EFFECT OF CLAY TYPE ON THE DIFFUSIONAL PROPERTIES OF A CLAY-MODIFIED ELECTRODE

The response of two swelling clays (SWy-1 and SAz-1) and of one non-sw elling clay (KGa-1) and of a series of mixtures of these clays to diff erent electrolyte concentrations was examined using clay-modified elec trode techniques. A non-interacting probe ion, Fe(CN)(6)(3-) was monit ored via reduction for its arrival at a Pt electrode coated with thin films of the clay mixtures. The three clays had both different tempora l responses and different equilibrium currents. For SWy-1 the currents were developed over time and were dependent upon the electrolyte of t he bathing solution, which was consistent with X-ray diffraction data literature for the interlayer dimension. Similar behavior was found fo r SAz-1, but for KGa-1, currents were instantaneous and were independe nt of the bathing electrolyte. This suggests that the pores controllin g the probe ion transport were between particle or pinhole in nature. When mixtures of the clays were examined, it was found that KGa-1 caus ed defects within the structures of the mixed clay films. The SWy-1 mi xture was not as affected by these disruptions as was the SAz-1 mixtur e.