scholarly journals EXTRACTION OF HUMIC ACID BY ALKALI AND CHELATING RESIN

1972 ◽  
Vol 52 (3) ◽  
pp. 365-374 ◽  
Author(s):  
MARIA ORTIZ DE SERRA ◽  
M. SCHNITZER
Keyword(s):  
Humic Acid ◽  
Humic Acids ◽  
Structural Changes ◽  
Functional Group ◽  
Group Analysis ◽  
Chestnut Soil ◽  
Oxidation Products ◽  
Chelating Resin ◽  
Spectroscopic Methods ◽  
Permanganate Oxidation

Humic acid was extracted from the A1 horizon of a Dark Chestnut soil (pH = 6.9) with 0.5 N NaOH after decalcification and with Na-Dowex A-1 resin without decalcification. The two humic acids were characterized by chemical and spectroscopic methods and by permanganate oxidation after methylation. Whereas ultimate, functional group, and infrared analyses showed the two humic acids to be very similar, permanganate oxidation indicated a number of differences between the two preparations. The yield of oxidation products from the resin-extracted humic acid was twice as high as that from the alkali-extracted material. In addition, the resin-extracted humic acid produced appreciably larger amounts of high-molecular weight phenolic and benzenecarboxylic acids than did the alkali-extracted humic acid. These findings, in conjunction with E4/E6 ratios, indicated that the chelating resin-extracted humic acid was more condensed or less degraded than that removed by alkali. Permanganate oxidation of methylated humic substances appears to be a more sensitive technique for uncovering structural changes in such materials than are functional group analysis and spectroscopic methods.

scholarly journals Anti-HSV-1 Activity of Synthetic Humic Acid-Like Polymers Derived from p -Diphenolic Starting Compounds

2002 ◽  
Vol 13 (4) ◽  
pp. 241-249 ◽  
Author(s):  
R Klöcking ◽  
B Helbig ◽  
G Schötz ◽  
M Schacke ◽  
P Wutzler
Keyword(s):  
Humic Acid ◽  
Functional Group ◽  
Group Analysis ◽  
Vero Cells ◽  
Oxidation Products ◽  
Cytotoxic Activities ◽  
Hydroxyl Groups ◽  
Molecular Weights ◽  
Functional Group Analysis ◽  
Hsv 1

A panel of ten humic-acid-like polymers was synthesized by oxidation of p -diphenolic compounds and characterized by relative molecular weights, FT-IR spectra and functional group analysis. Using the XTT-based tetrazolium reduction assay EZ4U, both the low-molecular starting compounds and the synthesized polymers were examined for antiviral and cytotoxic activities in HSV-1-infected Vero cells. With the exception of hydroquinone, 2,5-dihydroxytoluene and 2,5-dihydroxybenzoquinone, the starting compounds failed to inhibit herpesvirus replication. The polymeric oxidation products, however, developed anti-HSV-1 activity with EC50 values in the range of 0.65 (2,5-DHPOP) and 322 μg/ml (2,5-DHBQOP). The CC50 values of the polymers varied among 32.0 (TMHYDROP) and >512 μg/ml (2,5-DHBQOP, HYDSULFOP). The most effective polymers were found to be 2,5-DHPOP, 2,5-DHTOP and GENOP (EC50: 0.65, 1.6 and 2.2 μg/ml, respectively, and SI: ≥400, ≥80 and ≥58, respectively). Functional group analysis revealed that increasing numbers of carboxyl groups together with a high content of hydroxyl groups tend to enhance the antiviral activity of polymers derived from p -diphenolic compounds.

scholarly journals Redox index of soil carbon stability

2010 ◽  
Vol 34 (5) ◽  
pp. 1543-1551 ◽  
Author(s):  
Marihus Altoé Baldotto ◽  
Maria Cristina Canela ◽  
Luciano Pasqualoto Canellas ◽  
Leonardo Barros Dobbs ◽  
Ary Carlos Xavier Velloso
Keyword(s):  
Humic Acid ◽  
Humic Acids ◽  
Salt Effect ◽  
Spectroscopic Methods ◽  
Weathering Index ◽  
Organic C ◽  
Exchangeable Ca ◽  
The Stability ◽  
Redox Index

