The interfacial behavior of 2-hydroxy-5-nonylbenzophenone oxime (HBPO) at the air/water interface has been investigated with Langmuir trough techniques. The dissolution kinetics of HBPO followed a diffusion-controlled model from which the aqueous solubility of HBPO was estimated. Because of deprotonation of the hydroxyoxime group, the aqueous solubility of HBPO was pH dependent. At pH 2.0, the solubility was 0.1 μmole dm-3 and increased to 4.0 μmole dm-3 at pH 12. From the influence of pH on the dissolution rate, the surface pKa for HBPO was estimated to be 11.5. At surface pressures greater than the equilibrium spreading pressure of HBPO (23 mN m-1), simultaneous dissolution and monolayer collapse were observed.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Surfaces, Coatings and Films
- Colloid and Surface Chemistry