scholarly journals Relating Ion Binding by Fulvic and Humic Acids to Chemical Composition and Molecular Size. 1. Proton Binding

2001 ◽  
Vol 35 (13) ◽  
pp. 2860-2860 ◽  
Author(s):  
Iso Christl ◽  
Ruben Kretzschmar
Keyword(s):  
Chemical Composition ◽  
Humic Acids ◽  
Molecular Size ◽  
Ion Binding ◽  
Proton Binding

Relating Ion Binding by Fulvic and Humic Acids to Chemical Composition and Molecular Size. 2. Metal Binding

2001 ◽  
Vol 35 (12) ◽  
pp. 2512-2517 ◽  
Author(s):  
Iso Christl ◽  
Chris J. Milne ◽  
David G. Kinniburgh ◽  
Ruben Kretzschmar
Keyword(s):  
Chemical Composition ◽  
Humic Acids ◽  
Metal Binding ◽  
Molecular Size ◽  
Ion Binding

scholarly journals Relating Ion Binding by Fulvic and Humic Acids to Chemical Composition and Molecular Size. 2. Metal Binding

2001 ◽  
Vol 35 (13) ◽  
pp. 2860-2860 ◽  
Author(s):  
Iso Christl ◽  
Chris J. Milne ◽  
David G. Kinniburgh ◽  
Ruben Kretzschmar
Keyword(s):  
Chemical Composition ◽  
Humic Acids ◽  
Metal Binding ◽  
Molecular Size ◽  
Ion Binding

scholarly journals Kerogen nanoscale structure and CO2 adsorption in shale micropores

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Aleksandra Gonciaruk ◽  
Matthew R. Hall ◽  
Michael W. Fay ◽  
Christopher D. J. Parmenter ◽  
Christopher H. Vane ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Chemical Composition ◽  
Focused Ion Beam ◽  
Gas Adsorption ◽  
Ion Beam ◽  
Molecular Size ◽  
Gas Sorption ◽  
Nanoscale Structures ◽  
Adsorption Sites ◽  
Nanoscale Structure

AbstractGas storage and recovery processes in shales critically depend on nano-scale porosity and chemical composition, but information about the nanoscale pore geometry and connectivity of kerogen, insoluble organic shale matter, is largely unavailable. Using adsorption microcalorimetry, we show that once strong adsorption sites within nanoscale network are taken, gas adsorption even at very low pressure is governed by pore width rather than chemical composition. A combination of focused ion beam with scanning electron microscopy and transmission electron microscopy reveal the nanoscale structure of kerogen includes not only the ubiquitous amorphous phase but also highly graphitized sheets, fiber- and onion-like structures creating nanoscale voids accessible for gas sorption. Nanoscale structures bridge the current gap between molecular size and macropore scale in existing models for kerogen, thus allowing accurate prediction of gas sorption, storage and diffusion properties in shales.

Effect of extractant and molecular size on the optical and chemical properties of soil humic acids

Soil Research ◽  
1969 ◽  
Vol 7 (3) ◽  
pp. 229 ◽  
Author(s):  
JHA Butler ◽  
JN Ladd
Keyword(s):  
Molecular Weight ◽  
Amino Acid ◽  
Humic Acids ◽  
Gel Filtration ◽  
Chemical Properties ◽  
Molecular Size ◽  
Carboxyl Content ◽  
Peptide Bonds ◽  
Molecular Weights ◽  
Amino Acid Contents

Humic acids extracted from soil with sodium pyrophosphate have greater proportions of lower molecular weight material, less acid-hydrolysable amino acid nitrogen contents, but greater carboxyl contents and extinction values (260 and 450 nm) than humic acids extracted subsequently from the same sample with alkali. Humic acids extracted with alkali from fresh soil samples have intermediate values. Extinction values at 260 nm are directly correlated with carboxyl contents for a given soil. Different crop histories have no significant effect on the measured properties of the extracted humic acids. An alkali-extracted humic acid has been fractionated by gel filtration into seven fractions of different nominal molecular weight ranges. As the molecular weights of the fractions increase, both aliphatic C-H (based on infrared absorption at 2900 cm-1) and acid-hydrolysable amino acid contents increase, whereas extinction values at 260 nm and carboxyl contents decrease. The infrared spectra of the high molecular weight fractions have peaks at 1650 and 1510 cm-1 which correlate with acid-hydrolysable amino acid contents and which correspond to amide I and II bands of peptide bonds. Alkaline hydrolysis to split peptide bonds eliminates both these peaks. The spectra also have peaks at 1720 and 1210 cm-1 which correlate with the carboxyl content.

scholarly journals Isolation, chemical composition, and molecular size of extracellular type II and type Ia polysaccharides of group B streptococci.

1983 ◽  
Vol 41 (2) ◽  
pp. 527-534 ◽  
Author(s):  
B J De Cueninck ◽  
T F Greber ◽  
T K Eisenstein ◽  
R M Swenson ◽  
G D Shockman
Keyword(s):  
Chemical Composition ◽  
Molecular Size ◽  
Type Ii ◽  
Group B Streptococci ◽  
Type Ia ◽  
Group B

scholarly journals Molecular size distribution and hydrophilic and hydrophobic properties of humic acids isolated from forest soil

2008 ◽  
Vol 2 (No. 2) ◽  
pp. 45-53 ◽  
Author(s):  
B. Debska ◽  
M. Drag ◽  
M. Banach-Szott
Keyword(s):  
Humic Acids ◽  
Forest Soils ◽  
Tree Species ◽  
Plant Material ◽  
Molecular Size ◽  
European Beech ◽  
Plant Litter ◽  
Hydrophobic Properties ◽  
Degree Of Maturity ◽  
Molecular Size Distribution

The aim of the present paper was to determine hydrophilic and hydrophobic properties and the degree of polydispersity of humic acids depending on their degree of maturity and the properties of the plant material participating in the process of humification. The study involved humic acids isolated from samples taken from organic and mineral horizons of forest soils. The samples were taken under the tree stands of: pine with an admixture of hardbeam, European beech, elm, fir, spruce, and thuja. It was demonstrated that the properties of humic acids of the organic horizon and mineral horizons are determined by the kind of plant litter, mainly by the tree species. The humification process is connected with an increase of the proportion of humic acids of lower molecular size as compared to the proportion of molecules greater in size, and with an increase of hydrophilic fractions and a decrease of hydrophobic fractions. Based on the correlation relationships, it was shown that the degree of polydispersity of molecules of humic acids is related to their hydrophilic and hydrophobic properties. Humic acids with a larger proportion of high-molecular fractions demonstrate also a higher proportion of hydrophobic fractions.

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