Adsorption of Intan-100 at the bitumen/aqueous solution interface studied by spinning drop tensiometry

We present an experimental study on the adsorption behaviour of Intan-100, a non-ionic surfactant, at the bitumen/water interface when the density difference between the two phases is increased by diluting the crude oil with 10% xylene by weight or using heavy water (deuterium oxide) as the aqueous phase. The equilibrium interfacial tension, surface excess and critical micelle concentration of Intan-100, at 30, 60 and 75°C, are determined using a spinning drop tensiometer, which gives fast and accurate results for low and high values of tension. Comparison with previously published data indicate that the use of heavy water is to be preferred over dilution of the heavy crude oil when the densities of the two phases are closely matched.