Effect of Temperature on Surfactant-Driven Water Movement in Wet “Unsaturated” Sand

Abstract

The effect of temperature on the surfactant-driven movement of water in wet “unsaturated” sand was investigated and correlated with the equilibrium spreading pressure of the surfactant and the character of the surfactant monolayer at πe. The previously determined criteria for surfactant effectiveness were confirmed. An approximately linear relationship between πe and the amount of water moved by effective surfactants was found. Temperature changes affect water movement by influencing the surfactant πe and the monolayer state at πe.

Comment on Effect of Temperature on Surfactant-Driven Water Movement in Wet “Unsaturated” Sand

“…Figure qualitatively demonstrates that both myristyl alcohol and butanol can move significant quantities of water, though the two systems exhibit distinct differences. The general behavior observed in the myristyl alcohol experiments (Figure a) is very similar to that reported by Karkare and colleagues ,,, for the same surfactant. Surfactant-induced capillary pressure gradients between the LHS and RHS of the column caused water to drain from the RHS and resulted in wetting of the LHS.…”

“…We have followed with great interest the work of Karkare, Fort, and colleagues related to the ability of surfactants to move water in unsaturated porous media. In their most recent work, Karkare and Fort extend their previous work to include the effect of temperature. They report that the results of the present study support the conclusions of their previous work.…”

“…One-half of the column contained water and surfactant, while the other half was wetted with pure water. Henry et al used the same horizontal column technique and studied the water-moving abilities of myristyl alcohol, one of the low-solubility alcohols used by Karkare and Fort, , as well as those of 1-butanol, a high-solubility alcohol. Water with solid monolayer coverage of myristyl alcohol has a surface tension of approximately 27.1 mN/m .…”

Surfactant‐Induced Flow Phenomena in the Vadose Zone: A Review of Data and Numerical Modeling

“…Karkare et al (1993) applied the closed horizontal column technique to study the ability of 33 surfactants to move water and found that, in order for surfactants to be effective at moving water, “they must be water‐insoluble and must form a condensed solid film at their equilibrium spreading pressure.” Tschapek et al (1984) and Karkare and Fort (2002) reached a similar conclusion. However, Henry et al (1999) showed that surfactant‐induced capillary pressure gradients caused by a high‐solubility alcohol, 1‐butanol, were sufficient to produce effective water movement in the closed soil columns.…”

Solute‐Dependent Capillarity‐Induced Focused Flow during Infiltration into Alcohol‐Contaminated Soil

“…For example, nonuniform surfactant distributions have been shown to cause water to flow in unsaturated, uniformly wetted, closed, horizontal soil columns that would have remained static without surfactants. The observed flow was directly due to capillary pressure gradients caused by concentration‐dependent surface tension differences (e.g., Tschapek and Boggio, 1981; Karkare and Fort, 1993, 2002; Henry et al, 1999, 2001; Henry and Smith 2002; Bashir et al, 2008, 2009).…”