Effect of Clay Charge on Swelling: A Clay-Modified Electrode Study

Abstract

Abstract The uniformity of clay films affects the transport of an anionic electroactive probe through the film. When cations other than Na+ are present in the initial swelling of the film (such as native K+ and Ca 2+ ), or when the native clay is highly charged, internal dislocations of the film, caused by variable stacking domains, enhance the diffusive transport of Fe(CN) 6 3− across the film. This effect is investigated using clay-modified electrodes in which the clays are of variable exchange forms (Na+, Ca 2+ , 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 Fe 3+ . The results suggest that swelling of clays increases in a linear fashion with CEC, at least for minimally charged clays.