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新型锡铋合金电极检测重金属应用研究
张丽
Subtype硕士
Thesis Advisor潘大为
2012-05-21
Degree Grantor中国科学院研究生院
Place of Conferral北京
Degree Discipline海洋化学
Keyword锡铋合金电极 溶出伏安法 重金属检测
Other Abstract

随着工农业的迅速发展,重金属污染出现了由工业向农业、城区向农村,水土污染到食品链的转移,水体、土壤以及食品等受重金属的污染日益严重。重金属不可降解导致其在环境中不断积累,其造成的污染也正在进入突发性、连锁性和区域性的爆发阶段,不仅对环境生态系统造成破坏,还对人类健康构成威胁。因此,重金属污染问题已经引起了世界各国政府部门以及科学家们的高度重视,发展快速、准确的重金属检测方法和技术显得尤为重要。

目前,国际上重金属检测方法逐渐向现场、快速、实时、在线、连续和自动化测量方向发展。常用重金属检测方法的仪器设备往往价格昂贵、操作复杂、分析测试及维护费用高,无法满足重金属实时、快速检测的需要。而电化学方法中的溶出伏安法以其极低的检测下限、多元素识别能力以及现场实时在线检测分析的特性在痕量分析中占有越来越重要的地位。电极材料的选择是溶出伏安分析法的核心问题,其直接决定着分析检测性能。该方法中常采用的汞电极具有剧烈的毒性,经常使用易对环境造成二次污染。常用固体电极的表面易于吸附其他物质,长时间使用后,其表面会发生化学或物理变化,致使检测结果的稳定性和准确性大大降低。固态汞合金电极寿命长,可连续使用几个星期,适合于远程或无人值守情况下的实时监测分析,但是由于电极制作以及电极处理过程都无法避免汞的使用。近年来,铋作为一种环保型电极材料备受电化学工作者的青睐,金属铋能与多种被测重金属形成二元或多元合金,分析性能与汞相当,但是铋电极也存在许多亟待解决的难题,如预镀铋膜电极在转移过程中极易被氧化,原位镀膜电极铋离子易发生水解,铋棒电极制作工艺极其复杂且易被氧化等。

因此,本论文提出了一种新型锡铋合金电极材料。新型锡铋合金电极环境友好、电极制备过程极其简单、分析成本低廉,是一种极具潜力的电极材料。本文将溶出伏安分析法与锡铋合金电极相结合,将其成功应用于重金属锌、镉、钴的分析检测中。主要内容包括以下几个方面:

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。
2、锡铋合金电极结合阳极溶出伏安法对重金属镉(Cd)进行检测。本实验采用了循环伏安对电极表面进行重组活化得到了低的检出限。并且采用此方法,发现在含镉的醋酸缓冲体系中连续测量40次电极无退化现象,40次连续测量的相对标准偏差为2.4%,表明此电极在现场连续自动化监测方面具有较好的应用潜力。将其应用于环境污染问题“镉米”的研究,检测结果与电感耦合等离子体质谱检测结果很好的吻合,检测结果令人满意。
3、锡铋合金电极结合吸附溶出伏安法对重金属钴(Co)进行检测研究。本实验将1,2-环己二酮二肟(nioxime)作为钴离子的络合剂,亚硝酸根离子作为氧化剂,对钴在锡铋合金电极表面的吸附溶出行为进行了考查。在0.1 M的氨缓冲溶液中,富集时间为60 s条件下,实验得到锡铋合金电极对钴的检测线性范围为0.2 ~ 20 nM,最低检出限为44 pM。锡铋合金电极结合吸附溶出伏安法为环境水样中钴的检测提供了一个良好的检测平台。
 

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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 () 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.

Subject Area分析化学
Language中文
Document Type学位论文
Identifierhttp://ir.yic.ac.cn/handle/133337/5657
Collection中科院烟台海岸带研究所知识产出_学位论文
Recommended Citation
GB/T 7714
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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