Adsorption of optically active dibenzoyltartaric acid on the dropping mercury electrode

Abstract

Adsorption on mercury of D–, L-, and DL-dibenzoyltartaric acid (DBTA) from aqueous 0.1 N HCl solution has been investigated using the drop-time technique. Electrocapillary curves of the racemate were different from those of the two optical isomers. By applying the Gibbs isotherm to the electrocapillary data at E=–0.4 V, the Γ_max value related to DL-DBTA was found to be higher than the corresponding Γ_max value for L-(or D-) DBTA. Noticeable deviations from the Langmuir isotherm were detected. Our results suggest that an optically active substance can arrange itself in the adsorbed layer in different ways depending upon its presence in solution as an optically active from or as a racemic mixture.