Preparation And Application Of Nano-TiO2Modified Carbon Paste Electrodes

In this paper we use three kinds of modifiers:nano-TiO2, carbon nanotubes and EDTA-Cu(Ⅱ) complex, through single modifier modified and two modifier mixed to modify, prepared three kinds of chemically modified carbon paste electrode for determination of lead, copper, cadmium ions. This paper mainly studies the influence of modifier proportion and experimental conditions on the ability of chemically modified carbon paste electrodes, and in the best experimental condition use the electrodes to determination of lead, copper, cadmium ions. The specific content is the followings:1. Use nano-TiO2modified carbon paste electrode to the determination of Pb2+have very good effect. By use the electrode (graphite quality:nano-TiO2quality=10:5) as working electrode, there was an oxidation peak in the cyclic voltammogram at-0.290V characteristic of Pb2+in0.10mol/L HAc-NaAc buffer (including0.10mol/L KCl) whose pH was5.0when the accumulation time was6min and the potential scan rate was100mV/s. There was a good liner relationship between the peak current and Pb2+concentration in a range of1.0×10-71.0×10-4mol/L with a correlation coefficient of0.9937, and the detection limit was3.7×10-8mol/L.2. Use the carbon nanotubes and nano-TiO2mixed to modify carbon paste electrode whose modifier proportion is graphite quality:carbon nanotubes quality:nano-TiO2quality=10:1:2to the determination of Cu2+have the best effect. In the cyclic voltammogram, there was a characteristic oxidation peak of Cu2+in0.10mol/L HAc-NaAc buffer whose pH was5.5when the accumulation time was200s and the potential scan rate was60mV/s. There was a good liner relationship between the peak current and Cu2+concentration in a range of1.0×10-7～1.0×10-4mol/L with a correlation coefficient of0.9944, and the detection limit was1.43×10-8mol/L3. Use the EDTA-Cu(Ⅱ) complex and nano-TiO2mixed to modify carbon paste electrode whose modifier proportion is graphite quality:EDTA-Cu(Ⅱ) complex quality: nano-TiO2quality=10:1:5to the determination of Cd2+have the best effect. In the cyclic voltammogram, there was a sensitive oxidation peak in0.10mol/L HAc-NaAc buffer (including0.10mol/L KNO3) whose pH was4.5when the accumulation time of Cd2+was10min and the potential scan rate was100mV/s. There was a good liner relationship between the peak current and Cd2+concentration in a range of1.0×10-8～1.0×10-5mol/L with a correlation coefficient of0.9965, and the detection limit was6.1×10-9mol/L.