Influence of pH on the surface activity of humic acid: micelle-like aggregate formation and interfacial adsorption

Terashima, Masanao; Fukushima, Masami; Tanaka, Shunitz

doi:10.1016/j.colsurfa.2004.08.028

Cited by 134 publications

(81 citation statements)

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“…The average pK a of the carboxylic groups of the HA is 4.5 [55,56]. More recent studies [57], based on the Anderson-Hasselbach interpretation, have established that the apparent pK a of a peat humic acid was 4.93. Alvarez-Puebla and Garrido [58] measured the zeta potential of a grey humic acid against pH and observed a drop in the pH intervals 3.6 to 4.2 and 5.9 to 6.2, with a section of null slope between the two.…”

Section: Discussionmentioning

confidence: 99%

Chemical and spectroscopic characterization of insoluble and soluble humic acid fractions at different pH values

Baglieri

Vindrola

Gennari

et al. 2014

Chem. Biol. Technol. Agric.

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Background: Humic acids (HA) are organic molecules with complex structure and function and variable properties. They are insoluble in strongly acid pH conditions. At present, it is not clear how much is the amount of HA in solution at the pH of natural soils nor are known the characteristics of the different soluble fractions and their possible association with the inorganic phase of soil. The scope of this work was to characterize the soluble and insoluble fractions obtained by acidifying Na humate solution at pH values 3, 5, and 7 and to compare these fractions with the HA obtained at pH 1. At each pH, the precipitate and the soluble fractions were separated and characterized by elemental analysis, total acidity and carboxylic group content, infrared, and 13 C NMR and

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Section: Discussionmentioning

confidence: 99%

Chemical and spectroscopic characterization of insoluble and soluble humic acid fractions at different pH values

Baglieri

Vindrola

Gennari

et al. 2014

Chem. Biol. Technol. Agric.

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“…Numerous studies have shown that the extent and type of HA aggregation depends on HA components, pH, ionic strength, type of electrolyte, and temperature (Palmer and von Wandruszka 2001;Terashima et al 2004;Chilom et al 2009;Wang et al 2013). The obtained values of the CQ internal oxidation acc.…”

Section: Resultsmentioning

confidence: 99%

Studying of the interaction between peat humic acids and metazachlor using spectroscopy methods

et al. 2018

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Purpose The analysis covered the interaction of humic acids (HA) isolated from peats with the metazachlor using spectroscopic methods. Materials and methods Five peatlands have been selected for the study in the southern and northern parts of Poland. Extraction of humic acids (HA1, HA2, HA3, HA4, and HA5) was performed using a procedure recommended by the International Humic Substances Society. Metazachlor 500 SC with metazachlor as a biologically active substance [2-chloro-N-(pyrazol-1-ylmethyl)acet-2′,6′-xylidide] has been used. HA have been assessed on the basis of their elemental composition. Spectroscopic techniques have been used to study the HA structure and their interaction with metazachlor including: UVvisible spectroscopy, dynamic light scattering, and delayed luminescence (DL) Results and discussion Based on their morphological and chemical properties, the studied peat soils can be classified as follows: (1) Eutric Murshic Sapric Histosols, (2) Eutric Sapric Histosols, (3) Eutric Hemic Histosols, (4) Eutric Fibric Histosols, and (5) Dystric Dranic Hemic Histosols according to the WRB guidelines (2015). Results showed that the largest particle size, measured by E 4/6 coefficient, was found in HA2 sample, while the smallest in HA3 sample. The addition of metazachlor to HA solutions reduced the values of E 4/6 coefficient by 33 to 72%, while the values of hydrodynamic diameter by 4 to 32%. No significant changes were found between E 4/6 after adding of metazachlor to HA solutions. The largest changes in DL intensity, excited both by blue and red light after herbicide addition, were observed in HA2 sample, which is characterized by the largest particle size, the highest oxygen content and CQ value as well as the lowest Baromatization rate^value. Conclusions The particle sizes of HA molecules measured by E 4/6 coefficient do not impact on the particle sizes of HA-herbicide systems measured by the same ratio. The delayed luminescence may become valuable, because it is simple, fast, and sensitive. Additionally, the results show minor errors comparing with chemical methods. This method may provide information about structure and nature of humic acids, as well as their photoreactivity. The using of delayed luminescence in studies of HApesticides interaction may enable us to better understand the luminescence properties of HA.

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“…where R is the gas constant, T is absolute temperature, g is the surface tension of the HA solution, and C is the concentration of humic substances (Terashima et al, 2004).…”

Section: Surface Tension Measurementsmentioning

confidence: 99%

Surface Activity of Humic Acids Depending on Their Origin and Humification Degree

Kļaviņš

Purmalis

2014

Proceedings of the Latvian Academy of Sciences. Section B. Natural, Exact, and Applied Sciences.

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Contributed by Mâris KïaviòðHumic substances are able to reduce the surface tension of their solutions and thus can act as surface-active substances in the natural environment, which may have industrial application. The ability to influence the surface tension of humic acid solutions depends on the origin of the humic acids. The objective of this study was comparison of the ability of humic acids of different origin (soil, water, peat, lignite etc.)

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Influence of pH on the surface activity of humic acid: micelle-like aggregate formation and interfacial adsorption

Cited by 134 publications

References 29 publications

Chemical and spectroscopic characterization of insoluble and soluble humic acid fractions at different pH values

Chemical and spectroscopic characterization of insoluble and soluble humic acid fractions at different pH values

Studying of the interaction between peat humic acids and metazachlor using spectroscopy methods

Surface Activity of Humic Acids Depending on Their Origin and Humification Degree

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