The Adsorption of Tetramethylthiourea at the Interface Electrode – NaClO4 in the Presence of Sodium 1-decanesulfonate

Mixed adsorption layers properties made by two organic substances in which 1-decanesulfonic acid sodium salt undergoes physical adsorption and tetramethylthoiurea (TMTU) chemical adsorption in 1M NaClO4 on the mercury electrode are described. Based on differential capacity data – potential curves obtained at mercury electrode the double layers TMTU adsorption parameters were calculated whereas the adsorption constants were derived from pressure data as a function of electrode charge density and TMTU’s bulk concentration. The interaction parameters point to weak repulsive interaction between the adsorbed TMTU molecules. The free adsorption energy was clearly smaller than in the detergent’s absence. The potential drop rectilinear segments across the inner layer dependence on the relative surface excess were analyzed in order to calculate the electrostatic parameters of the inner layer. Zn2+ ions reduction in kinetic studies provided information concerning adsorption equilibrium at potentials distant from adsorption maximum.