Potencialidades do dióxido de chumbo eletrodepositado como sensor potenciométrico

Abstract

This paper proposes an experiment to be performed in both instrumental analysis and experimental physical-chemistry curricular disciplines in order to open options to develop challenging basic research activities. Thus the experimental procedures and the results obtained in the preparation of electrodeposited lead dioxide onto graphite and its evaluation as potentiometric sensor for H3O+ and Pb2+ ions, are presented. The data obtained in acid-base titrations were compared with those of the traditional combination glass electrode at the same conditions. Although a linear sub-Nernstian response to free hydrogen ions was observed for the electrodeposited PbO2 electrode, a good agreement was obtained between them. Working as lead(II) sensing electrode, the PbO2 showed a linear sub-Nernstian behavior at total Pb2+ concentrations ranging from 3,5 × 10-4 to 3,0 × 10-2 mol/L in nitrate media. For the redox couple PbO2/Pb(II) the operational slope converges to the theoretical one, as the acidity of the working solution increases.