Study On Electrochemical Detection Of Heavy Metal Contaminants With Graphene-based Nanocomposite

The rapid development of socialist industrialization and modernization not only brought great economic benefits,but also gave great harm to the environment,especially the pollution problems of heavy metal ions in the aquatic environment is particularly prominent.These heavy metal ions are non-biodegradable and tend to accumulate in living organisms,thereby causing persistent damage to the health of animals and humans.Therefore,it is very important to find a method for detecting heavy metal ions that combines the advantages of rapidness,accuracy,and high efficiency.So far,many analytical methods have been used to detect heavy metal ions in aquatic environment.However,electrochemical analysis method is generally considered to be an effective ion detection technology by the virtue of high sensitivity,rapid,low cost,and convenient for in-stiu detection.With the development of nanotechnology,nanomaterials are widely used for the electrochemical detection of heavy metal contaminants due to their unique physical and chemical properties,such as platinum,gold,and metal oxides,but they are all obtained through complex synthesis methods and cost highly.Based on the principle of simple and economy,it is necessary to find new nano-materials with simple synthesis methods,low cost and high sensitivity and anti-interference the for detection of heavy metal ions.Combined the excellent conductivity of graphene with the excellent adsorption properties of flower-like MoS₂ and NiO nanostructured materials,two new types of sensing interface were constructed to achieve high sensitivity and anti-interference detection of heavy metal ions.The main research contents of this paper is as follows:First,the flower-like MoS₂/rGO nanocomposite was synthesized and used as electrode modification material to detect four heavy metal ions including Pb???,Cd???,Cu???and Hg???under optimal experimental conditions,which showed higher electrochemical response toward Pb???.Afterwards,the adsorption experiments were conducted,and the reasonable explanations about the electrochemical response of MoS₂/rGO nanocomposite modified electrode toward four heavy metal ions were given.Then,taking Pb???for an example,a series of interference experiments have done.We found an interesting phenomenon: Two Pb???stripping peaks can be observed in the presence of Cu???in electrolyte,while there is only one stripping peak of Pb???in the absence of Cu???,and the presence of other heavy metal ions?such as Cd???,Cu???,and Hg????has no significant effect on the sensitivity of Pb???.Finally,the accurate analysis of Pb???in wastewater samples collected from Wang Xiaoying Sewage Treatment Plant was carried out,which proved that MoS₂/rGO has a good application for electrochemical analysis for heavy metal ions in real water samples.Second,the spherical NiO/rGO nanocomposite was successfully synthesized and the modified electrode was prepared.Electrochemical analysis of four heavy metal ions,Pb???,Cd???,Cu???and Hg???were carried out by anodic stripping voltammetry.Afterwards,we conducted interference experiments and drew a conclusion that the presence of other heavy metal ions does not affect the sensitivity of NiO/rGO nanocomposite modified electrodes toward Pb???.Finally,the stability and reproducibility of the modified electrodes were tested and the good results were obtained.