Surface Properties Chromatography

In the present work the acid-base surface properties of three Al O samples for a chromatography are investigated acidic (I), basic (II) and neutral (III) ones with the using of heterogeneous titration of their suspensions by HCl and NaOH solutions. To establish the correlations between the acid-base and adsoi ption properties studied Al O the representatives of cationic dyes -diamond green (DG), fuchsine (F) and anionic dyes - eriochrom black T and chromic dark blue have been used. 

It is generally desirable to integrate measurements representing a working catalyst surface with measurements that characterize the activity, selectivity, and/or stability of the catalyst, such as can be determined by use of gas chromatography or mass spectrometry of products. It is important to keep in mind that when a reactor is designed to serve optimally as a cell for measurements of catalyst surface properties, it may not be the kind of ideal reactor that would provide activity, selectivity, or stability data that can be interpreted fundamentally in terms of kinetics and chemical reaction engineering. 

Many different mobile phases have been utilized to provide the forward velocity for nonadsorbed molecules. If die mobile phase is a gas, then the technique used is gas chromatography (GC). In GC, die surface to which die molecules adsorb can be a wide variety of materials which are often prepared by coating an inert surface widi a polymer whose properties are related to its structure. In this way die surface properties and hence adsorption of die solid surface can be varied to give die best chromatographic resolution. 

Ticehurst MD, Rowe RC, York P. 1994. Determination of the surface properties of two batches of salbutamol sulphate by inverse gas chromatography. Int. J. Pharm. Ill ... 

Ticehurst MD, et al. 1996. Characterisation of the surface properties of alpha-lactose monohydrate with inverse gas chromatography, used to detect batch variation. Int. J. Pharm. 141 93-99. 

Zero Coverage. Inverse gas chromatography has been used successfully In the past decade for studying the surface properties of solids by adsorption of vapour at a gas-solid Interface. Unlike conventional adsorption techniques, IGC allows the measurement of adsorption data down to low vapour concentrations where the surface coverage approaches zero, adsorbate-adsorbate Interactions are negligible, and thermodynamic functions depend on only adsorbate-adsorbent Interactions. 

Determination of Surface Properties Using Inverse Gas Chromatography. 

Inverse gas chromatography at infinite dilution appears to be a powerful tool for studying the surface properties of carbon fibres and polymer matrices. The use of alkane probes and acid/base probes allows the characterization of the surfaces in terms of their London dispersive component of surface energy and their acid/base or acceptor/donor characteristics. A strong correlation was obtained between fibre-matrix adhesion, measured by a destructive fragmentation technique, and the level of acid base interactions calculated from the chromatographic analysis. 

Whereas conventional chromatographic methods manipulate the surface energetics of sorbents to separate fluid mixtures, inverse gas chromatography uses known properties of fluids to characterize surface properties of solids. Specifically, Lewis acids and bases are used, in this study, as probes to deduce the nature and extent of solid/gas attraction from the shape of chromatograms, which are transformed adsorption isotherms. IGC can determine the specific surface (m2/g) of the substrate, whether the surface is acidic, basic, amphoteric, or neutral, and whether the surface is homogeneous or heterogeneous. 

The examples given above indicate the necessity of having a better understanding of the surface properties of divided solids that have received a surface treatment. The objective of this paper is to demonstrate how advantageous inverse gas chromatography (IGC) is in achieving this goal. 

Papirer, E., Brendle, E., Ozil, F., and Balard, H. (1999). Comparison of the surface properties of graphite, carbon black and fiillerene samples, measured by inverse gas chromatography. Carbon, 37, 1265—74. 

Riddle FL, Fowkes FM. Special shifts in acid-base chemistry. 1. Van der Waals contributions to acceptor numbers. J Am Chem Soc 1990 112 3260-3264. Papirer E, Brendle E, Balard H, Vergelati C. Inverse gas chromatography investigation of the surface properties of cellulose. J Adhesion Sci Technol 2000 14 321-337. 

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