ADSORPTION OF BETA-CYCLODEXTRIN AT THE POLYCRYSTALLINE GOLD ELECTRODE AQUEOUS-SOLUTION INTERFACE

The adsorption of β-cyclodextrin, β-CD, on a polycrystalline gold electrode has been studied in NaClO4, LiClO4 and Na2SO4 dilute solutions by impedance measurements. The adsorption of β-CD is similar to that for other organic compounds such as dimethylsulphoxide. β-CD is a strong adsorbate, half coverage (θ/2) being reached in solutions containing less than 5×10-5 mol dm-3. It was shown that the main symmetry axis of the adsorbed β-CD molecule is oriented perpendicular to the electrode surface. The adsorption of β-CD on the polycrystalline gold electrode follows a Langmuir isotherm with \ ̄gDGmaxo = -34.70 ± 0.57 kJ mol-. The observed behaviour has been compared with the literature data for β-CD adsorption on the Hg electrode. © 1990.