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

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.

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

Soil Research ◽

10.1071/sr9690229 ◽

1969 ◽

Vol 7 (3) ◽

pp. 229 ◽

Cited By ~ 50

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.

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Quantitation of apo-, mono-, and diferric transferrin by polyacrylamide gradient gel electrophoresis in patients with disorders of iron metabolism

Blood ◽

10.1182/blood.v66.6.1445.bloodjournal6661445 ◽

1985 ◽

Vol 66 (6) ◽

pp. 1445-1451

Author(s):

SC DiRusso ◽

IJ Check ◽

RL Hunter

Keyword(s):

Metal Binding ◽

Chronic Renal Disease ◽

Molecular Size ◽

Deficiency Anemia ◽

Electrophoretic Method ◽

Normal Individuals ◽

Gradient Gel Electrophoresis ◽

Menstruating Women ◽

Predicted Values ◽

Diferric Transferrin

We have developed a polyacrylamide gradient gel electrophoretic method to quantitate apo-, mono-, and diferric transferrin based upon differences in their molecular size. Purified transferrin saturated to different extents (3% to 98%) with iron showed proportions of the three forms as predicted from an approximately random distribution of iron between the two metal-binding sites. The iron distributions in sera of 14 normal individuals similarly correlated with the predicted values. In contrast, 22 of 43 patients with diseases associated with abnormalities in iron or transferrin metabolism had a disproportionate increase in monoferric transferrin. This abnormality occurred in seven of nine patients who had received bone marrow transplants, seven of 14 with chronic liver disease, and eight of nine menstruating women with probable iron deficiency anemia. Interestingly, 11 patients with malabsorption or chronic renal disease had normal iron distributions. The finding of abnormal distributions of iron on transferrin suggests that gradient gel analysis may be a useful tool for studying the physiologic mechanisms controlling iron utilization.

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

Infection and Immunity ◽

10.1128/iai.41.2.527-534.1983 ◽

1983 ◽

Vol 41 (2) ◽

pp. 527-534 ◽

Cited By ~ 1

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

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Isolation of humic acid from oxidized lignite and complexation with metal cations

Hemijska industrija ◽

10.2298/hemind160628041c ◽

2017 ◽

Vol 71 (4) ◽

pp. 319-327

Author(s):

Benjamin Catovic ◽

Minela Sisic ◽

Majda Srabovic ◽

Melita Huremovic

Keyword(s):

Humic Acid ◽

Metal Ions ◽

Humic Acids ◽

Metal Binding ◽

Base Material ◽

Metal Cations ◽

Biological Properties ◽

Metal Nitrate ◽

Chemical Difference ◽

The Difference

Lignite is brown coal, which in its composition contains humic acids. Humic acids are produced by coal combustion, which leads to the enrichment of coal humic acids. Lignite, from the opet pit mine Sikulje, lignite ore ?Kreka?, Bosnia and Herzegovina, was fragmented and sieved to the appropriate size and used as a base material. The isolation of humic acid was carried out from pre-oxidized and dried lignite after which it was refined. Identification thus obtained humic acids was carried out by FTIR spectroscopy and its characterization of UV analysis which is determined by optical density of isolated humic acid and its complexation with metal cations. Data obtained by FTIR spectroscopic analysis of isolated humic acids show no significant structural and chemical difference in relation to the spectrum obtained for standard humic acids (Sigma Aldrich). UV analysis showed that isolated and standard humic acid have E4/E6 ratio in an appropriate range of 3?5, which indicates the presence of a large number of aliphatic structure. Based on the degree of humification was found that the isolated humic acids belong to the type B standard while humic acids belong to type A. The most important property of the humic substances is the ability to interact with the metal ions forming soluble or insoluble complexes which possess different chemical and biological properties and stability. The nature of the complex between humic acid and metal cation derived from the heterogeneous, polyelectric and polydispersive character humic acids that occurs due to the presence of a large number of functional groups. Complexation of humic acid is carried out with different concentrations of metal nitrate solutions and at different pH values. Different amounts of humic acids were used for the complexation. The amount of the free metal ions was measured with the ICP-OES methode. The data were also statistically analyzed with ANOVA. The results showed that increasing the pH reduces the concentration of metal ions adsorbed on humic acid and by increasing the concentrations and amounts of metal humic acid that power increases. On the basis of the difference in absorbance between metals and humic acids can be said that there is an interaction between the metal and the ligand and is based on absorbance values obtained can be determine the next set of metal binding to humic acids Pb>Zn>Ni>Cu.

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