Caracterização e aplicação de eletrodos de grafite modificados com cortiça na quantificação de metais pesados em amostras de águas

Abstract

The produced water in oilfield has variable composition, depending on factors as well age and basin geological features. However, the presence of several highly toxic organic and inorganic substances is normal in these effluent discharged by oil industry, and representes a serious enviromental problem, as, depending on its destination (reinjection, discharge or other), there may be contamination of waterbody, air, soil, as well as bioaccumulation trough the food chain: among the contaminants, the heavy metals show up. In order to obey the parameters estabelished by the law and targeting the reduction of environmental damage that may be provoked by theses substances, monitoring techniques need to be studied. In this sense, voltammetry represents a promising option for the quantification of trace metals in situ. That said, the results of this dissertation are divided into two parts: The first article is the study of the electrochemical properties of the electrodes GrRAC-70% and GrRGC-70% from the response obtained by cyclic voltammetry by varying the electrolytes (different pHs) and the presence of electroactive species (anionic or cationic). The second article uses graphite / cork electrodes to quantify lead in water samples. Detection limit of 0.3 µM and linear growth of peak currents was obtained in the concentration range of 0-25 µM. These results were obtained using the square wave anodic stripping voltammetry, which presented better results when compared with the differential pulse anodic stripping voltammetry.