Physical Adsorption column

A variety of procedures were utilized to analyze this reaction mixture and to characterize a,10-diaminopolystyrene. Thin layer chromatographic analysis using toluene as eluent exhibited three spots with Rf values of 0.85, 0.09, and 0.05 which corresponded to polystyrene, poly(styryl)amine and a,w-diaminopolystyrene (see Figure 1). Pure samples of each of these products were obtained by silica gel column Chromatography of the crude reaction mixture initially using toluene as eluent [for polystyrene and poly(styryl)amine] followed by a methanol/toluene mixture (5/100 v/v) for the diamine. Size-exclusion chromatography could not be used to characterize the diamine since no peak was observed for this material, apparently because of the complication of physical adsorption to the column packing material. Therefore, the dibenzoyl derivative (eq. 5) was prepared and used for most of the analytical characterizations. 

Amount of ethene at column exit Ethene generated via metathesis with no physical adsorption effects... 

Neutral organic compounds that cannot exist as cations may be retained by physical adsorption but can be washed off the cation exchange colunm by a brief rinse with an organic solvent. The amine cation can then be eluted from the column with a 1 M solution of trimethylamine in methanol. The trimethylamine converts the amine cation to the free amine which is no longer retained by the cation exchanger. Because of its volatility, trimethylamine is easily removed from the eluate. After acidification, the sample amines can be separated by cation chromatography. 

From amongst the numerous applications of adsorption column chromatography, an interesting example is provided by the separation of a mixture of two enantiomers into its constituents whose separation cannot be carried out by the other usual physical methods like fractional crystallization or fractional distillation. A well-known illustration of the separation of enantiomers without their having to be converted into diastereoisomers by chemical reaction with optically active acids is the resolution of Troger s base, effected by V. Prelog and P. Wieland in 1944,... 

Preparation of active, insoluble enzymes by physical adsorption to matrices has already been discussed (see p. 362), and, in the case of polysaccharide matrices, most of the enzyme derivatives formed in this way depend upon ionic interaction between charged groups on the polysaccharide and enzyme (see Table II). The instability of these enzyme derivatives may be lessened by cross-linking the coupled enzyme molecules.A few enzymes have been insolubilized by inclusion in microcapsules of collodion, or by entrapment in a polysaccharide gel. - A partition eflFect, in which an enzyme is held in the aqueous phase of a cellulose column while the substrate flows through in an organic phase, has also been used. 

Similar to the partitioning in the water column, SVOCs can also partition through an absorption process in addition to physical adsorption onto the surface of particles. SVOCs would dissolve in the organic matter (OM) in the atmosphere, which exists both as primary (POA) and as secondary organic aerosols (SOA) (Lohmann and Lammel 2004). Kqa absorption model has been proposed by Pankow (1994) and Finizio et al. (1997). The octanol-air partitioning coefficient (Kqa) can be used to predict Kp with the assumption that the predominant distribution process is absorption (Harner and Bidleman 1998). The relationship between Kp and Kqa is... 

The adsorption separation processes are widely used in industry, particularly in oil refineries and petrochemical industries (Ruthven, 1984). Knowledge of physical and chemical principles in which they are inserted adsorptive processes is fundamental to the interpretation of adsorption phenomena. The kinetic aspects and the adsorption equilibrium form the theoretical basis for understanding between the fundamental principles and industrial practices. These parameters are therefore essential to the analysis and interpretation of experimental data serving as a support for the dynamic study of the adsorption columns. 

The cation-exchange resin used in this operation should be a macroporous rather than a microporous polymer to minimize physical adsorption. An intermediate exchange capacity (-0.6-1.2 mequiv g ) is required and the column dimensions should be small to avoid use of an excessive amount of trimethyl-amine-methanol solution to neutraUze the resin s H capacity in the elution step. 

A problem that has plagued GC from its beginning has been the physical adsorption of polar or polarizable analyte species, such as alcohols or aromatic hydrocarbons, on the silicate surfaces of column packings or capillary walls. Adsorption causes distorted peaks, which arc broadened and often exhibit a tail (recall Figure 26-5). Adsorption occurs with silanol groups that form on the surface of silicates by reaction with... 

Enzymes have been immobilized by covalent binding to polymeric supports, by entrapment in cross-linked polymer gels or by physical adsorption on to suitable materials such as ion-exchangers, with retention of activity. The first example of an industrially useful application of this technique was in the separation of L-amino acids from racemic mixtures. This procedure used the enzyme aminoacylase which is immobilized in suitable columns. The racemic amino acid mixture is acylated chemically to form a-N-acetyl-OL-amino acids. When this is passed through the column, only the N-acetyl-L-amino acids are deacylated by the enzyme and the resulting L-amino acids can then be purified. 

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