Interfacial tension studies at the aqueous urea- n-decane and aqueous urea + surfactant- n-decane interfaces

Abstract

Interfacial tension measurements are reported on the aqueous urea- n-decane interface over a range of temperature from 15 to 50°C and a range of urea concentration from 1 to 12.8 m. It is found that urea is positively adsorbed at the interface and that the area per urea molecule lies in the range 200 to 300 Å 2. The integral enthalpy of adsorption is found to be very temperature dependent. The implication of these observations to the stability of hydrophobic bonds in protein molecules is discussed. Some measurements on the effect of urea on the adsorption of n-dodecyltrimethylammonium bromide at the aqueous- n-decane interface are also reported.