Chemical Characteristics of Humic Compounds Isolated From Some Decomposed Marine Algae

The chemical and spectroscopic characteristics of humic compounds isolated from decomposed thalli of Fucus vesiculosus and Laminaria digitata, seaweed exudate, and dissolved organic matter in river water show that, in spite of several differences, their gross structural features are similar to those of humic compounds isolated from marine sediments or soils. Dominant functional groups are carboxyl and carbonyl but phenolic and alcoholic hydroxyl groups are also present in small proportions. Between 20 and 40% of humic acids are represented by fractions having molecular weight greater than 200,000, whereas the fulvic acids do not exceed 10,000. Carbon and nitrogen contents show a direct relation with molecular weight whereas the oxygen is inversely related.

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Biometrics in Laminaria digitata: A useful tool to assess biomass, carbon and nitrogen contents

Journal of Sea Research ◽

10.1016/j.seares.2008.06.006 ◽

2008 ◽

Vol 60 (3) ◽

pp. 215-219 ◽

Cited By ~ 25

Author(s):

F. Gevaert ◽

M.-A. Janquin ◽

D. Davoult

Keyword(s):

Biomass Carbon ◽

Laminaria Digitata ◽

Carbon And Nitrogen ◽

Nitrogen Contents

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Development of methods for the separation and characterization of natural organic matter in dam water

10.51415/10321/1182 ◽

2014 ◽

Author(s):

◽

Pinkie Sobantu

Keyword(s):

Molecular Weight ◽

Humic Acid ◽

Fulvic Acid ◽

Humic Substances ◽

Water Samples ◽

Fulvic Acids ◽

Hydroxyl Groups ◽

Humic And Fulvic Acids ◽

Vaal Dam

This project arose out the need for a simple method to analyse NOM on a routine basis. Water samples were obtained from the Vaal dam, which is one of the dams used by a hydroelectric power station. Analysis was preceded by separation of NOM into the humic and non-humic portions. The humic portion was separated into two fractions by employing a non-ionic resin (DAX-8) to separate humic acid from fulvic acid. High performance size exclusion chromatography (HPSEC), equipped with an Ultraviolet( UV) detector and an Evaporative Light Scattering (ELS) detector connected in series, was used to obtain molecular weight distribution information and the concentration levels of the two acids. Mixed standards of polyethylene oxide/glycol were employed to calibrate the selected column. Suwanee River humic acid standard was used as a certified reference material. The molecular weight distributions (MWDs) of the isolated fractions of humic and fulvic acids were determined with ELSD detection as weight-average (Mw), number-average (Mn) and polydispersity (ρ) of individual NOM fractions. The Mw/Mn ratio was found to be less than 1.5 in all the fractions, indicating that they have a low and narrow size fraction. An increase in Mn and Mw values, with increasing wavelength for all three humic substances (HS) examined was observed. The HS, isolated from the dam water, was found to be about the same molecular weight as the International Humic Acid Standard (IIHSS). For the fulvic acid standard, the molecular weight was estimated to be around 7500 Da. Characterization of NOM was done to assist in the identification of the species present in the water. FTIR-ATR was used to as a characterization tool to identify the functional groups in the structure of the humic and fulvic acid respectively present in the Vaal Dam. Analysis of the infrared (IR) spectra indicated that the humic acids of the Vaal dam have phenolic hydroxyl groups, hydroxyl groups, conjugated double bond of aromatic family (C=C), and free carboxyl groups. The isolation method has proved to be applicable and reliable for dam water samples and showed to successfully separate the humic substances from water and further separate the humic substances into its hydrophobic acids, namely, humic and fulvic acids. It can be concluded that the Eskom Vaal dam composes of humic substance which shows that the technique alone gives a very good indication of the characteristics of water. The HPSEC method used, equipped with UV and ELSD was able to identify the molecular weight range of NOM present in source water as it confirmed that the Eskom Vaal dam contains humic substances as humic acid and fulvic acid and these pose a health concern as they can form disinfectant byproducts in the course of water treatment with chemicals. FTIR characterization was successful as important functional groups were clearly assigned. Lastly, the use of the TOC and DOC values to calculate SUVA was also a good tool to indicate the organic content in water. It is recommended to use larger amounts of water must be processed to obtain useful quantities of the humic and fulvic acid fractions.

