Research On Electrochemical Sensing Technology Of Heavy Metals Based On Ion Selective Electrode

With the rapid development of China’s industry,the problem of heavy metal pollution in water is becoming increasingly prominent.Different from other water pollution,heavy metal pollution in water has the characteristics of strong toxicity,enrichment and persistence,which makes it very difficult to control heavy metal pollution once it occurs.Therefore,the development of accurate and efficient heavy metal detection methods has far-reaching significance.At present,there are many mature heavy metal ion detection methods,but most of them are based on the laboratory.Although the measurement results are more accurate,the detection steps are often long and complex,and the technical requirements for operators are very high,which can not meet the needs of rapid detection.On the contrary,electrochemical analysis,as an important branch of heavy metal detection,its sensor has the characteristics of simple operation,low cost and rapid detection.In particular,the heavy metal electrochemical sensor based on ion selective electrode can realize the rapid detection of target detection,and has broad application prospects.However,in the detection process,it is vulnerable to the influence of temperature and solution p H,which is an urgent problem to be solved.In view of this,this thesis studies the electrochemical sensing technology of heavy metals based on ion selective electrode,mainly including the following contents:(1)The working principle of heavy metal ion electrochemical sensing system,the creation principle of self calibration model to reduce external interference and the design of corresponding system hardware and software are described.The electrode module and self calibration module are introduced in Chapter 3 and Chapter 4.(2)In the electrode module,pet is selected as the substrate,and the three electrode system electrode is made by screen printing technology.Polyvinyl alcohol(PVA)hydrogel was prepared by physical crosslinking method and modified on the surface of working electrode.Through the performance test,it is found that the obtained electrode has good reversibility,electron mass transfer characteristics and copper ion selectivity.(3)In view of the problem that it is easy to be affected by solution temperature T and p H in the detection of heavy metal ion concentration,the general law between working electrode response potential E-solution p H-solution temperature T-copper ion concentration C is explored,and a multivariate self calibration model including independent variables p H and t is established to reduce the interference caused by p H and t to the detection of heavy metal ion concentration.(4)The stability,anti-interference and accuracy of the final heavy metal ion electrochemical sensing system were tested.The relative standard deviation of the same solution is 1.41%,indicating that the stability of the system is good.In the case of interference ions,the relative error of Cu(Ⅱ)concentration is 3.90% when Pb(Ⅱ)and Cu(Ⅱ)coexist,and 6.10% when Cr(Ⅲ)and Cu(Ⅱ)coexist,indicating that the system has good anti ion interference.The system accuracy is tested under single heavy metal component(Cu(Ⅱ))and different conditions(T,p H change).The maximum relative error absolute value is 2.05%and the minimum is 0.32%,indicating that the system accuracy is good.