基于差分脉冲阳极溶出伏安法的土壤重金属铜检测研究

发布时间：2018-06-13 15:54

本文选题：溶出伏安法 + 丝网印刷金电极　；参考：《山西农业大学》2016年硕士论文

【摘要】：重金属不仅污染土壤、水体及大气环境,还污染畜产品、水生生物及农作物等,因此,在环境、食品、药物、农药残留等方面,检测分析重金属一直是分析工作者关注和研究的课题之一,基于传统检测重金属的方法往往存在仪器设备大型昂贵、实验步骤操作复杂、需要有经验的操作者操作等问题,本研究尝试采用电化学分析方法中的差分脉冲阳极溶出伏安法,利用修饰液修饰过的丝网印刷金电极来检测土壤重金属铜的含量,具体工作如下：(1)为了改善电极表面的电化学特性,本研究将原丝网印刷金电极放入稀硫酸溶液中进行循环伏安扫描活化处理,然后观察分析其在铁氰化钾溶液中的循环伏安曲线图,得出：较未活化的丝网印刷金电极,活化后的电极其氧化峰和还原峰电位差值变小,峰电流变大,表明活化后的丝网印刷金电极其电化学性能增强。(2)为了提高测定土壤重金属的灵敏度,适应定量、快速的测定要求,本研究观察分析了丝网印刷金电极,铋修饰的丝网印刷金电极,Nafion (0.1%)修饰的丝网印刷金电极,铋/Nafion修饰的丝网印刷金电极在铁氰化钾溶液中的循环伏安扫描曲线,得出：较未修饰的丝网印刷金电极,修饰液修饰过的电极其电化学性能均有增强,并且铋/Nafion修饰的丝网印刷金电极电化学性能明显增强,其氧化峰与还原峰的电压差值最小,峰电流值也最大。(3)为了获得实验的最优参数,本研究采用差分脉冲阳极溶出伏安法,铋/Nafion修饰的丝网印刷金电极测量一定浓度的标准铜溶液。基于前人研究的基础,据测得的重金属铜含量大小,通过控制变量法设置实验的各个参数,得出实验的最佳沉积时间360s、沉积电势-0.7 V、静止时间10s、溶出电位0.6V、清洗电位0.8 V、清洗时间30 s、电解质HAc-NaAc溶液PH=2、铋溶液浓度6000 ug/L、Naf ion溶液体积4ul,并绘制了铜浓度-电流的标准曲线图,其线性回归方程为Y=6.54833+0.00505x,线性相关系数大于0.9926。(4)为了实现对实际土壤样本重金属铜的测量,本研究首先将实际土样经过湿法消解,过滤配置成相应的土壤溶液,然后利用最优参数结合标准曲线图,应用差分脉冲阳极溶出伏安法测量实际土壤样本中的重金属铜的含量,最后将测得的土壤重金属铜含量与采用国际标准法原子分光光度计测量的相同土壤中的重金属铜含量进行比较分析,发现两者检测结果基本一致,说明该电化学检测方法具有较好的准确性,抗干扰能力强,分析速度快,成本低、对环境无污染,适合于土壤重金属的检测。
[Abstract]:Heavy metals not only pollute the soil, water and atmospheric environment, but also pollute animal products, aquatic organisms and crops. Therefore, it is one of the subjects of concern and research to detect and analyze heavy metals in the environment, food, medicine and pesticide residues. The experimental procedure is complicated and requires experienced operators. This study attempts to use the differential pulse anodic stripping method in electrochemical analysis to detect the content of heavy metal copper in soil by modified silk screen printing gold electrode. The specific work is as follows: (1) to improve the electrochemical characteristics of the electrode surface. In this study, the original silk screen printed gold electrode was activated by cyclic voltammetry in dilute sulfuric acid solution, and then the cyclic voltammetry curve of the potassium ferricyanide solution was observed and analyzed. The results showed that the difference between the oxidation peak and the reduction peak potential of the activated electrode was smaller than that of the unactivated screen printing gold electrode, and the peak current became larger. In order to improve the sensitivity of heavy metals in soil, and to meet the requirements of quantitative and rapid determination, this study has observed and analyzed the silk screen printing gold electrode, bismuth modified screen printing gold electrode, Nafion (0.1%) modified screen printing gold electrode and bismuth /Nafion modified screen printing in order to improve the sensitivity of soil heavy metals. (2) The cyclic voltammetric scanning curve of the gold electrode in the potassium ferricyanide solution shows that the electrochemical performance of the modified electrode is enhanced, and the electrochemical performance of the gold electrode modified by the bismuth /Nafion modified screen is obviously enhanced, and the voltage difference between the oxidation peak and the reduction peak is the least, and the peak current is the peak current. (3) (3) in order to obtain the optimal parameters of the experiment, this study uses the differential pulse anodic stripping method and the bismuth /Nafion modified screen printing gold electrode to measure a certain concentration of standard copper solution. Based on the basis of previous research, according to the measured heavy metal copper content, the parameters of the experiment are set by the control variable method. The optimum deposition time is 360s, the deposition potential -0.7 V, the stationary time 10s, the dissolution potential 0.6V, the cleaning potential 0.8 V, the cleaning time 30 s, the electrolyte HAc-NaAc solution PH=2, the bismuth solution concentration 6000 ug/L, the Naf ion solution volume, and the standard curve of the copper concentration current are plotted, and the linear regression equation is the linear phase relation. In order to realize the measurement of heavy metal copper in the actual soil sample, the number of soil samples was measured by 0.9926. (4). First, the actual soil sample was dissolved by wet method, and the filter was formed into a corresponding soil solution. Then, the content of heavy metal copper in the actual soil samples was measured by the optimal parameter combined with the standard curve map. Finally, the content of heavy metal copper in soil was compared with the content of heavy metal copper in the same soil measured by the international standard atomic spectrophotometer. It was found that the results of the two tests are basically the same. It shows that the electrochemical detection method has good accuracy, strong anti interference ability, fast analysis speed and low cost. No pollution, suitable for the detection of heavy metals in the soil.
【学位授予单位】：山西农业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：S151.93

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