Foam drainage on thick porous substrate

The use of foam-based applications as a method of drug delivery represents a recent and promising area of research. The interaction of foam and porous substrates have been recently theoretically described using a mathematical model, which combines the equation of foam drainage with that of imbibition of liquid into the porous substrate. Below the drainage of foam placed on chalk experimentally investigated to verify the theory prediction. The surfactants sodium dodecyl sulfate (SDS) and Triton X-100 were used to form a foam. The initial liquid volume fractions of the foam were found to be ranging in between 14.12 and 16.46%. The porosity and permeability of the chalk substrate were experimentally obtained at 59.1% and 3.122.10 -11 m 2 respectively. The height of foam deposited onto the thick porous substrate (chalk) was 2.5 cm and 6 cm. The imbibition into the chalk, the height of foam, and the bubble size within the foam were monitored. The latter enabled the kinetics of the drainage/imbibition to be determined and compared with the predictions according to the theoretical model. The rate of decrease in foam height was initially high and decreased over time as predicted by the theoretical model. All the foam displayed an initial rapid imbibition through the porous substrate, which is again in the agreement with the theory predictions. It was found that solutions with lower surfactant concentrations could penetrate deeper into the chalk. The imbibition front was observed to be uniform: evenly distributed liquid throughout the cross-section of the porous substrate.