ANALYSIS OF VOLTAMMETRIC CURRENTS IN CONCENTRATED ORGANIC REDOX SOLUTIONS USING THE CULLINAN-VIGNES EQUATION AND ACTIVITY-CORRECTED MUTUAL DIFFUSION-COEFFICIENTS

Diffusion-limited voltammetric currents for the 1-e(-) reduction of ni trobenzene (NB) in acetonitrile (AN) over the entire composition range (0 less than or equal to x(NB) less than or equal to 1, x(NB) mole fr action of NE) were analyzed employing the Cullinan-Vignes equation to describe the interdiffusion of the redox species and solvent. Activity -corrected mutual diffusion coefficients at 45 degrees C were computed from isothermal liquid-vapor equilibrium data and steady-state limiti ng currents, I-lim, for NE reduction at a 12.5 mu m-radius Pt microdis k electrode. Application of activity-corrected mutual diffusivities in the Cullinan-Vignes equation appears to account properly for non-idea l behavior of I-lim for x(NB) > similar to 0.4. Values of I-lim are 'o ver-corrected' by activity data to a small extent for x(NB) < 0.4, sug gesting the self-association (i.e., clustering) of solution components . (C) 1997 Elsevier Science S.A.