Detection Of Heavy Metal Ions In Water By Bismuth-based Electrochemical Sensor

In recent years,the pollution of heavy metals has attracted considerable attention.Heavy metal ions will do great harm to human health because of their high toxicity,non-biodegradability and persistence,even if they are trace in food and drinking water.Among the heavy metal ions,Cd（II）and Pb（II）ions are considered to be the typical toxic metal ions in human blood and drinking water.Therefore,it is necessary to monitor the amount of Cd（II）and Pb（II）efficiently.Electrochemical analysis has the advantages of fast detection,simple operation and low cost,which is widely used in analyzing of heavy metal ions.Mercury film electrode is usually used in stripping analysis to achieve high sensitivity and repeatability,but its wide application is limited due to the toxicity of mercury.Bismuth-based material modified electrode is an ideal substitute for mercury-based electrode due to its low toxicity,insensitivity to dissolved oxygen,ability to form alloy with heavy metals and high sensitivity.In this dissertation,aiming at the problem of heavy metal pollution in the environment,electrochemical sensing platforms with excellent performance are constructed on the basis of exploring new working electrode materials,which are intended to realize the detection of heavy metal ions.BiW₉,Bi₂Se₃ nanoflowers,Binanospheres and Bi₂W₂₂ were prepared by simple methods.Scanning electron microscopy,X-ray diffraction,Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to analyze the morphology,structure and element composition of the materials.Cd（II）and Pb（II）ions were detected by square wave anodic stripping voltammetry.First,combining the advantages of Bi-based materials and polyoxometalates,BiW₉ and Bi₂W₂₂containing Bias the center atom were prepared and used as electrode materials for the detection of heavy metals Cd（II）and Pb（II）ions.BiW₉ and Bi₂W₂₂ modified glassy carbon electrodes have wide linear range and low detection limit for the detection of Cd（II）and Pb（II）.Secondly,Bi₂Se₃ nanoflowers with good morphology and dispersion were prepared without the presence of water and oxygen,which were used as electrode materials to detect Cd（II）and Pb（II）ions for the first time.Compared with Bifilm electrode,bismuth nanoparticles possess abundant active sites and high electroanalytical activity.Thus,bismuth nanospheres were used as electrode materials for the analysis of Cd（II）and Pb（II）.Electrochemical results show that bismuth nanospheres exhibit wide linear range,low detection limit and high sensitivity towards the detection of Cd（II）and Pb（II）.In addition,these bismuth based materials possess good selectivity,repeatability,reproducibility and stability for the detection of Cd（II）and Pb（II）ions,and own broad application prospects in the detection of practical water samples.