R. Aveyard et al., DISPLACEMENT OF OIL BY AQUEOUS SURFACTANT SOLUTIONS FROM CAPILLARIES SEALED AT ONE END, Colloids and surfaces. A, Physicochemical and engineering aspects, 113(3), 1996, pp. 295-307
We have investigated the displacement of oil (decane and nonane) by su
rfactant solutions from horizontal capillaries sealed at one end. Oil
displacement occurs when the hydrostatic pressure is sufficient to ove
rcome the Laplace pressure arisng from the curvature of the oil-water
interface which is deformed due to gravity. Displacement is possible w
hen the oil-water tension is less than a certain critical value gamma(
crit). We derive an approximate equation for gamma(crit) in terms of t
he capillary radius, the liquid densities and the effective values of
the contact angle of the liquid-liquid interface with the wall of the
capillary. The equation is found to provide a satisfactory prediction
of the feasibility of oil displacement. The rate of displacement is an
alysed using a modification of Washburn's treatment of penetration of
capillaries by liquids in which it is assumed that all of the energy d
issipation occurs within the bulk liquids rather than at the interface
. Satisfactory agreement with experimental displacement rate measureme
nts is found.