V. Vacheva et al., APPLICATION OF A 2-STATE ADSORPTION-ISOTHERM TO THE ELECTROSORPTION OF DODECYLDIPHENYLPHOSPHINE OXIDE ON MERCURY, Langmuir, 11(11), 1995, pp. 4564-4567
The adequacy of a molecular model to describe the adsorption of dodecy
ldiphenylphosphine oxide (DDPO) at a mercury electrode has been checke
d; the model explicitly treats the electrostatic and nonelectrostatic
interactions in the adsorption layer on a molecular level and is based
on a two-state adsorption isotherm derived by Sangaranarayanan and Ra
ngarajan. Estimates of the adsorption parameters have been obtained on
the basis of a method applying nonlinear regression analysis and an e
xperimental sample for the decrease in the interfacial free energy wit
h the addition of surfactant, as a function of electrode charge densit
y and surfactant concentration. A critical discussion of the obtained
parameters has been made. Finally an important restriction which shoul
d be imposed on adsorption parameters when applying the model has been
elucidated and the peculiarities of the model have been shown if this
restriction is not fulfilled.