碳纳米管糊电极阴极溶出伏安法测定油品中镍含量

Determination of Nickel in Oil Product by Novel Cathodic Stripping Voltammetry With Carbon Nanotube Paste Electrode

在0.10mol/L NaOH和4.0×10-5 mol/L丁二酮肟溶液中,Ni(Ⅱ)在电位0.80V被氧化为Ni(Ⅲ)而富集于电极表面,随后在正电位窗口中阴极溶出,据此拟定了用碳纳米管糊电极阴极溶出伏安法测定镍含量的新方法,探讨了Ni(Ⅱ)溶出峰的电化学性质,优化了测定条件。结果表明,与碳糊电极相比,碳纳米管糊电极对溶出峰的伏安响应过电位减小、峰电流增大,具有电催化作用。当富集时间为120s时,方波阴极溶出伏安峰电流与Ni(Ⅱ)浓度在8.0×10-9～1.0×10-5 mol/L范围内呈线性关系,检出限为3.5×10-9 mol/L。采用本法测定了油品中的镍含量,结果满意。

A novel cathodic stripping voltammetric method with a multiwall carbon nanotube paste electrode （MWCNT-PE） for the determination of nickel was proposed. In 0.10 mol/L NaOH solution containing 4. 0 ×10-5 mol/L dimethylglyoxime （DMG）, Ni （Ⅱ ） was first effectively enriched on the surface of electrode by oxidation to Ni（ Ⅲ ） at potential of 0.80 V （versus SCE）, and then determined by cathodic stripping voltammetry （CSV） at positive potential windows. The electrochemical properties and the producing condition of the stripping wave of Ni （Ⅱ） were discussed. Compared with carbon paste electrode, MWCNT-PE had electrocatalytic effect on the voltammetric responses of Ni（ Ⅱ ） since the enhanced peak current and the decreased overpotential. Under the optimized experimental conditions, the square-wave voltammetric peak current of the cathodic stripping wave was proportional to the molar concentration of nickel in the range of 8.0 × 10- 9 -1. 0 × 10-5 mol/L with 120 s of accumulation. The detection limit was 3.5× 10-9 mol/L. By using the proposed method, nickel mass fraction in oil products was evaluated and the results were satisfactory.