ADSORPTIVE AND GAS CHROMATOGRAPHIC PROPERTIES OF VARIOUS CATIONIC FORMS OF ZEOLITE X

1964 ◽  
Vol 42 (10) ◽  
pp. 2340-2350 ◽  
Author(s):  
H. W. Habgood
Keyword(s):  
Ionic Radius ◽  
Adsorption Process ◽  
Divalent Cations ◽  
Chromatographic Retention ◽  
Monovalent Cations ◽  
Zeolite X ◽  
Heats Of Adsorption ◽  
Quadrupole Interactions ◽  
Silver Compound ◽  
Retention Volumes

Gas chromatographic retention volumes for O2, N2, CH4, C2H6, C3H8, C4H10, C2H4, and C3H6 have been measured over a range of temperatures between 25 and 400 °C, on columns of the following ion-exchanged forms of zeolite X: Li+, Na+, K+, Mg++, Ca++, Ba++, and Ag+. In addition, for AgX zeolite, full isotherms have been determined for O2, N2, C2H6, and C2H4; and for NaX zeolite, isotherms for C2H6 and C2H4. The gas chromatographic retention volumes agree well with the isotherms in the case of NaX but are significantly low for AgX, presumably as the result of at least a portion of the adsorption process being slow. The heats of adsorption on NaX agree well with literature values for O2, N2, CH4, and C2H6 but are low for C3H8 and C4H10; further indication of slow processes and hence of a limitation of the g.c. technique. The observations can be correlated qualitatively in terms of the interplay of the following effects: (a) cationic field increases with decreasing ionic radius; (b) shielding of smaller cations is greater—at least in the six-membered oxygen-ring sites; (c) divalent cations, while having greater fields, are only half the number of monovalent cations and tend to be found in less exposed sites; and (d) the polarizing power of silver ion, which also occupies all types of exposed sites, is very strong. The most intense interactions were found with AgX; with ethylene a much stronger complex is formed than has been reported for any other silver compound. The significance of molecular quadrupole interactions on these heteroionic surfaces is shown by the much weaker cationic effects observed with O2 (which has negligible quadrupole moment) than with nitrogen.

Surface adsorption at low coverage of n-alkanes on bleached kraft papers using gas chromatography

1987 ◽  
Vol 65 (8) ◽  
pp. 1935-1939 ◽  
Author(s):  
N. Gurnagul ◽  
D. G. Gray
Keyword(s):  
Gas Chromatography ◽  
Free Energy ◽  
Surface Coverage ◽  
Surface Adsorption ◽  
Standard Free Energy ◽  
Chromatographic Retention ◽  
Heats Of Adsorption ◽  
Retention Volumes ◽  
Low Coverage ◽  
Entropy Of Adsorption

The adsorption at low surface coverage of a series of n-alkanes on various bleached kraft paper surfaces was measured by gas chromatography. Differences in surface area of the paper samples were readily measured from the gas chromatographic retention volumes. The standard free energy, the enthalpy, and the entropy of adsorption varied linearly with the number of carbon atoms in the n-alkanes. The heats of adsorption were close to the heats of liquefaction, indicating the non-specific interactions of the hydrocarbons with the bleached kraft surfaces. The London component of the surface free energy was estimated from the gas chromatographic results to be 47.9 mN/m.

Cation exchange in cell walls of gram-positive bacteria

1976 ◽  
Vol 22 (7) ◽  
pp. 975-982 ◽  
Author(s):  
Robert E. Marquis ◽  
Kathleen Mayzel ◽  
Edwin L. Carstensen
Keyword(s):  
Cation Exchange ◽  
Cell Walls ◽  
Divalent Cations ◽  
Teichoic Acid ◽  
Dry Weight ◽  
High Ionic Strength ◽  
Monovalent Cations ◽  
Anionic Sites ◽  
Gram Positive Bacteria ◽  
Anionic Groups

