EFFECT OF CLAY CHARGE ON SWELLING - A CLAY-MODIFIED ELECTRODE STUDY

The uniformity of clay films affects the transport of an anionic elect roactive probe through the film. When cations other than Na+ are prese nt in the initial swelling of the him (such as native K+ and Ca2+), or when the native clay is highly charged, internal dislocations of the film, caused by variable stacking domains, enhance the diffusive trans port of Fe(CN)(6)(3-) across the film. This effect is investigated usi ng clay-modified electrodes in which the clays are of variable exchang e forms (Na+, Ca2+, or K+) and variable charge. The charge on the clay is determined both by the native form of the clay and by reduction of structural Fe3+. The results suggest that swelling of clays increases in a linear fashion with CEC, at least for minimally charged clays.