The Properties And Application Of Chemically Modified Bismuth Film Electrode

Electrochemical stripping analysis has always been recognized as a powerful tool for measuring trace metals. Its remarkable sensitivity is attributed to the combination of an effective preconcentration step with advanced measurement procedures that generates an extremely favorable signal-to-background ratio. Mercury electrodes have been accepted as the widely used electrode material choice. However, the toxicity of mercury and its compounds makes its less and less popular. Bismuth film electrodes （BiFEs） have been gained much interest due to its environmental friendly, reasonably wide potential window, and partial insensitivity to dissolved oxygen as well as ability to form alloys with heavy metals. Recently, the novel materials such as polyelectrolyte and nanomaterials have been widely used to prepare chemically modified electrodes and biosensors because of their special characteristics, which expand the field of the electrode materials and electrochemical research. Chemically modified electrodes with excellent performances can be prepared by suitable modification. In this dissertation, a serial of midified BiFEs have been fabricated based on the electrodeposition strategy with new materials such as Nafion and graphite nanofibers. Thus-prepared bismuth films exhibit high sensitivity and good selectivity. The main points of this dissertation are addressed as follows:1. A bismuth-film modified graphite nanofibers-Nafion glassy carbon electrode （BiF/GNFs-NA/GCE） was constructed for the simultaneous determination of trace Cd（II） and Pb（II）. The electrochemical properties and applications of the modified electrode were studied. Operational parameters such as deposition potential, deposition time and bismuth ion concentration were optimized for the purpose of determination of trace metal ions in 0.10 M acetate buffer solution （pH 4.5）. Under optimal conditions, based on three times the standard deviation of the baseline, the limits of detection were 0.09μg L^-1 for Cd（II） and 0.02μg L^-1 for Pb（II） with a 10 min preconcentration. In addition, the BiF/GNFs-NA/GCE displayed good reproducibility and selectivity, making it suitable for the simultaneous determination of Cd（II） and Pb（II） in real sample such as river water and human blood samples.2. Bismuth film electrodes are widely used for determination of heavy metal ions in acidic solutions, while alkaline solutions are rarely employed. Scanning electron microscope （SEM） and electrochemical experiments were tested the NA-BiFE electrochemical properties in alkaline and acidic solutions, respectively. Under optimal conditions, the as-prepared modified electrodes were applied to detect heavy metal lead by differential pulse stripping voltametric method in alkaline buffer and acidic solutions, respectively. The modified electrode was used to determine heavy metal ions in both alkaline and acidic solutions, and the results of the method agree well with those of atomic absorption spectroscopy.