Electrochemical Sensor Based On Activated Bismuth-film Electrodes For The Detection Of Heavy Metals In Water

Heavy metal ion contaminants are highly toxic in humans,animal and plant tissues,non-biodegradable,and bioaccumulate,which constitutes major environmental problems.Cadmium ions and lead ions are particularly toxic to humans which can cause damage to organs and blood and are particularly important for environmental pollution,therefore it is essential for the detection of heavy metals.At present,conventional heavy metal ion detection technology cannot meet the requirements of portable,easy to use,fast and inexpensive analysis,so people are looking for a new detection technology to solve the above problems.Electrochemical sensors have the advantages of low cost,high sensitivity,fast performance and good portability,so it has attracted much attention in the monitoring of heavy metal ions.The bismuth-film electrodes has been widely used to replace the mercury membrane electrode for Stripping voltammetry analysis of heavy metal ions due to its excellent environmental friendliness and electrochemical properties.Based on the active bismuth membrane electrode,combined with special electrochemical methods,an electrochemical sensor for detecting heavy metals in water is established in this paper.(1)In this paper,different electrochemical sensors were prepared for the detection of heavy metal ions(Cd2+and Pb2+),and the physical and chemical properties of different electrodes were characterized.Characterization and analysis of surface morphology and element content of different electrodes by scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS),the cyclic voltammetry CV,electrochemical impedance EIS and square wave anodic stripping voltammetry SWV are used to characterize conductivity of different electrodes.The deposited metal is calculated by potentiostatic deposition and the above test results are verified to determine the optimal electrode for the quantitative detection of subsequent heavy metal ions(Cd2+and Pb2+).(2)A simple,rapid and green electrochemical biosensor for the detection of heavy metal ions(Cd2+and Pb2+)based on activated bismuth membrane electrodes was established.The sensor is based on the principle that the dissolution current generated by heavy metal ions(Cd2+and Pb2+)oxidation is related to the concentration of heavy metal ions(Cd2+and Pb2+)in the sample,measuring heavy metal ions(Cd2+and Pb2+)at a low concentration of μg/L on activated bismuth-film electrodes(activated BFE)by square wave anodic stripping voltammetry(SWASV).The electrode was initially modified by electrochemical method,and then improved by electrodeposition of bismuth-film,which thereby enhances the sensitivity to trace target heavy metal ions(Cd2+and Pb2+).In order to apply this voltammetric sensor to water samples containing low concentrations of Cd(Ⅱ)and Pb(Ⅱ),the experimental parameters for the electrode preparation and detection of Cd(Ⅱ)were studied.In the selected conditions,the detection limit of Cd(Ⅱ)and Pb(Ⅱ)were 1 μg/L and 2.5μg/L respectively under preconcentration conditions of 10 minutes.