Hysteresis in Sorption. IV. Permanence and Scanning of the Hysteresis Loop. Silica Gel–Carbon Tetrachloride System.

1941 ◽  
Vol 45 (3) ◽  
pp. 517-521 ◽  
Author(s):  
Kittur Subba Rao
Keyword(s):  
Carbon Tetrachloride ◽  
Hysteresis Loop ◽  
Silica Gel

HYSTERESIS IN SILICA GEL SORPTION SYSTEMS

1934 ◽  
Vol 10 (6) ◽  
pp. 713-729 ◽  
Author(s):  
L. M. Pidgeon
Keyword(s):  
Hysteresis Loop ◽  
Silica Gel ◽  
Sulphur Dioxide ◽  
Water System ◽  
The Other ◽  
Vapor Pressures ◽  
Large Pressure ◽  
Pressure Changes ◽  
Permanent Gases ◽  
Sorption Systems

The hysteresis which normally appears in the isotherms of the silica gel-water system has been attributed by Patrick to the presence of permanent gases in the system. Only one case has been found in which a reversible isotherm has been recorded in the silica gel-water system. For alcohol and benzene only one case of hysteresis has been reported. These results seem to be independent of the presence or absence of air or other gases.The sorption of water, benzene and ethyl alcohol has been examined using the sorption balance. A hysteresis loop appears for water only. This hysteresis may not be eliminated by special methods of evacuation and must be considered as a real effect. The isotherms of alcohol and benzene, on the other hand, are completely reversible. It has been shown that the dimensions of the hysteresis occurring in the water system may be affected by the manner of addition of vapor to the apparatus. Only when the vapor pressures remain reasonably constant during sorption are the dimensions of the effect evident. If very large pressure changes take place the hysteresis may disappear.A comparison of the isotherms for water showing hysteresis, and those of the sulphur dioxide system (upon which the original suggestion as to the cause of hysteresis was based) show that there is not necessarily any relation between the two.

Desorption of Water, Methyl Alcohol and Carbon Tetrachloride from Silica-gel Surfaces

Nature ◽  
1963 ◽  
Vol 198 (4884) ◽  
pp. 988-989 ◽  
Author(s):  
B. B. DARLOW ◽  
R. A. ROSS
Keyword(s):  
Carbon Tetrachloride ◽  
Silica Gel ◽  
Methyl Alcohol

scholarly journals The sorption of propyl and butyl alcohols by silica gel

1935 ◽  
Vol 150 (869) ◽  
pp. 77-83 ◽  
Keyword(s):  
Hysteresis Loop ◽  
Silica Gel ◽  
Ferric Oxide ◽  
Catalytic Decomposition ◽  
Butyl Alcohol ◽  
Silica Gels ◽  
Relative Pressure ◽  
Tertiary Butyl ◽  
Two Samples ◽  
Important Evidence

Isothermals of the aliphatic alcohols, from methyl to n -butyl, have been determined on ferric oxide gel, and the isothermals of methyl and ethyl alcohol on two samples of silica gel have also been investigated by the author. One of these silica gels, “gel A,” gave isothermals which were completely reversible, but the other, “ gel B,” showed a small hysteresis loop just before the saturation point was reached. The present paper deals mainly with further experiments on the latter specimen, using normal and iso-propyl alcohols, and normal butyl alcohol. An attempt to determine isothermals of tertiary butyl alcohol was unsuccessful owing to catalytic decomposition of the alcohol in contact with the gel. The same peculiarities which were observed with the lower alcohols have been found to persist throughout the series. The relative pressure at which the hysteresis loop occurs diminishes as the series is ascended, but the capillary radius calculated by means of the Kelvin equation remains constant, as has been found with ferric oxide gel. The data provide important evidence of the validity of this equation for comparative purposes, even when the calculated radii are extremely low.

Thin Layer Chromatographic Determination of Aflatoxins in Dry Ginger Root and Ginger Oleoresin

1980 ◽  
Vol 63 (5) ◽  
pp. 1052-1054 ◽  
Author(s):  
Mary W Trucksess ◽  
Leonard Stoloff
Keyword(s):  
Carbon Tetrachloride ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Silica Gel ◽  
Fish Meal ◽  
Chromatographic Determination ◽  
Adsorption Column ◽  
Mixed Feeds ◽  
Layer Chromatography

Abstract A method for determining aflatoxins in dry ginger root and ginger oleoresin, using 1-dimensional thin layer chromatography (TLC) for the determinative step, has been developed. The key cleanup steps that permit this change from the 2-dimensional TLC previously required are partitioning of the extract with carbon tetrachloride and use of an improved eluting system for the silica gel adsorption column. Recoveries of aflatoxins B1, B2, G1, and G2 added to samples of ground ginger were 82, 101, 106, and 110%, respectively; recoveries of these aflatoxins added to ginger oleoresin were 75, 100, 93, and 125%, respectively. The method is applicable to fish meal and a number of mixed feeds.

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