NOTE Adsorption Isotherms of Bitumen/Aqueous Solutions of Intan-100
The spinning drop technique, nevertheless, requires the transparent phase to be the heaviest (6). In our experimental system, the bitumen is heavier Adsorption isotherms for pure bitumen/aqueous solution of the than the water which makes this technique inaccessable to our work. Alternon-ionic surfactant Intan-100 have been determined as a function natively, the bitumen phase has to be diluted in order to make its density of temperature using enhanced video pendant drop technique. The lower than that of water, or else heavy water (D 2 O) has to be used (7).
area/molecule occupied by the surfactant at the bitumen/water
In both cases, spurious effects on surfactant adsorption can not be ruled interface is about 3 times higher at 30ЊC than at 60ЊC at which out (8).
maximum packing occurs. Isotherms for the model system hep-
The aim of this study is to present, for the first time, adsorption isotherms tane/aqueous solutions of Intan-100 indicate that maximum packand values of area/molecule for the system pure bitumen/aqueous solution ing is not possible in the temperature range 20-60ЊC. This fact of Intan-100 determined at the three temperatures of 30, 45, and 60ЊC by implies that bitumen/water interface is a unique system where the employing the video enhanced pendant drop technique. natural surfactant present in the bitumen is playing a competitive role at the interface.