As an alternative to the relatively complex and expensive spectroscopic methods, the redox properties of humic acids, determined by potentiometric titrations, have been used to evaluate the stability of soil organic C. The objective of the present study was to establish a Redox Index of C Stability (RICS) and to correlate it with some properties of the humic acids extracted from different modal soils in Brazil (distinct weathering stages or management) to facilitate system comparison. The RICS was efficient for soil comparison and variations were comparable to those of the chemical and spectroscopic methods used for humic acid characterization. The values of soil pH, point of zero salt effect, sum of bases, exchangeable Ca content, weathering index, as well as the humic acid O/C ratio, quinone and semiquinone free radical contents, aromatic C and fluorescence intensity were closely related with the RICS. The RICS was higher in less weathered soils, with more active clays and higher fertility. The RICS values of soils under long-term sugarcane management were ranked in decreasing order: unburned, burned with vinasse, burned without vinasse.

Photocatalytic oxidation and subsequent adsorption characteristics of humic acids

1996 ◽  
Vol 34 (9) ◽  
pp. 65-72 ◽  
Author(s):  
Miray Bekbölet ◽  
Ferhan Çeçen ◽  
Gülhan Özkösemen
Keyword(s):  
Activated Carbon ◽  
Humic Acid ◽  
Humic Acids ◽  
Photocatalytic Oxidation ◽  
Irradiation Time ◽  
Batch Reactor ◽  
Freundlich Isotherm ◽  
Oxidation Products ◽  
Adsorption Characteristics ◽  
Significant Change

Effect of TiO2 photocatalyzed oxidation on the degradation and decolorization of humic acids was studied. The photocatalytic oxidation products were further investigated in terms of adsorptivity on activated carbon. With photocatalytic oxidation in a lab-scale batch reactor significant decolorization and a decrease in UV280 and UV254 took place. Simultaneously there was a decrease in TOC and COD. Parallel to this an evolution of BOD5 was observed. Thus the BOD5/COD ratio increased with irradiation time and more biodegradable substances have been formed. A significant change in the structure of compounds in humic acid took place only after 3-4 hours of irradiation as determined by the decrease in COD/TOC ratio. Generally there was a slight decrease of adsorptivity after irradiation as concluded from the comparison of Freundlich isotherm constants for raw and irradiated humic acid. This decrease increased as the irradiation time increased. But for irradiation times to be used in practice in photocatalytic oxidation no significant change in adsorption is expected.

Anti-Herpes Simplex Virus Type 1 Activity of Humic Acid-Like Polymers and Their O-Diphenolic Starting Compounds

1997 ◽  
Vol 8 (3) ◽  
pp. 265-273 ◽  
Author(s):  
B Helbig ◽  
R Klöcking ◽  
P Wutzler
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Humic Acid ◽  
Herpes Simplex Virus Type ◽  
Functional Group ◽  
Group Analysis ◽  
Functional Group Analysis ◽  
Simplex Virus ◽  
Hsv 1

Phenolic polymers of the humic acid (HA) type, like other polyanionic substances, are inhibitors of herpes simplex virus type 1 (HSV-1) replication. The antiviral potency of the low molecular weight (MW) phenolic starting compounds has not been investigated systematically up to now. To reveal possible relationships between the chemical structure of o-diphenolic starting compounds and the anti-HSV-1 activity of HA-like polymers, nine polymers were synthesized by oxidation of the corresponding o-dihydroxybenzene derivatives. They were characterized by MW distribution, Fourier transform infra-red spectra and functional group analysis. Using an XTT-based tetrazolium reduction assay, both the low MW starting compounds and the synthesized polymers were examined for their antiviral and cytotoxic activities in HSV-1-infected Vera cells. The results demonstrate that most of the starting compounds failed to inhibit herpesvirus replication. The polymeric oxidation products (OP), however, developed detectable anti-HSV-1 activity with IC50 values in the range 2.3 [the OP of 3,4 dihydroxycinnamic acid (caffeic acid); KOP] to 42.1 μg mL−1 (3,4-dihydroxy-toluene OP). The CC50 of polymers varied between 40.8 (3,4-dihydroxybenzaldehyde OP) and >128 μg mL−1 (most polymers). Functional group analysis revealed that the presence of carboxylic groups in the starting compounds enhanced the antiviral activity and reduced the cytotoxicity of polymers. The introduction of a C=C double bond into the side chain [i.e. caffeic acid; 3-O-(3,4-dihydroxycinnamoyl)-d-chinic acid (chlorogenic acid; CH)] yielded the most effective polymers (KOP, CHOP). These may be considered as leader substances for HSV-1 inhibitors of the HA type.

