Design Of Heavy Metal Ion Concentration Detector Based On Electrochemistry

Heavy metal pollutants have the characteristics of high toxicity,non-degradation and strong bioenrichment.They are easy to migrate along the food chain and eventually enter the human body,which seriously endangers human health.The sources of heavy metal pollution are mostly the illegal discharge of factory wastes.Once pollutants enter the water body and migrate along with them,they are easy to cause diffusive pollution and cause serious consequences.At present,the heavy metal ion concentration detection equipment in the water environment has many problems,such as high price,large volume and inconvenient on-site detection.Therefore,the development of a small size,low cost,simple operation,which can meet the requirements of field application of the detection instrument has important significance and application value.In order to realize the rapid detection of heavy metal ion concentration in water,a heavy metal ion concentration detector based on electrochemical analysis technology was designed in this paper.The detector takes embedded microprocessor STM32F103RCT6 as the core,cooperated with scanning voltage circuit,potentiostatic circuit,micro-current detection unit and display module to complete the generation of scanning voltage signal and acquisition of electrochemical signal in the detection process.In order to solve the problem of wide response current range,a multi-range signal sampling circuit based on multi-channel analog switch was designed,and the software design of automatic switching range and signal sampling method was completed,so as to improve the sensitivity of the detector.In order to eliminate the influence of baseline drift,tangent recognition method was used to correct baseline and ensure the accuracy of peak current data.Differential pulse anodic stripping voltammetry based on three-electrode system and screen-printed electrode modified with bismuth film were used in the detection method.The experiment was designed to explore the influence of the four detection parameters,pH value of solution,Bi3+concentration,concentration voltage and time on the detection signal,and the best detection parameters were determined.On the premise of determining the optimum detection parameters,the standard solutions of Cd2+and Pb2+ of 0.5?mol/L,1?mol/L,2?mol/L,5?mol/L and 10?mol/L were tested respectively.The experimental results showed that the stripping peak currents of Cd2+and Pb2+ collected during the detection process had a good linear relationship with the corresponding concentration.The linear correlation coefficients of Cd2+and Pb2+ were 0.9942 and 0.9979 respectively,and the repeatability of ion detection at the same concentration was good.Compared with the results of atomic absorption spectrometry,the maximum relative error was 4.93%,which could meet the needs of heavy metal ion concentration detection in industrial field water.The heavy metal ion concentration detector designed in this paper has fast detection speed,stable performance,high accuracy and simple operation.It provides an effective technical means for timely detection and treatment of heavy metal pollution from the source.