including various steps of adsorption, recovery by elution, separation from impurities, and precipitation. 

Figure 6.10b shows a pattern of antagonism often observed in isolated tissue studies but not so often in cell-based assays. Saturation of uptake systems for the agonist or saturation of an adsorption site for the agonist can account for this effect. The linear portion of the regression can be used to estimate the pKB or the pA2. If there is a loss of concentration dependence of antagonism, as seen in... 

Owing to the weak hydrophobicity of the PEO stationary phases and reversibility of the protein adsorption, some advantages of these columns could be expected for the isolation of labile and high-molecular weight biopolymers. Miller et al. [61] found that labile mitochondrial matrix enzymes — ornitine trans-carbomoylase and carbomoyl phosphate synthetase (M = 165 kDa) could be efficiently isolated by means of hydrophobic interaction chromatography from the crude extract. 

These sorbents may be used either for selective fixation of biological molecules, which must be isolated and purified, or for selective retention of contaminants. Selective fixation of biopolymers may be easily attained by regulation of eluent polarity on the basis of reversed-phase chromatography methods. Effective isolation of different nucleic acids (RNA, DNA-plasmid) was carried out [115, 116]. Adsorption of nucleosides, nucleotides, tRN A and DNA was investigated. It was shown that nucleosides and nucleotides were reversibly adsorbed on... 

The development and adaptation of procedures for the separation, isolation, purification, identification, and analysis of the components of the pyrethrum mixture have been studied and evaluated. Results of studies to determine the molar extinction coefficient of pyrethrin I as well as a gas chromatographic procedure for the determination of pyrethrins are reported. The use of chromatographic separation procedures (including partition, adsorption, gas, and thin-layer chromatography), colorimetry, and infrared spectrophotometry are discussed. 

The relation (13) for isolated reactions becomes identical with the expression (15) for coupled reactions when (/CaCa) = (KBcB) , while, on the other hand, the difference in the values of the expressions (13) and (15) will be the greater, the greater is the difference in the adsorptivity of sub-... 

In contrast to consecutive reactions, with parallel competitive reactions it is possible to measure not only the initial rate of isolated reactions, but also the initial rate of reactions in a coupled system. This makes it possible to obtain not only the form of the rate equations and the values of the adsorption coefficients, but also the values of the rate constants in two independent ways. For this reason, the study of mutual influencing of the reactions of this type is centered on the analysis of initial rate data of the single and coupled reactions, rather than on the confrontation of data on single reactions with intergal curves, as is usual with consecutive reactions. 

The values of the rate constants and adsorption coefficients obtained by the study of isolated reactions agreed well with those obtained by the study of parallel reactions (Table V). The three values of the adsorption coefficient of each acid were obtained independently. In addition to one value from the study of isolated reactions, two additional values were determined by the study of the parallel system one from the kinetics of the consumption of the given acid by reaction (Vila) or (Vllb), and one from the kinetics of reaction (Vile). 

The results obtained showed, again, that the form of the rate equations and the values of their constants, obtained by the study of isolated reactions, are valid also in the coupled system. This was also confirmed by the observed agreement between the calculated and the experimental integral data (94)- Kinetic results and the analysis of the effect of reaction products revealed that adsorption of the reaction components was competitive and that all the compounds involved in the three reactions were adsorbed on the same sites of the catalytic surface. 

A vapor phase process for deparaffmization of light gas oils performed by the BP works in this way The gas oil, boiling range 230-320°C, is passed over a 5-A molecular sieve at 320°C and a pressure of 3.6 bar. The space velocity is 0.63 vol liquid gas oil per vol molecular sieve and per hour, [liquid hourly space velocity (lhsv) = 0.63] the adsorption period takes 6 min. Together with the gas oil vapor 120 vol N2 per vol liquid gas oil is led over the sieve as carrier and purge gas. After the adsorption period the loaded molecular sieve is purged at the same temperature with pure N2 for 6 min. Subsequently, the adsorbed /z-alkanes are desorbed by 1 vol liquid /z-pentane per vol molecular sieve and per hour. The /z-pentane is recovered from the /z-alkane//z-pentane mixture by simple distillation [15]. The IsoSiv process of the Union Carbide Corporation works in a similar way [16]. The purity of the isolated /z-alkanes is >98%. 

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