Changes in the Humic Acid–Metal Complexation Characteristics Depending on Humification Degree / Humīnskābju – Metālu Kompleksveidošanās Rakstura Izmaiņas Atkarībā No Humifikācijas Pakāpes

2012 ◽  
Vol 51 (3) ◽  
pp. 228-237
Author(s):  
D. Dudare ◽  
M. Klavins
Keyword(s):  
Humic Acid ◽  
Stability Constants ◽  
Humic Acids ◽  
Complex Stability ◽  
Peat Layer ◽  
Raised Bog ◽  
Complexing Capacity ◽  
Humification Degree ◽  
Complexation Process ◽  
Complex Stability Constants

The aim of this study is to determine the Cu(II) complexing capacity and stability constants of Cu(II) complexes of humic acids isolated from two well-characterized raised bog peat profiles in respect to the basic properties and humification characteristics of the studied peats and their humic acids. The complex stability constants significantly change within the studied bog profiles and are well correlated with the age and decomposition degree of the peat layer from which the humic acids have been isolated. Among factors that influence this complexation process, molecular mass and ability to form micellar structures (supramolecules) of humic substances are of key importance.

EFFECT OF IRRIGATION AND GRASSING TO CHANGE SOME OF THE BIOLOGICAL PROPERTIES OF THE MINING OF BROWN CALCAREOUS SOILS

2019 ◽  
Vol 1 (1) ◽  
pp. 29-32
Author(s):  
Ruzimurod B. Boimurodov ◽  
Zebinisso Q. Bobokhonova
Keyword(s):  
Folic Acid ◽  
Humic Acid ◽  
Humic Acids ◽  
Rapid Growth ◽  
Growth And Development ◽  
Sharp Increase ◽  
Humus Content ◽  
Calcareous Soils ◽  
Biological Properties ◽  
Humus Accumulation

In this article is showing, that the irrigation mountain brown carbonate soils prone methods of irrigation and grassing comes the rapid growth and development of natural vegetation, which leads to intensive humus accumulation. Humus content in the upper layer is increased by 0.98% and a significantly smaller severely eroded. Increasing the amount of humus promotes accumulation mainly humic acids, that conducts to expansion of relations the content of humic acid: The content of folic acid. When grassing of soil traced sharp increase in the number associated with the related and R2 O3 humic acid.

Kinetic Adsorption of Humic Acids Mixture Obtained from Microalgae on Exfoliated Graphite Nanoplatelets

2018 ◽  
Vol 69 (1) ◽  
pp. 191-195
Author(s):  
Elena Radu ◽  
Elena Emilia Oprescu ◽  
Cristina Emanuela Enascuta ◽  
Catalina Calin ◽  
Rusandica Stoica ◽  
...  
Keyword(s):  
Humic Acid ◽  
Humic Acids ◽  
Alkali Treatment ◽  
Exfoliated Graphite ◽  
Acid Mixture ◽  
Acidic Ph ◽  
Graphite Nanoplatelets ◽  
Mixture Concentration ◽  
Ft Ir ◽  
Exfoliated Graphite Nanoplatelets

The dehydration of polysaccharides fraction in the presence of acid catalysts, is a chemical process in which results as secondary product humic matter. In our work, the humic acid mixture was for the first time based on our knowledge extracted from defatted microalgae biomass rich in polysaccharides by standard alkali treatment, followed by precipitation at acidic pH. The dried humic acid mixture has been characterized using infrared spectroscopic measurements (FT-IR). Exfoliated graphite nanoplatelets (xGnP) were used as new adsorbents for this type of humic acids mixture, their adsorption being investigated. The effect of several parameters such as: contact time, concentration of humic acid mixture, concentration of xGnP, temperature and pH of the solutions were studied. The process of adsorption took place with good results, in the following conditions: at a concentration of humic acid mixture of 18.6 mg L-1, an xGnP amount of 0.01 mg in 25 mL of solution, at a temperature of 25 �� and at acidic pH values, in aqueous solution.

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