Spherical diffusion and shielding effects in reverse pulse voltammetry

Dynamics of trace metal sorption by an ion-exchange chelating resin described by a mixed intraparticle/film diffusion transport model. The Cd/Chelex case

“…Eqn. 12is parallel to other approaches where semi-infinite diffusion in the spherical domain is assumed [40][41][42].…”

Multimode triple sampling polarography in the study of amalgamation and sphericity effects at the static mercury drop electrode

“…Current responses and half-wave potentials, used for comparisons with the experimental values, were calculated by use of eq 2 in the theoretical section. The diffusion coefficients used in these calculations were as follows: for lead, D0 = 0.72 X 10"9 m2/s (15), for cadmium, D0 = 0.73 X 10~9 m2/s (16), and for iron, D0 = 0.70 X 10~9 m2/s (15). The Dr value used for lead was 1.17 x 10"9 m2/s (15) while that of cadmium was 1.66 X 10™9 m2/s (16).…”

“…All these complications make theoretical predictions for current responses of the SMDE difficult. These problems could, however, be overcome if the potential is not applied until drop growth, and the convection following drop growth, has ceased (11,15). In order to be able to make theoretical predictions of the current responses and half-wave potentials for NPP and DCP at a SMDE, the effects of amalgam formation and sphericity upon the shapes of the polarograms need to be considered.…”

Impact of spherical diffusion on labile trace metal speciation by electrochemical stripping techniques

“…Also in the case of reverse pulse polarography (RPP), a technique that has some similarities with stripping voltammetry, Osteryoung and co-workers [13,14] provided a quantitative description of spherical diffusion and capillary shielding effects. For double-step chronoamperometry in amalgam forming systems with long pulse durations at spherical electrodes, Galvez [15] proposed the inclusion of spherical corrections in the theory to explain large discrepancies between earlier theoretical predictions and experimental results.…”