Composition of fulvic acids after the mechanical activation of peats

Ivanov, Anton A.; Мальцева, Е. В.; Yudina, N. V.

doi:10.3103/s0361521916010055

Cited by 6 publications

(4 citation statements)

References 1 publication

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“…These results were then analyzed using Langmuir and Freundlich sorption It was expected that the mechanochemical oxidation of peat using Na 2 CO 3 •1.5H 2 O 2 would proceed similarly to the examples described for brown coal. It has long been known that on the surface of brown coal many radicals are formed as a result of mechanical activation [65,66]. In [38] it was shown that the mechanochemical oxidation of brown coal by Na 2 CO 3 •1.5H 2 O 2 occurs with the participation of a free radical mechanism and produces new oxygen-containing groups.…”

Section: Adsorption Isothermmentioning

confidence: 99%

Modification of Natural Peat for Removal of Copper Ions from Aqueous Solutions

Shvartseva

Skripkina

Gaskova

et al. 2022

Water

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This study aimed at estimating peat adsorption properties for copper ion removal from aqueous solutions during peat modification. Two peat modifications have been studied using batch tests and quantitatively reproduced with instrumental analysis by using spectrometric, potentiometric, and thermodynamic modeling methods. The first variation—mechanical activation—was carried out in a planetary mill; for the second one—mechanochemical activation—dry sodium percarbonate (Na2CO3∙1.5H2O2) was added. The adsorption of copper ions was studied in the concentration range from 10–150 mg/L with an interaction time from 0.25–12 h. Both modifications led to significant changes in the interaction energy in the adsorption layer; thus, the acceptor properties of macromolecules were enhanced from natural peat to mechanically activated peat and mechanochemically activated peat. FTIR spectra, specific surface area characteristics, and sorption experiments show the predominantly chemical nature of copper sorption. Maximum adsorption capacity was determined to be 24.1, 42.1, and 16.0 mg/g for natural peat, mechanically activated peat, and mechanochemically activated peat, respectively. The example of peat mechanochemically oxidized with Na2CO3∙1.5H2O2 shows that the improvement in the physicochemical properties (CBET and specific surface area) plays a smaller role in the sorption capacity in relation to copper ions than the presence of phenolic and carboxyl groups, the content of which decreases during oxidation.

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Section: Adsorption Isothermmentioning

confidence: 99%

Modification of Natural Peat for Removal of Copper Ions from Aqueous Solutions

Shvartseva

Skripkina

Gaskova

et al. 2022

Water

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“…In general, humic fractions containing more functional groups with higher dissociation ability can be easily dissolved. In contrast, humic fractions low in acidic functional groups can be difficult to dissolve [4,10,24,25,31,31,32,34,35]. The dissociation ability of acidic functional groups of humic acids is closely associated with their solubility.…”

Section: Discussionmentioning

confidence: 99%

“…They are characterized by a lower degree of aromaticity, as compared with that of humic acids, and a considerable predominance of aliphatic substituents. The qualitative composition of functional groups is the same as that in humic molecules [35]. Similarly, the fraction of humic acids which is dissolved in water, or rather in the aqueous phase in humic-containing systems is the most active fraction of humic acids.…”

Section: Introductionmentioning

confidence: 97%

“…The application of the method on samples of IHSS, regarded as standards and reference materials of humic substances, is subsequent logical step in this field of humic research. Fulvic acids are the most mobile and reactive components of humic substances, and are completely soluble in water and aqueous solutions [2][3][4][5][6]35]. They are characterized by a lower degree of aromaticity, as compared with that of humic acids, and a considerable predominance of aliphatic substituents.…”

Section: Introductionmentioning

confidence: 99%

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New possibility for characterization of dissociation behaviour of supramolecular electrolytes: results obtained for the International Humic Substances Society standard and reference samples by coulometry

Klučáková

2021

Chem. Biol. Technol. Agric.

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Background Humic substances can be considered as polyelectrolytes with supramolecular character and complicated behaviour in water environment. The fractions of humic substances dissolved in water are the most active ones and determinative for their functioning in nature, where the proton-binding and dissociation ability play a crucial role. The dissociation behaviour of humic and fulvic acids can be affected by different circumstances including their concentration which is directly connected with the molecular organization of humic particles in solution and the accessibility of their ionizable functional groups. This study is focused just on these active fractions and their dissociation behaviour in the dependence on their content in studied system. Results Standards and reference samples of International Humic Substances Society were used. Flow-through coulometry was used to determine the total content of acidic functional groups in fulvic solutions and humic leachates. The amount of dissociated acidic groups was determined on the basis of potentiometry. Several differences between the behaviour of humic and fulvic acids were found. While whole samples of fulvic acids including the weakest functional groups were analysed, only the active dissolved humic fractions containing stronger acidic functional groups were characterized. The fractions containing higher amounts of the weakest functional groups remained insoluble. The dissociation degree of fulvic acids decreased with their increasing content, but a maximum on its concentration dependence obtained for humic acids was observed. Conclusions Two different values of dissociation constants were determined for each sample. The first was determined on the basis of the extrapolation of infinite dilution, second was determined as their average value in the region of high concentrations in which it was constant. Obtained values characterize the functioning of dissolved humic substances from point of view of their dissociation ability. The results obtained by this approach can help to predict the acid–base behaviour of dissolved organic carbon in soil and generally in nature. The acid–base behaviour of dissolved organic carbon depends on its ratio to water. It behaves differently in soil which is dry and in soil which is wet or saturated by water.

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Activation of fulvic acid-like in paper mill effluents using H2O2/TiO2 catalytic oxidation: Characterization and salt stress bioassays

Yao

Wang

et al. 2019

Journal of Hazardous Materials

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Composition of fulvic acids after the mechanical activation of peats

Cited by 6 publications

References 1 publication

Modification of Natural Peat for Removal of Copper Ions from Aqueous Solutions

Modification of Natural Peat for Removal of Copper Ions from Aqueous Solutions

New possibility for characterization of dissociation behaviour of supramolecular electrolytes: results obtained for the International Humic Substances Society standard and reference samples by coulometry

Activation of fulvic acid-like in paper mill effluents using H2O2/TiO2 catalytic oxidation: Characterization and salt stress bioassays

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