The relative affinities of various cations for anionic sites in isolated, bacterial cell walls were assessed by means of a technique involving displacement of one cation by another. The affinity series determined was [Formula: see text]. High affinity was correlated with low mobility of the bound ions in an electric field. The net cation-exchange capacities of walls isolated from a variety of bacteria were estimated by preparing the magnesium forms of the walls, washing them well with deionized water to remove supernumerary ions, and then completely displacing the magnesium with Na+ or H+. Total amounts of magnesium displaced varied from 73 μmol per gram dry weight, for walls of the teichoic acid-deficient 52A5 strain of Staphylococcus aureus to about 520 μmol per gram for Bacillus megaterium KM walls. The amount of displacable magnesium was inversely related to the physical compactness of the walls, except for walls of Streptococcus mutans GS-5. It was found that magnesium or calcium ions can each neutralize, or pair with, two anionic groups in walls suspended in ion-deficient media. Previous work had indicated that these ions may pair with only one anionic group at high ionic strength. Therefore, it appeared that there is a great deal of flexibility in the arrangement of charged groups in the wall. It was concluded also that for cells growing in commonly used laboratory media, which generally contain large excesses of monovalent versus divalent cations, there is a mix of small, cationic counterions in the wall and that monovalent cations may predominate even though the wall has higher affinity for divalent ions.

scholarly journals Zeolites as alcohol adsorbents from aqueous solutions

2006 ◽  
pp. 83-87 ◽  
Author(s):  
Blagica Cekova ◽  
Dragi Kocev ◽  
Elena Kolcakovska ◽  
Daniela Stojanova
Keyword(s):  
Heat Treatment ◽  
Aqueous Solutions ◽  
Pore Volume ◽  
Industrial Wastewater ◽  
Organic Molecules ◽  
Adsorption Process ◽  
Aqueous Acetone ◽  
Heats Of Adsorption ◽  
Series Of Experiments ◽  
Low Costs

The potential usage of zeolites as adsorbents for the removal of organic molecules from water was investigated in a series of experiments with aqueous solutions of lower alcohols. This could represent a simple solution to the problem of cleaning up industrial wastewater as well as recovering valuable chemicals at relatively low costs. Adsorption isotherms of the Langmuir type were applied, and calculations showed that the amount of propanol adsorbed on silicalite corresponded to approximately 70% of the pore volume. The adsorption process is simple, and recovery of the more concentrated products is easily done by heat treatment and/or at lowered pressures. Adsorption experiments with aqueous acetone showed that silicalite had approximately the same adsorption capacity for acetone as for n-propanol. Heats of adsorption were determined calorimetrically.

The role of sodium chloride in the process of induction by lithium chloride in cells of the Rana pipiens gastrula

Development ◽  
1968 ◽  
Vol 19 (3) ◽  
pp. 387-396
Author(s):  
Lester G. Barth ◽  
Lucena J. Barth
Keyword(s):  
Sodium Chloride ◽  
Culture Medium ◽  
Rana Pipiens ◽  
Divalent Cations ◽  
Pigment Cells ◽  
Distilled Water ◽  
Sodium Ions ◽  
Monovalent Cations ◽  
High Concentration

A study of the effects of a series of monovalent cations, Li+, Na+ and K+, and a series of divalent cations, Mn2+, Ca2+ and Mg2+, upon small aggregates of cells taken from the presumptive epidermis of Rana pipiens gastrulae revealed that these ions induce nerve and pigment cells (Barth, 1965). The effectiveness of both series of ions as inductors was similar to their effects on decreasing the electrophoretic mobility of DNA as determined by Ross & Scruggs (1964). When it was found that sucrose in glass-distilled water also would induce nerve and pigment cells the role of ions as inductors came under closer scrutiny. A study of the nature of the induction by sucrose revealed that a relatively high concentration of sodium ions was necessary in the culture medium used after sucrose treatment (Barth, 1966).

Effect of Silica Flour in Dow Corning High Vacuum Grease on Gas Chromatographic Retention Volumes

1961 ◽  
Vol 33 (11) ◽  
pp. 1625-1626 ◽  
Author(s):  
E. D. Smith
Keyword(s):  
High Vacuum ◽  
Chromatographic Retention ◽  
Retention Volumes

scholarly journals How does ryanodine modify ion handling in the sheep cardiac sarcoplasmic reticulum Ca(2+)-release channel?

