Research On Preparation Of Novel Oxide Chemically Modified Electrode And Their Detection Performance Of Heavy Metal Ions

Heavy metal ions are persistent and bioaccumulative in water,which seriously threatens human health.Therefore,it is very important to effectively monitor the concentration of heavy metal ions in water.Commonly used laboratory analysis methods have high detection accuracy and good sensitivity,but it is difficult to meet the needs of rapid on-site detection and real-time distributed online analysis.The chemically modified electrode is a hot spot in the field of electroanalytical chemistry and electrochemical sensors,and has the application prospect of realizing online real-time monitoring of heavy metal ions.As a chemically modified electrode functional material,colloidal oxide nanomaterials have many dangling bonds on the surface,are easy to adsorb heavy metal ions,and they can be uniformly dispersed in organic solvents,have the advantages of film formation at room temperature and good cycle stability.In this paper,the gold electrode is modified with the characteristics of high surface activity and solution processability of colloidal oxide nanocrystalline materials,and chemically modified electrodes for the detection of lead and mercury ions in water are prepared respectively.Furthermore,the dual-channel test was used to verify the feasibility of simultaneous detection of multi-component ions in complex water environment.Based on the first-principle calculation,the thesis selects WO₃ and SnO₂ as the modified materials,and calculates the adsorption energy of metal ions at different sites,and the analysis believes that WO₃ and SnO₂ have adsorption sensitivity to lead and mercury ions,respectively.Then,WO₃ colloidal nanocrystals and SnO₂ colloidal nanowires were synthesized by solvent thermal method and modified on three screen printed planar electrodes by room temperature spin coating and drop coating.Chemically modified electrodes based on WO₃ colloidal nanocrystals and SnO₂ colloidal nanowires were prepared respectively.Among them,the WO₃ chemically modified electrode has a good detection effect on lead ions.Under optimized experimental conditions,the anode stripping voltammetry was used to measure the linear response of lead ions in the concentration range of 10^-9～10^-5 M.The calculated detection limit is 9.18×10^-10 M.The SnO₂ chemically modified electrode has a good detection effect on mercury ions.Under optimized experimental conditions,the anode stripping voltammetry was used to measure the linear response of mercury ions in the concentration range of 10^-9～10^-4 M.The detection limit is3.56×10^-10 M.The thesis further uses two kinds of oxide chemically modified electrodes to form a double channel to detect and analyze the mixed solution of two heavy metal ions.By constructing the detection database of 8 kinds of mixed solutions of lead and mercury,the detection reliability of two kinds of heavy metal ions in the mixed solution is improved,which lays a foundation for the detection of heavy metal ions in complex water environment using chemically modified electrode array.