The Study On Synthesis Of Oxide Containing Cobalt Electrode Materials And Applications For Heavy Metal Detection In Water

Heavy metal ions?HMIs?in water are common contaminants,which take a great threat to ecosystem and human health.Hence,it is necessary to found a fast,accurate,and can be quantitative analytic method of HMIs in water.In this paper,the synthesis technology of oxide containing cobalt was studied.Then oxide containing cobalt was modified on a glassy carbon electrode for qualitative and quantitative detection of HMIs.Square wave anodic stripping voltammetry?SWASV?was used to investigate the electrochemical response for modified electrodes detection HMIs.The main contents are as follows:?1?Co₃O₄ were prepared by a hydrothermal method.The crystal phases and micrographs of Co₃O₄ were analyzed by X-ray diffraction?XRD?and scanning electron microscopy?SEM?.The results show that Co₃O₄ sized about 5?m were blocks structure stack-up with hexagonal nanosheets.Co₃O₄ modified glassy carbon electrode?Co₃O₄-GCE?was used for determination Pb?II?by SWASV.Under optimized experimental condition,plots of peak current and the concentration of Pb?II?were linear correlation.The linear regression equation was:I??A?=7.31c??mol/L?+1.30,r²=0.997.The sensitivities and the detection limits of Co₃O₄-GCE were 7.31?A/?M and 2.24?g/L?S/N=3?,respectively.There was no effect on the detection results of Pb?II?when Cd?II?and Hg?II?in the solution.Co₃O₄-GCE has good stability and reproducibility.Recovery experiments were carried out in simulated wastewater.And the average recovery rate was 99.56%.?2?ZnCo₂O₄ were synthesized by hydrothermal method,then characterized by XRD,SEM.ZnCo₂O₄ with particle size of about 15?m were irregularly block particles.Glassy carbon electrode coated with ZnCo₂O₄ was used for determination Cu?II?through SWASV method.Electrochemical determination of Cu?II?reveal that ZnCo₂O₄-GCE showed greater response to Cu?II?,higher sensitivities of 1.51?A/?M,lower detection limit of 1.84?g/L.It will lead to the lower results of Cu???when the solution contained Cd?II?.When Pb???or Zn?II?and Cu???coexist in the solution,the results of Cu???have nearly no effect.And the stability of ZnCo₂O₄-GCE was light.Meanwhile,the results of average recovery in simulated wastewater was 101.15%.?3?Synthesis of NiCo₂O₄ via a microwave-assisted hydrothermal and characterized by the methods of SEM and XRD.Both the results from SEM and XRD manifested that NiCo₂O₄ were microspheres with rambutan-like structure,whose size were around 3?m⁵?m.There were numerous needle-like villi on the surface of NiCo₂O₄ microspheres,such special structure provided a large number of adsorption sites for HMIs.NiCo₂O₄modified glassy carbon electrode?NiCo₂O₄-GCE?detection Cd?II?,Pb?II?and Hg?II?by SWASV has an effective electrochemical response.The detection limit of Cd???,Pb???,Hg?II?were 8.23?g/L,5.78?g/L,4.61?g/L,respectively.NiCo₂O₄-GCE has good stability when simultaneous detected Cd?II?,Pb?II?,Hg?II?.Recovery experiments on Cd?II?,Pb?II?,Hg?II?showed high recovery rate.