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On the Acid−Base Properties of Humic Acid in Soil
Environmental Science & Technology, 2006Humic acid was isolated from three contrasting organic-rich soils and acid-base titrations performed over a range of ionic strengths. Results obtained were unlike most humic acid data sets; they showed a greater ionic strength dependency at low pH than at high pH.
Cooke, J. D. +2 more
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Adsorption mechanisms of nicotine on humic acid and clay humic acid complex
Zeitschrift für Pflanzenernährung und Bodenkunde, 1990AbstractThe adsorption isotherm of nicotine on humic acid ‐ surface was found to be multiphase according to the applied concentrations of nicotine. Each phase was characterized by its own change in free energy and represented a mechanism of interaction.
Ahmed H. Khairy +2 more
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Drugs of the future: humic acids
Processes of Petrochemistry and Oil RefiningHumic substances are natural and processable structures formed as a result of the decay of plants. They are yellow to black in colors, are entirely natural organic structures with hydrophilic properties and high molecular weight. Humic substances are ubiquitous organic compounds that arise during the chemical and microbiological oxidation process, the ...
Raşit Fikret Yılmaz, Ahmet Tutar
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Chemiluminescence of Humic Acids
Nature, 1967THE concept that humic acids (HA) are heteropolycondensates of phenolic substances is now widely accepted1,2. All the humic acids have hydroxyl, methoxy, or carbonyl groups connected with the aromatic parts of the nucleus. Our earlier investigations suggested that oxidation of hydroxyl groups attached to the aromatic ring may be accompanied by ...
DANUTA SŁAWIŃSKA, JANUSZ SŁAWIŃSKI
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Tetrahedron, 1967
Abstract Alkaline solutions of “humic acid” (HA) isolated from some eighty different soils and peats give ESR spectra indicative of the presence of remarkably stable semiquinone ion radicals. The type of spectrum is largely determined by the pH of the soil but not by the age of the soil or the nature of the plant cover, and the examination of the HA ...
N.M. Atherton +3 more
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Abstract Alkaline solutions of “humic acid” (HA) isolated from some eighty different soils and peats give ESR spectra indicative of the presence of remarkably stable semiquinone ion radicals. The type of spectrum is largely determined by the pH of the soil but not by the age of the soil or the nature of the plant cover, and the examination of the HA ...
N.M. Atherton +3 more
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Tetrahedron, 1968
Abstract The effect of KOH fusion, pyrolysis, and hydriodic acid on acid boiled humic acid (ABHA) has been studied. As many of the products of the KOH fusion of ABHA are obtained similarly from the “polymers” of o - or p -benzoquinone or furfural, it is probable that the fusion products shed little, if any, light on the constitution of HA.
M.V. Cheshire +2 more
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Abstract The effect of KOH fusion, pyrolysis, and hydriodic acid on acid boiled humic acid (ABHA) has been studied. As many of the products of the KOH fusion of ABHA are obtained similarly from the “polymers” of o - or p -benzoquinone or furfural, it is probable that the fusion products shed little, if any, light on the constitution of HA.
M.V. Cheshire +2 more
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Tetrahedron, 1971
Abstract The synthesis is described of quinones containing α-amino acid ester substituents and the structure of the products is established by NMR and mass spectroscopic techniques. Hydrolysis of the products with 6N HCl has been studied; the products behave as vinylogous amides but the release of nitrogen in the form of amino acid is low ...
P.A. Cranwell, R.D. Haworth
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Abstract The synthesis is described of quinones containing α-amino acid ester substituents and the structure of the products is established by NMR and mass spectroscopic techniques. Hydrolysis of the products with 6N HCl has been studied; the products behave as vinylogous amides but the release of nitrogen in the form of amino acid is low ...
P.A. Cranwell, R.D. Haworth
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Tetrahedron, 1967
Abstract The action of water and acids on “humic acid” (HA) is described, and it is concluded that HA is a complex of a polycyclic aromatic “core” responsible for the ESR spectrum which is attached to polysaccharides, proteins, relatively simple phenols and metals.
M.V. Cheshire +4 more
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Abstract The action of water and acids on “humic acid” (HA) is described, and it is concluded that HA is a complex of a polycyclic aromatic “core” responsible for the ESR spectrum which is attached to polysaccharides, proteins, relatively simple phenols and metals.
M.V. Cheshire +4 more
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2005
Humic acids are iodinated by elemental iodine and, if the iodine is present as iodide, by peroxidase-mediated reactions. It is demonstrated that iodination of humic acids leads to a product with a uniform distribution of iodine. It could not be unambiguously verified whether the enzymatically mediated iodination is a direct reaction between a ...
Jesper V. Christiansen, Lars Carlsen
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Humic acids are iodinated by elemental iodine and, if the iodine is present as iodide, by peroxidase-mediated reactions. It is demonstrated that iodination of humic acids leads to a product with a uniform distribution of iodine. It could not be unambiguously verified whether the enzymatically mediated iodination is a direct reaction between a ...
Jesper V. Christiansen, Lars Carlsen
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Humic Acid and Fulvic Acid Hinder Long-Term Weathering of Microplastics in Lake Water
Environmental Science & Technology, 2021Hanyu Wang, Hexinyue Huang, Yanqi Shi
exaly