Influence of stearic acid monolayers upon the procaine adsorption from underlying alkaline aqueous solutions.
Adsorption of procaine at the air/water interface and its penetration into stearic acid monolayers from aqueous subphase of pH 8 are studied by measuring surface tension of aqueous procaine solutions and by recording surface pressure vs. mean molecular area curves for stearic acid monolayers spread onto procaine solutions of different concentrations. The amount of procaine in the interface is derived by means of Gibbs' equation. Results are compared to those obtained earlier at pH 2 and on unbuffered subphases. With increasing pH an increasing procaine adsorption and procaine penetration is observed. This phenomenon is interpreted in terms of protolytic equilibria in which participate both surfactants procaine and stearic acid.
Zsakó
J
J
Department of Physical Chemistry, University of Cluj-Napoca, Romania.
Tomoaia-Cotişel
M
M
Chifu
E
E
Mocanu
A
A
Frangopol
P T
PT
D000327:Adsorption; D006863:Hydrogen-Ion Concentration; D008567:Membranes, Artificial; D011343:Procaine; D012996:Solutions; D013229:Stearic Acids; D013500:Surface Tension
D008567:Membranes, Artificial; D012996:Solutions; D013229:Stearic Acids; D011343:Procaine