Adsorption Kinetics of Alkylphosphine Oxides at Water/Hexane Interface
A pendant drop technique has been used to study the adsorption of a nonionic surfactant, an alkyldimethylphosphine oxide (C13DMPO), at the water/hexane interface. The measured interfacial tensions exhibit a steep initial decrease, pass through a minimum, and then level off at a value which depends on the initial surfactant concentration in the drop. This time dependence of the interfacial tension can be interpreted by an adsorption with a subsequent transfer of the surfactant into the second bulk phase, hexane. Measurements of the distribution coefficient show that the solubility of C13DMPO is much higher in hexane than in water. A qualitative model is proposed which describes the observed dynamic interfacial tensions.
Ferrari
M
Max-Planck-Institut fur Kolloid- und Grenzflachenforschung, Rudower Chaussee 5, Berlin-Adlershof, D-12489, Germany
Liggieri
L
Ravera
F
Amodio
C
Miller
R