Adsorption of phenosafranin at the water ∣ 1,2 DCE interface: a voltammetric approach

In the present paper the interfacial behavior of a cationic dye, phenosafranin (PhS+), is voltammetrically analyzed. A sharp and narrow peak during the negative sweep was observed. The dependence of this peak on concentration, sweep rate and switch potential was a clear indication of an adsorption–desorption process similar to those observed on solid electrodes. It was determined that the adsorbed species results from the ion pairing between dicarbollylcobaltate (DCC−) and PhS+ at the interface as the process is observed only when the interface is polarized at the potential transfer of DCC−. The process fitted with a Frumkin isotherm and indicated a strong attractive interaction (g=−2.3) between the adsorbed species. This interaction was also analyzed spectrophotometrically.