THE ADSORPTION OF TRITON X-100 AT THE AIR-AQUEOUS SOLUTION INTERFACE

Measurements of the surface tension of aqueous solutions of Triton X-100 (TX-100) were made at different temperatures. Isotherms and thermodynamic adsorption parameters were determined from the surface tensions. Also, the-equation of state for the monolayer film of TX-100 at the water-air interface was analyzed. A linear dependence was found between log Gamma and log C in the region of low concentration of TX-100 in solution, and three different methods used to calculate the free energy of adsorption gave slightly different results. In the region of low concentration the Pi(A - A(0)) values were equal to 1kT. At high concentration there were attractive Lifshitz-van der Waals forces between the apolar parts of the TX-100 molecules and repulsive acid-base forces between the heads of the TX-100 molecules in the adsorbed monolayer film.