versão impressa ISSN 0016-7169
We are hereby presenting the results obtained from a study on using Microparticle Voltammetry (MPV) for identifying Iron oxides and oxy-hydroxides. This technique allowed us to distinguish different mineral species, such as hematite, goethite, magnetite and maghemite, in both synthetic and natural samples. By measuring synthetic pigments at different temperatures, evidence was found of an electrochemical behavioral pattern which allowed differenciating them. The current peak location (potential value) proved to vary according to the mineral species, grain size and chrystallinity degree. The area varies in terms of electroactive concentration of the species given. Width varies according to particle size distribution. In high iron oxide and oxy-hydroxide concentration samples, peaks were defined at current values of mA (milliampers) and in paleosol samples having an overall iron content lower than 6%, peaks were recorded at currents of µA (microampers). Therefore, a possibility arises of applying this technique to environmental and palaeo-environmental studies of these minerals. MPVs main advantages compared to conventional methods are speed and simplicity as well as the fact that it allows processing a few sample grains, in spite of its chrystallinity degree. Unlike magnetic methods - strongly influenced by the presence of magnetite- MPV is highly sensitive for detecting weakly magnetic species.
Palavras-chave : Microparticle voltammetry; current peak potential; Iron oxides and oxy-hydroxides.