Details
| Original language | English |
|---|---|
| Pages (from-to) | 563-574 |
| Number of pages | 12 |
| Journal | Journal of Colloid and Interface Science |
| Volume | 667 |
| Early online date | 16 Apr 2024 |
| Publication status | Published - Aug 2024 |
Abstract
Hypothesis: Freeze-thaw cycles (FTC) in soils can cause the aggregation of dissolved organic matter but controlling factors are little understood. Experiments: In freeze–thaw experiments with tannic acid (TA) as model substance, we studied the effect of TA concentration, pH, electrolytes (NaCl, CaCl2, AlCl3), and number of FTC on particle formation. Tannic acid (0.005 to 10 g L−1) was exposed to 1–20 FTC at pH 3 and 6. The size and shape of particles was determined by confocal laser scanning microscopy. Particle stability was deduced from the equivalent circle diameter (ECD) obtained in dry state and the hydrodynamic diameter measured in thawing solutions. Findings: Tannic acid particles occurred as plates and veins, resembling the morphology of ice grain boundaries. Low pH and presence of electrolytes favored the formation of large particles. The freeze-concentration effect was most intense at low TA concentrations and increased with the number of FTC. While ECD of particles formed at low TA concentrations were smaller than at high concentrations, it was vice versa in the thawed state. At low TA concentrations, higher crystallization pressure of ice caused enhanced stability of large particles. We conclude that FTC can strongly alter the physical state of dissolved organic matter, with likely consequences for its bioavailability.
Keywords
- Equivalent circle diameter, Freeze-concentration, Hydrodynamic diameter, Ice exclusion, Particle shape, Particle stability, Self-aggregation
ASJC Scopus subject areas
- Materials Science(all)
- Electronic, Optical and Magnetic Materials
- Materials Science(all)
- Biomaterials
- Materials Science(all)
- Surfaces, Coatings and Films
- Chemical Engineering(all)
- Colloid and Surface Chemistry
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In: Journal of Colloid and Interface Science, Vol. 667, 08.2024, p. 563-574.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Size, shape, and stability of organic particles formed during freeze–thaw cycles
T2 - Model experiments with tannic acid
AU - Dultz, Stefan
AU - Speth, Myriam
AU - Kaiser, Klaus
AU - Mikutta, Robert
AU - Guggenberger, Georg
N1 - Funding Information: This study was carried out within the framework of the Deutsche Forschungsgemeinschaft funded research unit RU 2179 \u201CMAD Soil \u2013 Microaggregates: Formation and turnover of the structural building blocks of soils\u201D (DFG RU 2179) under the project 251268514.
PY - 2024/8
Y1 - 2024/8
N2 - Hypothesis: Freeze-thaw cycles (FTC) in soils can cause the aggregation of dissolved organic matter but controlling factors are little understood. Experiments: In freeze–thaw experiments with tannic acid (TA) as model substance, we studied the effect of TA concentration, pH, electrolytes (NaCl, CaCl2, AlCl3), and number of FTC on particle formation. Tannic acid (0.005 to 10 g L−1) was exposed to 1–20 FTC at pH 3 and 6. The size and shape of particles was determined by confocal laser scanning microscopy. Particle stability was deduced from the equivalent circle diameter (ECD) obtained in dry state and the hydrodynamic diameter measured in thawing solutions. Findings: Tannic acid particles occurred as plates and veins, resembling the morphology of ice grain boundaries. Low pH and presence of electrolytes favored the formation of large particles. The freeze-concentration effect was most intense at low TA concentrations and increased with the number of FTC. While ECD of particles formed at low TA concentrations were smaller than at high concentrations, it was vice versa in the thawed state. At low TA concentrations, higher crystallization pressure of ice caused enhanced stability of large particles. We conclude that FTC can strongly alter the physical state of dissolved organic matter, with likely consequences for its bioavailability.
AB - Hypothesis: Freeze-thaw cycles (FTC) in soils can cause the aggregation of dissolved organic matter but controlling factors are little understood. Experiments: In freeze–thaw experiments with tannic acid (TA) as model substance, we studied the effect of TA concentration, pH, electrolytes (NaCl, CaCl2, AlCl3), and number of FTC on particle formation. Tannic acid (0.005 to 10 g L−1) was exposed to 1–20 FTC at pH 3 and 6. The size and shape of particles was determined by confocal laser scanning microscopy. Particle stability was deduced from the equivalent circle diameter (ECD) obtained in dry state and the hydrodynamic diameter measured in thawing solutions. Findings: Tannic acid particles occurred as plates and veins, resembling the morphology of ice grain boundaries. Low pH and presence of electrolytes favored the formation of large particles. The freeze-concentration effect was most intense at low TA concentrations and increased with the number of FTC. While ECD of particles formed at low TA concentrations were smaller than at high concentrations, it was vice versa in the thawed state. At low TA concentrations, higher crystallization pressure of ice caused enhanced stability of large particles. We conclude that FTC can strongly alter the physical state of dissolved organic matter, with likely consequences for its bioavailability.
KW - Equivalent circle diameter
KW - Freeze-concentration
KW - Hydrodynamic diameter
KW - Ice exclusion
KW - Particle shape
KW - Particle stability
KW - Self-aggregation
UR - http://www.scopus.com/inward/record.url?scp=85190966300&partnerID=8YFLogxK
U2 - 10.1016/j.jcis.2024.04.080
DO - 10.1016/j.jcis.2024.04.080
M3 - Article
C2 - 38657540
AN - SCOPUS:85190966300
VL - 667
SP - 563
EP - 574
JO - Journal of Colloid and Interface Science
JF - Journal of Colloid and Interface Science
SN - 0021-9797
ER -