The Detection Of Heavy Metal Copper In Soil Based On Differential Pulse Anodic Stripping Voltammetry

Not only the heavy metal pollute the soil, water and atmospheric environment, but also pollute the livestock products, aquatic organisms and crops and so on. So,in the environment, food, medicine, pesticide residue aspects, the detection and analysis of the heavy metals has been one of the topics of concern and research.Based on the traditional heavy metal detection methods have some problems, such as large expensive equipment, complex experimental procedures, and the need to have experience in the operation of the operator, this research tries to use the differential pulse anodic stripping voltammetry method of the electrochemical analysis method and the screen printing gold electrode which was modified by the liquid modified screen to detect the heavy metals copper in soil, the specific work are as follows:(1) In order to improve the electrochemical characteristics of the screen printing electrode surface, we activate the original gold electrod in the dilute sulfuric acid solution by cyclic voltammetry method, then observe and analyze the cyclic voltammetry scanning curve in the potassium ferricyanide solution. It is concluded that compared to the non activated screen printed gold electrode, the activated screen printed gold electrode's the difference of oxidation peak and potential peak becomes smaller, the current peak increases, those phenomena indicate that the electrochemical performance of activated screen printed gold electrode has been enhanced.(2) In order to improve the measurement sensitivity of heavy metals in soil and adapt the requirement of quantitative, rapid determination, we choose the following screen printed gold electrodes to work, the screen printed gold electrode modified by nothing, the screen printed gold electrode modified by bismuth, the screen printed gold electrode modified by Nafion(0.1%), the screen printed gold electrode modified by bismuth and Nafion, then respectively scan them in potassium ferricyanide solution by cyclic voltammetry method, Observe and analyze above cyclic voltammetry scanning image, we found that compared to the non modified gold electrode, the performance of the screen printed gold electrodes modified by modified liquid all developed, especially the electrochemical property of screen printed gold electrodeelectrode modified by bismuth and Nafion has dramatic development, its difference of oxidation peak and potential peak is the smallest, the current peak is the largest.(3) In order to obtain the optimal parameters of the experiment, we use the differential pulse anodic stripping voltammetry method with the screen printed gold electrodes modified by bismuth and Nation to measure the concentration of copper solution. Based on the basis of previous studies,we according to the content of heavy metal copper size have been measured and the control variables method, respectively set their parameters and obtain the following optimal parameters:optimum deposition time 360s, deposition potential-0.7v, static time 10s, dissolve out potential 0.6, cleaning potential 0.8V, cleaning time 30s, electrolyte HAc-NaAc solution PH=2, bismuth concentration 6000ug/L, Nafion solution volume 4ul, then draw the standard curve of copper concentration to current, its linear regression equation is Y= 6.54833+ 0.00505 x and the linear correlation coefficient is greater than 0.9926.(4) In order to realize the measurement of actual samples of heavy metals copper in soil, firstly we dispose the actual soil samples by wet digestion method, then filter and configure to the corresponding soil solution; Secondly we use the optimal parameter, the standard curve and the differential pulse anodic stripping voltammetry method to measure the content of heavy metal copper in actual soil samples, finally we compared to the measurement in the same actual soil samples using the international standard method by atomic spectrophotometer. We found that the two test results are basically same, so the electrochemical detection method has a good accuracy, strong anti-interference ability, high analysis speed, low cost, no pollution to the environment, and it is suitable for the detection of heavy metals in the soil.