|Place of Conferral||北京|
|Keyword||锡铋合金电极 溶出伏安法 重金属检测 锌 镉 钴|
|Other Abstract|| |
1. 锡铋合金电极结合阳极溶出伏安法对重金属锌（Zn）进行检测。本实验采用自制锡铋合金电极，采用直接切割以实现表面更新的方法，旨在实现对锌的低成本、一次性检测目的。锡铋合金电极具有较高的氢过电位，非常适合电极电位较负的金属离子锌的检测分析。结果表明：在0.5 ~ 25 μM 浓度范围锌离子浓度与溶出峰电流具有良好的线性关系，理论检出限为50 nM。新型锡铋合金电极作为一种新型固体圆盘电极，为酒及蜂蜜中锌离子的检测提供了一个良好的平台。
With the rapid development of industry and agriculture, heavy metal pollution has extended from industry to agriculture, urban areas to rural areas and water and soil pollution to the food chain pollution. Owing to heavy metals contamination, environmental waters, soil and food pollutions are becoming more and more severe. They are gradually accumulated in environment due to the non-degradability of heavy metals. Therefore, heavy metal pollution has been entering an outbreak period with suddenness, linksystem and regionalisation. Not only does heavy metal pollution destroy ecological system, but also is harmful to human health. Therefore, heavy metal pollution has got great attention of government worldwide and scientists and development of rapid and accurate detection of heavy metals has become very necessary.
To date, heavy metal detection has gradually tended to be on-site, fast, real-time, on-line, continuously and automatically. The instruments of common methods of heavy metal determination are not only cumbersome and expensive, but also require complicated operation and high cost of testing and maintenance, which can't meet the growing demands of the fast and real-time heavy metal detection. With low detection limit, multi-element recognition and real-time field detection, stripping voltammetry plays a more and more important role in detecting trace heavy metals. The core of stripping voltammetric analysis is the choice of electrode materials which directly determined the performance of analytical detection. The usual usage of mercury electrode in stripping voltammetric analysis with strong toxicity can easily cause secondary pollution to the environment. Moreover, the solid electrodes polluted by other substance easily will make chemical or physical changes on the surfaces after a long period of using, which causes a great deterioration of both the accuracy and stability. Solid amalgam electrode used continuously for several weeks or more is suitable for remote, automatical and real-time monitoring analysis. However, owing to the inevitable usage of mercury in the electrode production or dispose, it is harmful to the operator and environment. Recently, due to its environmentally friendly property and closest behavior to mercury, bismuth (Bi) has been suggested as an alternative electrode material of mercury in ASV for heavy metal determination. The excellent analytical characteristic combined with low toxicity of Bi has led to widespread use of this material. However, ex situ Bi film electrode is easily oxidized once in contact with air, which results in relatively low chemical stability. For in situ Bi film electrode, Bi (Ⅲ) ions are easily hydrolyzed by forming insoluble compounds and limited by many practical application. For bismuth bulk electrode, it is relatively complicated to fabricate due to the fragileness of bismuth.
Thus, in this paper, a novel tin-bismuth alloy electrode was proposed for heavy metal determination. With convenient preparation and low costs of detection, the new environmental friendly tin-bismuth alloy electrode is much potential for stripping analysis. Combined with the stripping voltammetry analysis, the tin-bismuth alloy electrode was successfully used in heavy metal ions (such as zinc, cadmium, cobalt) determination. The main contents are as follows:
1. The tin-bismuth alloy electrode was used for anodic stripping determination of zinc. Based on the soft characteristics of tin-bismuth alloy electrode, the homemade electrode surface can be renewed by cutting directly after each experiment. The electrode has high hydrogen overvoltage, which is especially suitable for the anodic stripping analysis of zinc. Experiment results showed a good linear relationship between the oxidation peak current and the concentration of Zn2+ in the range of 0.5 ~ 25 μM and a low detection limit of 50 nM was obtained. Additionally, experiments also demonstrated that, as a new type of solid disc electrodes, this electrode was suitable for determination of zinc in honeys and wines.
2. The tin-bismuth alloy electrode was used for anodic stripping voltammetry determination of cadmium. The electrode surface recombined and activated by cyclic voltammetry got a lower detection limit. Moreover, the electrode has not been degraded after 40 repetitive measurements of Cd2+ with a relative standard deviation of 2.4%, which suggested a great potential capacity for the field, continuous and automatical heavy metal monitoring. Then, it was applied to study of environment pollution of "cadmium rice", the results obtained from this electrode are in accordance well with those detected by ICP-MS.
3. The tin-bismuth alloy electrode was used for adsorptive stripping voltammetric determination of cobalt. With 1,2-cyclohexanedione (nioxime) used as complex agent of cobalt, nitrite ions used as catalysts and oxidizing reagents, the adsorptive stripping voltammetric behavior of cobalt on the alloy electrode surface was studied. With 0.1 M ammonia buffer and 60 s accumulative time, the linear range of the electrode to cobalt determination is 0.2 ~ 20 nM and a low detection limit of 44 pM was obtained. Experiments showed that the tin-bismuth alloy electrode combined with adsorptive stripping voltammetry can be adopted for determination of cobalt in environmental water samples.
|张丽. 新型锡铋合金电极检测重金属应用研究[D]. 北京. 中国科学院研究生院,2012.|
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