Dorota Gugała-Fekner

Mixed adsorption layers of 0.1 M tert-butanol-tetramethylthiourea at the interface of Hg/aqueous perchlorate solutions.

The electrosorption behavior of tetramethylthiourea (TMTU) on a mercury electrode from 1.0, 0.5, and 0.1 M NaClO(4) solutions containing 0.1 M tert-butanol (TB) is described by means of adsorption isotherm constants. The adsorption parameters for the double layer were calculated from a double-layer differential capacity measurement extrapolated to zero frequency. The values of the relative surface excess increase along with the concentration of NaClO(4). It seems that the adsorption of TMTU is determined by an interaction between adsorbed molecules. The presence of TB in the adsorption layer distinctly influences the parameters of the inner layer.

Adsorption of adenine on mercury electrode in acetate buffer at pH 5 and pH 6 and its effect on electroreduction of zinc ions

The measurements of double-layer differential capacitance, zero charge potential, and surface tension at that potential allowed us to examine the adsorption properties of adenine on the mercury surface from the neat buffer solution, i.e., the acetate buffer at pH 5 and pH 6. The systems obtained at such pH values were close to physiological fluids in their characteristics. The adsorption energy and interaction constants were determined using Frumkin isotherm and virial isotherm. It was shown that the adenine molecule is adsorbed on the mercury electrode with its negative pole against the electrode surface. Using the cyclic voltammetry technique and measuring Faraday impedance, an increasing effect of adenine on the kinetics of zinc ion electroreduction was found. In both buffer solutions, the neutral adenine molecules can form on the surface of the working electrode, an unstable active complex with depolarizer ions, facilitating electron exchange.Graphical abstract