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Separations
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Research Progress on Extraction and Characterization of Humus
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Research Progress on Extraction and Characterization of Humus

A special issue of Separations (ISSN 2297-8739). This special issue belongs to the section "Analysis of Natural Products and Pharmaceuticals".

Deadline for manuscript submissions: closed (31 May 2022) | Viewed by 6243

Special Issue Editor

Dr. Denis Pankratov

E-Mail Website1 Website2 Website3
Guest Editor
Division of Radiochemistry, Department of Chemistry, Lomonosov Moscow State University, 119991 Moscow, Russian Federation
Interests: humic substances; inorganic chemistry; Mössbauer spectroscopy; solid-state and materials chemistry

Special Issue Information

Dear Colleagues,

Humus is a stable natural product of the joint evolution of living and nonliving matter. It is formed as a result of repeated transformation of plant and animal remains in the presence of minerals under the influence of biological, climatic, and geological factors for a long time. Humus is not just a specific product of biological waste disposal, but also an important soil component. In particular, it acts as a stabilizer of the physical and chemical state of soils. Moreover, it acts as a source and regulator of the supply of nutrients to plants and soil organisms while also serving as their habitat.

Humus, being a complex composite material, contains both organic (mainly) and inorganic substances. From the point of view of chemistry, humus is a dissipative supramolecular system of polymolecular assemblies characterized by nonstoichiometric elemental composition, polydisperse distribution of molecular weights, irregular structure, and heterogeneity of structural units.

Studying such a complex object is a daunting task for researchers of a wide variety of specializations. This is a challenge from nature itself for humankind, which already knows a lot about the structure of distant galaxies and "close" viruses but has not made much progress in studying what is literally under its feet and what has been "feeding" it for millions of years. All the more interesting is the theme of our Special Issue: "Research Progress on Extraction and Characterization of Humus". In this issue, we would like to consider the latest data on new methods of isolation and separation of humus components, as well as the use of modern research technologies for the characterization of humus; its fractions, including humin and humic substances (humic and fulvic acids); and related materials (e.g., lignohumates, biochar).

Dr. Denis Pankratov
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Separations is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Humus
  • Humin
  • Humic substance
  • Humic acids
  • Fulvic acids
  • Biochar
  • Lignohumates
  • Soil organic matter
  • Natural organic matter
  • Extraction techniques
  • Separation techniques

Published Papers (2 papers)

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Research

13 pages, 1926 KiB  
Article
Formation of Humic-Like Substances during the Technological Process of Lignohumate® Synthesis as a Function of Time
by Olga Yakimenko, Andrey Stepanov, Svetlana Patsaeva, Daria Khundzhua, Olesya Osipova and Oleg Gladkov
Separations 2021, 8(7), 96; https://0-doi-org.brum.beds.ac.uk/10.3390/separations8070096 - 03 Jul 2021
Cited by 10 | Viewed by 2593
Abstract
The composition, structure, and biological activity of humic-like substances (HLS) synthesized in the process of lignosulfonate conversion for the production of the humic product Lignohumate® (LH) were examined. It is shown that during the hydrolytic-oxidative process, the transformation of raw material and [...] Read more.
The composition, structure, and biological activity of humic-like substances (HLS) synthesized in the process of lignosulfonate conversion for the production of the humic product Lignohumate® (LH) were examined. It is shown that during the hydrolytic-oxidative process, the transformation of raw material and accumulation of HLS occur. Data on the chemical (elemental content, functional groups, FTIR) and spectral (absorbance and fluorescence) parameters and biological activity (in phytotest) combined with PCA show that the LH samples can be divided into three groups, depending on the duration of synthesis: initial raw material (0-time sample); “young” HLS (15–30 min), and “mature” HLS in 45–120 min of treatment. During the first 30 min, reactions similar to the ones that occur during lignin humification in nature take place: depolymerization, oxidative carboxylation, and further polycondensation with the formation and accumulation of HLS. After 45–60 min, the share of HLS reaches a maximum, and its composition stabilizes. Biological activity reaches a maximum after 45–60 min of treatment, and at that stage, the further synthesis process can be stopped. Further processing (up to 2 h and more) does not provide any added value to the humic product. Full article
(This article belongs to the Special Issue Research Progress on Extraction and Characterization of Humus)
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18 pages, 3139 KiB  
Article
Assessments of Organic Carbon Stabilization Using the Spectroscopic Characteristics of Humic Acids Separated from Soils of the Lena River Delta
by Vyacheslav Polyakov and Evgeny Abakumov
Separations 2021, 8(6), 87; https://0-doi-org.brum.beds.ac.uk/10.3390/separations8060087 - 20 Jun 2021
Cited by 9 | Viewed by 2634
Abstract
In the Arctic zone, where up to 1024 × 1013 kg of organic matter is stored in permafrost-affected soils, soil organic matter consists of about 50% humic substances. Based on the analysis of the molecular composition of humic acids, we assessed the processes [...] Read more.
In the Arctic zone, where up to 1024 × 1013 kg of organic matter is stored in permafrost-affected soils, soil organic matter consists of about 50% humic substances. Based on the analysis of the molecular composition of humic acids, we assessed the processes of accumulation of the key structural fragments, their transformations and the stabilization rates of carbon pools in soils in general. The landscape of the Lena River delta is the largest storage of stabilized organic matter in the Arctic. There is active accumulation and deposition of a significant amount of soil organic carbon from terrestrial ecosystems in a permafrost state. Under ongoing climate change, carbon emission fluxes into the atmosphere are estimated to be higher than the sequestration and storing of carbon compounds. Thus, investigation of soil organic matter stabilization mechanisms and rates is quite an urgent topic regarding polar soils. For study of molecular elemental composition, humic acids were separated from the soils of the Lena River delta. Key structural fragments of humic matter were identified and quantified by CP/MAS 13C NMR spectroscopy: carboxyl (–COOR); carbonyl (–C=O); CH3–; CH2–; CH-aliphatic; –C-OR alcohols, esters and carbohydrates; and the phenolic (Ar-OH), quinone (Ar = O) and aromatic (Ar–) groups as benchmark Cryosols of the Lena delta river terrestrial ecosystem. Under the conditions of thermodynamic evolutionary selection, during the change between the dry and wet seasons, up to 41% of aromatic and carboxyl fragments accumulated in humic acids. Data obtained showed that three main groups of carbon played the most important role in soil organic matter stabilization, namely C, H-alkyls ((CH2)n/CH/C and CH3), aromatic compounds (C-C/C-H, C-O) and an OCH group (OCH/OCq). The variations of these carbon species’ content in separated humics, with special reference to soil–permafrost organic profiles’ recalcitrance in the current environment, is discussed. Full article
(This article belongs to the Special Issue Research Progress on Extraction and Characterization of Humus)
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