Determination of the protonation enthalpy of humic acid by calorimetric titration technique

Kimuro, Shingo; Kirishima, Akira; Sato, Nobuaki

doi:10.1016/j.jct.2014.10.010

Cited by 18 publications

(3 citation statements)

References 19 publications

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“…Firstly, manure is rich in alkaline substances which can directly neutralize acidogenic ions and effectively replenish exchangeable base cations in the soil [29]. Secondly, a large amount of acidic oxygen-containing functional groups contained in manure could increase the negative charge sites of the soil through carboxyl protonation and enhance soil pHBC, thereby enhancing soil resistance to acidification [6,30,31]. Moreover, manure is effective in adsorbing reactive hydrogen and aluminum, thus reducing total acidity, especially from exchangeable aluminum [16].…”

Section: Regulation Of Pig Manure On the Acidity Of Red Soilmentioning

confidence: 99%

Long-Term Application of Pig Manure to Ameliorate Soil Acidity in Red Upland

Luo,

Long,

Sun

et al. 2023

Agriculture

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While the application of manure to improve soil quality has attracted attention, the effect of pig manure application rates on soil acidity remains poorly understood. In this study, we analyzed the changes and correlations between soil acidity, pH buffer capacity (pHBC), soil chemical properties, and crop yields after 8 years of pig manure application at different rates (i.e., 0, 7.5, 15, 30, and 45 Mg ha−1) in a red upland soil (Ultisol). With an increase in the application rates, the crop yields were 0.77–8.85 times higher; the pH was enhanced by 0.4–0.8 units; and the soil organic matter (SOM), pHBC, iron activation (Feo), exchangeable calcium (ExCa), and exchangeable magnesium (ExMg) contents increased by up to 74.1%, 92.7%, 36.7%, 62.2%, and 48.7%, respectively, whereas that of total exchangeable acid (ExAcid) decreased by 17.2–52.9%. The crop yields were positively related to the soil pH but negatively correlated with ExAcid. Redundancy analysis revealed ExAcid and pHBC were more sensitive than pH was to the other chemical indicators. ExAcid was negatively correlated with SOM and ExCa; pHBC was positively correlated with ExMg, TN, SOM, and Feo. In conclusion, the crop yield could be improved by adjusting the soil acidity characteristics, and the application of pig manure reduced the soil acidity, with an optimal application rate of 15 Mg·ha−1.

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Section: Regulation Of Pig Manure On the Acidity Of Red Soilmentioning

confidence: 99%

Long-Term Application of Pig Manure to Ameliorate Soil Acidity in Red Upland

Luo,

Long,

Sun

et al. 2023

Agriculture

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“…The effects of metal ions on K d values can probably be explained by considering the structure of the electrical double layer around the samples [22][23][24]. Since cationic metal ions are fixed to sample matrix, they potentially give high charge density due to ion exchange processes.…”

Section: Kd (Ml/g) MI Concentration In Solution (M)mentioning

confidence: 99%

Interaction of 137Cs with Sumedang Clay as Natural Barrier of Radwaste Disposal

2019

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The interaction of 137 Cs with Sumedang clay as a natural barrier for radwaste disposal system has been studied. The initial concentration of Cs was 10 -8 M for the experiments on the contact time and the effect of Na and K concentrations on the sorption of 137 Cs; however, the initial concentration ranging from 10 -8 to 10 -3 M of CsCl in the solution for the effect of CsCl concentration. The distribution coefficient K d is used as the indicator of 137 Cs sorption into samples. It was found that the K d values decreased nonlinearly with the concentration of Na and K, and also to the effects of CsCl concentration. A Freundlich isotherm was proposed to explain the sorption phenomena observed in the experiment. Conclusion of the experiments shown that the presence of metal ions such as Na + and K + and variation of CsCl concentrations in the solution have a significant effect on the sorption of 137 Cs to the samples. The results should be taken into account for the assessment or selection of the site of radwaste disposal facility in the future.

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“…Humic substances are heterogeneous mixtures of organic materials formed by the humification of animals, plants and microbes [1,2]. They are the most widespread natural complexing agents occurring in soils, sediments and water.…”

Section: Introductionmentioning

confidence: 99%

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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Determination of the protonation enthalpy of humic acid by calorimetric titration technique

Cited by 18 publications

References 19 publications

Long-Term Application of Pig Manure to Ameliorate Soil Acidity in Red Upland

Long-Term Application of Pig Manure to Ameliorate Soil Acidity in Red Upland

Interaction of 137Cs with Sumedang Clay as Natural Barrier of Radwaste Disposal

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

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