A radiometric study of thallium adsorption on gold electrode

Thallium surface concentration on a gold electrodeposit in 10-5 M Tl+ + 0.1 M KOH solution as a function of electrode potential was measured by radioactive labelling (204Tl) method. At potential just anodic to to the Nernst potential of the reaction Tl/Tl+ the surface concentration of thallium on gold is close to a dense monolayer. With the potential change to the positive direction, the thallium desorption takes place, however the thallium surface concentration does not reach zero up to the Nernst potential of the Tl+/Tl3+ reaction, from which this concentration starts to increase with the potential. The positive going branch of the potential dependence of thallium equilibrium adsorption on gold electrodeposit is somewhat above the negative going branch. At 10-5 m Tl+, the thallium adsorption equilibrium is attained within 10 minutes. (author). 5 figs., 49 refs