Details
| Originalsprache | Englisch |
|---|---|
| Seiten (von - bis) | 10-19 |
| Seitenumfang | 10 |
| Fachzeitschrift | Journal of hydrology |
| Jahrgang | 382 |
| Ausgabenummer | 1-4 |
| Publikationsstatus | Veröffentlicht - 1 März 2010 |
Abstract
An accurate method to determine contact angles (CA) of soils as a measure of water repellency is still missing. In the present research, we evaluated and compared different methods to determine the CA of dry soil samples. Experiments were made by using a set of porous materials (silt, sand and glass beads) with different levels of water repellency. The CAs were measured with the Capillary Rise Method (θCRM; liquid penetration into a 3-d system), the Wilhelmy plate method (θWPM; measurement of capillary forces acting on a plane sample) and the Sessile Drop Method (θSDM; optical CA analysis of drop contour on a plane sample). Results were compared with the CAs calculated from capillary rise in long vertical columns (θECR), where liquid profiles of the final capillary rise of water and ethanol, respectively, were used to derive the contact angle under the assumed equilibrium conditions. The results showed the overestimation of the CA by using the well established bi-liquid CRM technique for porous materials, in particular for material with a low degree of water repellency (CA < 40°) and for the finer textured materials. In contrast, a variant of the Wilhelmy plate method, i.e. the cosine-averaged advancing CA and receding CA (θEWPM), as well as the Sessile Drop CA, θSDM, were close to the ones of θECR. We concluded that θEWPM and θSDM are apparent CA, but nevertheless able to predict the impact of wettability on the final capillary rise which is affected by pore topology as well as by wettability.
ASJC Scopus Sachgebiete
- Umweltwissenschaften (insg.)
- Gewässerkunde und -technologie
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in: Journal of hydrology, Jahrgang 382, Nr. 1-4, 01.03.2010, S. 10-19.
Publikation: Beitrag in Fachzeitschrift › Artikel › Forschung › Peer-Review
}
TY - JOUR
T1 - Direct determination of contact angles of model soils in comparison with wettability characterization by capillary rise
AU - Ramírez-Flores, Juan Carlos
AU - Bachmann, Jörg
AU - Marmur, Abraham
N1 - Funding information: This paper is part of the project “Surface Energy Characterization of Heterogeneous Porous Media: Theoretical and Experimental Assessment of the Wettability of the Soil”, funded by the Niedersachsen Foundation (NHDF N22002).
PY - 2010/3/1
Y1 - 2010/3/1
N2 - An accurate method to determine contact angles (CA) of soils as a measure of water repellency is still missing. In the present research, we evaluated and compared different methods to determine the CA of dry soil samples. Experiments were made by using a set of porous materials (silt, sand and glass beads) with different levels of water repellency. The CAs were measured with the Capillary Rise Method (θCRM; liquid penetration into a 3-d system), the Wilhelmy plate method (θWPM; measurement of capillary forces acting on a plane sample) and the Sessile Drop Method (θSDM; optical CA analysis of drop contour on a plane sample). Results were compared with the CAs calculated from capillary rise in long vertical columns (θECR), where liquid profiles of the final capillary rise of water and ethanol, respectively, were used to derive the contact angle under the assumed equilibrium conditions. The results showed the overestimation of the CA by using the well established bi-liquid CRM technique for porous materials, in particular for material with a low degree of water repellency (CA < 40°) and for the finer textured materials. In contrast, a variant of the Wilhelmy plate method, i.e. the cosine-averaged advancing CA and receding CA (θEWPM), as well as the Sessile Drop CA, θSDM, were close to the ones of θECR. We concluded that θEWPM and θSDM are apparent CA, but nevertheless able to predict the impact of wettability on the final capillary rise which is affected by pore topology as well as by wettability.
AB - An accurate method to determine contact angles (CA) of soils as a measure of water repellency is still missing. In the present research, we evaluated and compared different methods to determine the CA of dry soil samples. Experiments were made by using a set of porous materials (silt, sand and glass beads) with different levels of water repellency. The CAs were measured with the Capillary Rise Method (θCRM; liquid penetration into a 3-d system), the Wilhelmy plate method (θWPM; measurement of capillary forces acting on a plane sample) and the Sessile Drop Method (θSDM; optical CA analysis of drop contour on a plane sample). Results were compared with the CAs calculated from capillary rise in long vertical columns (θECR), where liquid profiles of the final capillary rise of water and ethanol, respectively, were used to derive the contact angle under the assumed equilibrium conditions. The results showed the overestimation of the CA by using the well established bi-liquid CRM technique for porous materials, in particular for material with a low degree of water repellency (CA < 40°) and for the finer textured materials. In contrast, a variant of the Wilhelmy plate method, i.e. the cosine-averaged advancing CA and receding CA (θEWPM), as well as the Sessile Drop CA, θSDM, were close to the ones of θECR. We concluded that θEWPM and θSDM are apparent CA, but nevertheless able to predict the impact of wettability on the final capillary rise which is affected by pore topology as well as by wettability.
KW - Capillary rise
KW - Contact angle
KW - Mixed water repellency
UR - http://www.scopus.com/inward/record.url?scp=75349111672&partnerID=8YFLogxK
U2 - 10.1016/j.jhydrol.2009.12.014
DO - 10.1016/j.jhydrol.2009.12.014
M3 - Article
AN - SCOPUS:75349111672
VL - 382
SP - 10
EP - 19
JO - Journal of hydrology
JF - Journal of hydrology
SN - 0022-1694
IS - 1-4
ER -