1994 ◽  
Vol 104 (3) ◽  
pp. 425-447 ◽  
Author(s):  
A R Lindsay ◽  
A Tinker ◽  
A J Williams
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Relative Permeability ◽  
Single Channel ◽  
Divalent Cations ◽  
Monovalent Cations ◽  
Channel Conductance ◽  
Single Channel Conductance ◽  
Release Channel ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Conduction Pathway

Under appropriate conditions, the interaction of the plant alkaloid ryanodine with a single cardiac sarcoplasmic reticulum Ca(2+)-release channel results in a profound modification of both channel gating and conduction. On modification, the channel undergoes a dramatic increase in open probability and a change in single-channel conductance. In this paper we aim to provide a mechanistic framework for the interpretation of the altered conductance seen after ryanodine binding to the channel protein. To do this we have characterized single-channel conductance with representative members of three classes of permeant cation; group 1a monovalent cations, alkaline earth divalent cations, and organic monovalent cations. We have quantified the change in single-channel conductance induced by ryanodine and have expressed this as a fraction of conductance in the absence of ryanodine. Fractional conductance seen in symmetrical 210 mM solutions is not fixed but varies with the nature of the permeant cation. The group 1a monovalent cations (K+, Na+, Cs+, Li+) have values of fractional conductance in a narrow range (0.60-0.66). With divalent cations fractional conductance is considerably lower (Ba2+, 0.22 and Sr2+, 0.28), whereas values of fractional conductance vary considerably with the organic monovalent cations (ammonia 0.66, ethylamine 0.76, propanolamine 0.65, diethanolamine 0.92, diethylamine 1.2). To establish the mechanisms governing these differences, we have monitored the affinity of the conduction pathway for, and the relative permeability of, representative cations in the ryanodine-modified channel. These parameters have been compared with those obtained in previous studies from this laboratory using the channel in the absence of ryanodine and have been modeled by modifying our existing single-ion, four-barrier three-well rate theory model of conduction in the unmodified channel. Our findings indicate that the high affinity, essentially irreversible, interaction of ryanodine with the cardiac sarcoplasmic reticulum Ca(2+)-release channel produces a conformational alteration of the protein which results in modified ion handling. We suggest that, on modification, the affinity of the channel for the group 1a monovalent cations is increased while the relative permeability of this class of cations remains essentially unaltered. The affinity of the conduction pathway for the alkaline earth divalent cations is also increased, however the relative permeability of this class of cations is reduced compared to the unmodified channel. The influence of modification on the handling by the channel of the organic monovalent cations is determined by both the size and the nature of the cation.(ABSTRACT TRUNCATED AT 400 WORDS)

Interaction of lipids with intestinal brush border membrane preparations

1982 ◽  
Vol 60 (9) ◽  
pp. 904-909 ◽  
Author(s):  
P. Proulx ◽  
J. McNeil ◽  
I. Brglez ◽  
D. G. Williamson
Keyword(s):  
Brush Border ◽  
Protein Concentration ◽  
Brush Border Membrane ◽  
Divalent Cations ◽  
Monovalent Cations ◽  
Intestinal Brush Border Membrane ◽  
Intestinal Brush Border ◽  
Ph Range ◽  
Assay Conditions ◽  
Lipid Structures

Conditions for uptake of lipids by rabbit intestinal brush border membrane preparations were investigated. A variety of lipids were found to be incorporated, including choline and ethanolamine phosphatides as well as cholesterol, diglyceride, and fatty acid. The incorporation of those lipids tested was enhanced by Ca2+ and other divalent cations but not by monovalent cations. The optimal Ca2+ concentration was approximately 10 mM. The uptake varied with lipid and membrane protein concentration and proceeded at rates which were too rapid to measure under several assay conditions tried. Incorporations were decreased substantially outside the pH range of 6.5–8.0. The effect of one lipid, phosphatidylcholine, on the structural appearance of the membrane fraction was examined by electron microscopy. No free or surface-bound lipid structures could be detected and the membrane fractions appeared to be unchanged after uptake.

Effect of the polymer glass transition on the chromatographic retention volumes

2005 ◽  
Vol 97 (3) ◽  
pp. 793-796
Author(s):  
J. S. Vrentas ◽  
C. M. Vrentas
Keyword(s):  
Glass Transition ◽  
Chromatographic Retention ◽  
Polymer Glass ◽  
Retention Volumes

Tests of the Consistency between Binary Gas Adsorption Isotherms and Binary Chromatographic Retention Volumes

2000 ◽  
Vol 39 (5) ◽  
pp. 1514-1519 ◽  
Author(s):  
Mark J. Heslop ◽  
Bryan A. Buffham ◽  
Geoffrey Mason
Keyword(s):  
Adsorption Isotherms ◽  
Gas Adsorption ◽  
Chromatographic Retention ◽  
Retention Volumes
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