The Study On The Detection Of Heavy Metal Ions(Pb²⁺ And Cd²⁺)in Water By Electrochemical Voltammetry Technology

In recent years,the rapid development of industry,the rapid economic growth,and the continuous improvement of people’s quality of life.However,people’s living environment has been repeatedly destroyed.Water and humans have a close relationship.Therefore,the rapid and effective analysis of heavy metal ions in the water environment becomes particularly important.Electrochemical detection has attracted much attention because of its low cost,high speed,and easy operation.Therefore,in this paper,the detection of lead and cadmium ions in water environment using carbon paste electrode and modified carbon paste electrode was studied electrochemically.The main contents include:（1）The self-made carbon paste electrode was used as working electrode.The influence of electrolyte parameters,solution pH,potential application mode,deposition potential and deposition time on the detection of heavy metal ions(Pb²⁺and Cd²⁺)in the solution was investigated to obtain the best process parameters.pH2.0 sodium chloride solution as electrolyte.The scan range was-1.3 V to-0.2 V.The deposition potential and time were-1.0V and 420 s,respectively.The amplitude and frequency were 0.045 and 40 Hz,respectively.Under this condition,the carbon paste electrode can realize highly sensitive quantitative analysis of heavy metal ions(Pb²⁺and Cd²⁺)in the water in the range of 200μg¹ mg.The detection sensitivity for Pb²⁺and Cd²⁺is 1.13μAmg^-1Land 9.19μAmg^-1L.（2）Nano-conductive carbon black was used as a modifier to modify the surface of the carbon paste electrode.The influences of the electrolyte composition,solution pH,potential application mode,deposition potential and deposition time on the detection of heavy metal ions(Pb²⁺and Cd²⁺)were investigated.The optimum process parameters are as follows:pH2.0 potassium chloride solution as electrolyte.The scanning range is-1.1 V to 0.2 V.The deposition potential and time are-0.9 V and 420 s,respectively.The amplitude and frequency are 0.045 and 50 Hz,respectively.Under this condition,the carbon paste electrode can realize highly sensitive quantitative analysis of heavy metal ions Pb²⁺and Cd²⁺)in the water in the range of 200μg¹ mg.The detection sensitivity for Pb²⁺and Cd²⁺is 1.88μAmg^-1L and 1.98μAmg^-1L.（3）The interior of the carbon paste electrode was modified with a carbon nitride powder as a modifier,and the heavy metal ions(Pb²⁺and Cd²⁺)in the water were detected by square wave voltammetry.The effects of different calcined carbonitrides,doping amount,electrolyte composition,solution pH,potential application methods,deposition potential and deposition time on the detection of heavy metal ions(Pb²⁺and Cd²⁺)were studied to obtain the best process parameters.That is,pH 2.0 sodium chloride solution as electrolyte.The doping amount of carbon nitride was 0.09 g,the scan range was-1.3 V to-0.2 V,and the deposition potential and time were-1.0 V and 420 s,respectively.The amplitude and frequency are 0.045and 55 Hz,respectively.Under this condition,the carbon paste electrode can realize highly sensitive quantitative analysis of heavy metal ions(Pb²⁺and Cd²⁺)in the water in the range of200μg¹ mg.The detection sensitivity for Pb²⁺and Cd²⁺is 1.01μAmg^-1L and 1.32μAmg^-1L.（4）Theβ-cyclodextrin was used as an internal modification material to modify the carbon paste electrode,and the optimal doping amount was determined by changing the doping amount.Aβ-cyclodextrin modified carbon paste electrode was prepared to examine the electrolyte composition and solution.The influence of solution pH,potential application mode,deposition potential,deposition time,and other factors on the detection of heavy metal ions(Pb²⁺and Cd²⁺)was optimized to obtain the optimal process parameters:pH 2.0 sodium chloride solution as electrolyte,andβ-cyclodextrin The doping amount was 0.4g,the scan range was-1.3 V to-0.5 V,the deposition potential and time were-1.0 V and 420 s,respectively,and the amplitude and frequency were 0.045 and 45 Hz,respectively.Under this condition,the carbon paste electrode can realize highly sensitive quantitative analysis of heavy metal ions(Pb²⁺and Cd²⁺)in the water in the range of 200μg¹ mg.The detection sensitivity for Pb²⁺and Cd²⁺is 1.45μAmg^-1L and 1.04μAmg^-1L.Through the study of this experiment,we modified the carbon paste electrode to improve the sensitivity of detection of Pb²⁺and Cd²⁺,and achived detection of lower concentrations of heavy metal ions,providing research direction for the subsequent electrochemical detection.