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Composition of low molecular weight impurities in dimethylmethylpheylsiloxane rubbers with terminal hydroxyl groups

Industrial laboratory Diagnostics of materials ◽

10.26896/1028-6861-2020-86-11-20-27 ◽

2020 ◽

Vol 86 (11) ◽

pp. 20-27

Author(s):

A. M. Filippov ◽

N. Yu. Semenkova ◽

S. M. Gorelov ◽

T. I. Shulyatieva ◽

P. A. Storozhenko

Keyword(s):

Molecular Weight ◽

Low Molecular Weight ◽

Hydroxyl Groups

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SULPHUR, CARBON, AND NITROGEN CONTENTS OF ORGANIC FRACTIONS FROM ACETYLACETONE EXTRACTS OF SOILS

Journal of Soil Science ◽

10.1111/j.1365-2389.1976.tb02003.x ◽

1976 ◽

Vol 27 (3) ◽

pp. 324-330 ◽

Cited By ~ 12

Author(s):

N. M. SCOTT ◽

G. ANDERSON

Keyword(s):

Carbon And Nitrogen ◽

Organic Fractions ◽

Nitrogen Contents

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Characterization of Soil Organic Matter Individual Fractions (Fulvic Acids, Humic Acids, and Humins) by Spectroscopic and Electrochemical Techniques in Agricultural Soils

Agronomy ◽

10.3390/agronomy11061067 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1067

Author(s):

Aleksandra Ukalska-Jaruga ◽

Romualda Bejger ◽

Guillaume Debaene ◽

Bożena Smreczak

Keyword(s):

Molecular Weight ◽

Organic Matter ◽

Soil Organic Matter ◽

Humic Substances ◽

Humic Acids ◽

Agricultural Soils ◽

Fulvic Acids ◽

Sorption Properties ◽

Aliphatic Chains

The objective of this paper was to investigate the molecular characterization of soil organic matter fractions (humic substances (HS): fulvic acids-FAs, humic acids-HAs, and humins-HNs), which are the most reactive soil components. A wide spectrum of spectroscopic (UV–VIS and VIS–nearIR), as well as electrochemical (zeta potential, particle size diameter, and polydispersity index), methods were applied to find the relevant differences in the behavior, formation, composition, and sorption properties of HS fractions derived from various soils. Soil material (n = 30) used for the study were sampled from the surface layer (0–30 cm) of agricultural soils. FAs and HAs were isolated by sequential extraction in alkaline and acidic solutions, according to the International Humic Substances Society method, while HNs was determined in the soil residue (after FAs and HAs extraction) by mineral fraction digestion using a 0.1M HCL/0.3M HF mixture and DMSO. Our study showed that significant differences in the molecular structures of FAs, Has, and HNs occurred. Optical analysis confirmed the lower molecular weight of FAs with high amount of lignin-like compounds and the higher weighted aliphatic–aromatic structure of HAs. The HNs were characterized by a very pronounced and strong condensed structure associated with the highest molecular weight. HAs and HNs molecules exhibited an abundance of acidic, phenolic, and amine functional groups at the aromatic ring and aliphatic chains, while FAs mainly showed the presence of methyl, methylene, ethenyl, and carboxyl reactive groups. HS was characterized by high polydispersity related with their structure. FAs were characterized by ellipsoidal shape as being associated to the long aliphatic chains, while HAs and HNs revealed a smaller particle diameter and a more spherical shape caused by the higher intermolecular forcing between the particles. The observed trends directly indicate that individual HS fractions differ in behavior, formation, composition, and sorption properties, which reflects their binding potential to other molecules depending on soil properties resulting from their type. The determined properties of individual HS fractions are presented as averaged characteristics over the examined soils with different physico-chemical properties.

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