Preparation Of Electrochemical Sensor Based On Carbon Nano-material And Its Application On Detection Of Heavy Metal Ions In Water

With the deepening of urban industrialization,heavy metal pollutants are becoming more and more serious to the soil,atmosphere and water environment.At present,heavy metal pollution has become one of the most harmful water pollution problems,and has brought great challenges to human survival and development.Heavy metals mainly through human pollution sources such as industrial wastewater and sewage into rivers,lakes,reservoirs and other water bodies,large and heavy metal toxicity,in the environment are difficult to metabolism,easy to enrichment in organisms,thus causing serious lasting pollution of water environment,and poison aquatic animal life.At the same time have through contaminated groundwater pollution of water,agricultural irrigation water indirect pollution of crops and so on a variety of ways to enter the human daily life,in imperceptible in serious threat to human life and health.At present,the methods of detecting heavy metals are expensive,expensive and cannot be detected in situ.Therefore,it is urgent to establish an economical,fast and green field detection of heavy metal methods.In view of this,this paper is to heavy metal lead(Pb²⁺),cadmium(Cd²⁺)as the research object,with carbon nano materials as the core material,the use of anodic stripping voltammetry,set up a kind of economic,fast,convenient and practical method of electrochemical sensor.The main works are as follows:（1）An integrative electroanalytical method was developed for detecting cadmium(Cd²⁺)and lead(Pb²⁺)ions in aqueous solution.Based on carbon nanometers graphene material,the preparation of polysulfide（nS,n=2,3,4,5）modified redoxgraphene（RGO）film,we optimized processing the nS,established detection of Pb²⁺and Cd²⁺electrochemical sensing method,at the same time.Polysulfide/graphene（RGO-4S）nanocomposites were prepared and their sensing performance as an electrochemical sensor for Cd²⁺and Pb²⁺was evaluated.The RGO-S nanocomposite was carefully characterized by scanning electron microscopy（SEM）with an energy-dispersive X-ray detector,transmission electron microscopy（TEM）,and X-ray photoelectron spectroscopy（XPS）.The as-prepared RGO-4S was incorporated into the pyrolytic graphite electrode（RGO-4S/PGE）and then used for detecting trace amount of Cd²⁺and Pb²⁺ions with differential pulse anodic sweeping voltammetry（DPASV）.Under optimal conditions,the stripping peak current of the RGO-4S/PGE is linear with heavy metal ion concentration ranging from 2.0 to 300μg L^-1 for Cd²⁺and from 1.0 to 300μg L^-1 for Pb²⁺.The limits of detection（LOD）for Cd²⁺and Pb²⁺were estimated to be about 0.67μg L^-11 and 0.17μg L^-1,respectively.The prepared electrochemical heavy metal-detecting electrode provides good repeatability and reproducibility with high sensitivity,making it a suitable candidate for monitoring Cd²⁺and Pb²⁺concentrations in aqueous environmental samples.（2）A simple and easy method was improved for contemporary detection of Cd²⁺and Pb²⁺ions by using 1,3,6,8-pyrene tetra sulfonic acid sodium salt functionalized carbon nanotubes nanocomposite（PyTS-CNTs）.The morphology shape and composition structure of the obtained PyTS-CNTs were described by scanning electron microscopy（SEM）,energy dispersive spectrometer（EDS）and X-ray photoelectron spectroscopy（XPS）.The results of experiments performed that the fabricated PyTS-CNTs performed developed selectivity and dispersibility for metal ions sensing due to the insertion of sulfonic acid groups.In case of Cd²⁺and Pb²⁺,the electrochemical sensing process was carried out via varying data’s such as quantity of PyTS-CNTs loaded on the pyrolytic graphite electrode（PGE）,p H of the acetate buffer solution,deposition time and deposition potential were optimized with differential pulse anodic sweeping voltammetry（DPASV）.Under optimal conditions,the stripping peak current of the PyTS-CNTs/Nafion/PGE is linear with heavy metal ion concentration ranging for Cd²⁺from 1.0 to 80μg L^-11 and for Pb²⁺from 1.0 to 100μg L^-1.The limits of detection（LOD）for Cd²⁺and Pb²⁺were estimated to be about 0.8μg L^-1 and 0.02μg L^-1,accordingly.PyTS-CNTs/Nafion/PGE can be used as a fast,simple and controllable electrochemical sensor of toxic Cd²⁺and Pb²⁺to assess the heavy metal detection’s potential from aquatic ecosystems.（3）Carbon matrix materials are considered as one of the most important electrode materials for heavy metal detection,it is desirable,but still remains challenging to improve c nitric oxide reduction graphene（NG）for roles in tracing Cd²⁺and Pb²⁺.PyTS was prepared to modify the nitric oxide reduction graphene（NG）materials An electrochemical inductor method for the detection of heavy metal Cd²⁺and Pb²⁺was established.The morphology of the prepared materials was characterized by scanning electron microscopy（SEM）,and the types and contents of the elements in the microregion were analyzed by means of EDS.The chemical composition of the material was analyzed by X-ray photoelectron spectroscopy（XPS）.Electrochemical conditions such as deposition potential,deposition time,pH of the acetate buffer solution and quantity of PyTS-NG loaded on PGE were optimized.Based on optimal conditions,the linearity curves of Cd²⁺and Pb²⁺were obtained by changing the concentration of one species while keeping the other stable,This was possible due to its unique structural feature and N content.The PyTS-NG possess excellent detection limits of 0.33μg L^-1 for Cd²⁺and 0.17μg L^-1 for Pb²⁺（S/N=3）with the deposition time 300s.Moreover,tap water were used as practical samples to evaluate the detection of Cd²⁺and Pb²⁺,respectively.The calculated recovery（95%-105%）indicated that PyTS-NG have potential as a promising material with which to monitor the concentration of Cd²⁺and Pb²⁺in practical samples.