Irreversible sorption of humic substances causes a decrease in wettability of clay surfaces as measured by a sessile drop contact angle method

Kholodov, V.A.; Milanovskiy, E.Y.; Konstantinov, A.I.; Tyugai, Z.N.; Yaroslavtseva, N.V.; Perminova, I.V.

Авторы: Kholodov V.A., Milanovskiy E.Y., Konstantinov A.I., Tyugai Z.N., Yaroslavtseva N.V., Perminova I.V.
Журнал: Journal of Soils and Sediments
Том: 18
Номер: 4
Год издания: 2018
Издательство: Ecomed Verlagsgesellschaft AG & Co.
Местоположение издательства: Germany
Первая страница: 1327
Последняя страница: 1334
DOI: 10.1007/s11368-016-1639-3
Аннотация: Purpose. To obtain quantitative assessments of the hydrophobic impact hydrophobizying impact of irreversible sorption of humic substances (HS) onto clay mineral surfaces using a sessile drop contact angle method. Materials and methods. To reach this goal,Clays combined with humics in ratios of 1:1 (kaolin ) and 2:1 (smectite) clays were used which were modified usingwith four humic materials :from different sources: ,1) sod podzolic; 2) soil; 3) , chernozem, peat, and 4) coal (leonardite). The humic materials were characterized using. elemental analysis, size exclusion chromatography, and 13C NMR spectroscopy. The bBoth clay samples were saturated with Ca2+ prior to modification with HS using a sorption isotherm technique. Contact angles (CA) of the obtained HS-clay complexes were determined using a static sessile drop method after drying the obtained HS-clay complexes in the form of a thin film. Results and discussion. HS modification rendered the both clays under study – kaolin and montomorillonite - more hydrophobic. In case of Ca-kaolin, the CA values increased from 27° (Ca-kaolin) up to 31-32° (all HS-kaolin complexes) with no significant difference between among the HS types used for modification. In the case of Ca-montmorillonite, the CA values increased from 41° (Ca-montmorillonite) up to 51° - 83° yielding with the following ascending trend for the humic types investigated: Chernozem HS < Coal HS < Peat HS < Sod-podzolic HS. This trend is in reverse to the degree of aromaticity of the HS, expressed as the content of aromatic carbon, and it is directly proportional to the molecular weight of each HS. Conclusions. Application of a sessile drop method showed increased surface hydrophobicity of HS HS-modified clays. Much more substantial hydrobobization was observed for montmorillonite as compared to kaolin, which was explained by the differences in the sorption mechanism. Keywords Contact angle • Humic substances • Hydrophobization • Kaolin • Montmorillonite • Sorption • Sessile drop method
Добавил в систему: Перминова Ирина Васильевна

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Irreversible sorption of humic substances causes a decrease in wettability of clay surfaces as measured by a sessile drop contact angle methodстатья Исследовательская статья

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