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

Measurements of the surface tension of aqueous solutions of Triton X-1 00 (TX-100) were made at different temperatures. Isotherms and thermod ynamic 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 betwee n 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 energ y of adsorption gave slightly different results. In the region of low concentration the Pi(A - A(0)) values were equal to 1kT. At high conce ntration there were attractive Lifshitz-van der Waals forces between t he apolar parts of the TX-100 molecules and repulsive acid-base forces between the heads of the TX-100 molecules in the adsorbed monolayer f ilm.