The Development Of Heavy Metal Ions Based On Bismuth Film Modified Sensor

In recent years, with the rapid development of electrochemistry, especially the development of electrode materials plays an important role for the development of electrochemical sensors, and the polymer film, bismuth film and carbon nanotubes have been considered kinds of ideal modified electrode with little pollution, good stability.The preparation, characterization and application of several material sensors have been mainly studied in this paper. The glassy carbon electrode was the substrate electrode. The main preparation method was e lectrochemical polymerization, plating/potential cycling method and dripping. Three kinds of modified electrodes had been made, which are Bi/L–Tyr/MWCNTs/GC electrode, Bi/L–Tyr/Nafion/GC electrode and Bi/L–Cys/MWCNTs/GC modified electrode respectively.The p reparation mechanism of bismuth/polymer sensors and the optimal conditions of the determination for heavy metal ions Cd2+ and Pb2+ by square wave stripping voltammetry have been carried on systemic research, Specific mainly work was carried out as follows:(1) Based on the special property of the functional group monomer Tyr, the mechanism for the film formation of Bi/L–Tyr/MWCNTs/GC electrode and the electrochemical response of Cd2+ and Pb2+ had been studied by plating/cyclic voltammetry, AC impedance method, environmental scanning electron microscopy technology, in addition, the current response of heavy metal ions was enhanced by the enrichment of Bismuth and meanwhile could be detected online. The optimal preparation conditions of Bi/L–Tyr/MWCNTs/GC electrode were explored and the detection sensitivity were also improved in the experiment, the linear equations of Cd2+and Pb2+ are: ?i(?A)=14.65 c(?mol·L-(16))–0.54, r=0.9992 and ? i(?A)=10.45 c(?mol·L-(16))+4.54, r=0.9990;The linear ranges for both are 0.0100 ?mol·L-(16)~ 14 ?mol·L-(16), the minimum detection limit is 3.10 nmol·L-(16)for Cd2+and Pb2+, the magnitude is much lower than the current reports and can be applied to the real water samples;(2) The Bi/L–Tyr/Nafion/GC electrode was prepared by plating/cyclic voltammetry. The mechanism for the film formation of and the morphology changes of Bi/L–Tyr/Nafion electrode had been characterized by cyclic voltammetry,AC impedance method and environmental scanning electron microscopy technology, the mechanism of membrane formation and surface morphology were also discussed; the factors that influence the detection mechanism and current response had been studied, the linear range, response time, the minimum detection limits were also determined, the experimental results indicated that, the current response for Cd2+ and Pb2+ performed very well detected by Bi/L–Tyr/Nafion/GC electrode, the current response has a good linear relation with ionic concentration when the detection ranges for Cd2+ and Pb2+ are 0.0345~18 ?mol·L-(16)and 0.0135~18 ?mol·L-(16) respectively. The linear equations were ?i(?A)=6.38 c(?mol·L-(16))–0.42,r=0.9958 and ?i(?A)=5.17 c(?mol·L-(16))+4.73, r=0.9943;The minimum detection limit is 4.15nmol·L-(16)for Pb2+ and can be applied to the real water samples.(3) The Bi/L–C ysteine/GC electrode was prepared by plating/cyclic voltammetry. The mechanism for the film formation of C ysteine and the morphology changes of electrode had been characterized by cyclic voltammetry, AC impedance method and environmental scanning electron microscopy technology, the mechanism of polymerization and the surface morphology of poly–cysteine were discussed, the factors that influence the detection mechanism and current response had been studied, the linear range, response time, the minimum detection limits were also determined, the experimental results indicated that, the current response for Cd2+ and Pb2+ performed very well detected by Bi/L–C ysteine/GC electrode, the linear equations were ?i(?A)=4.80 c(?mol·L-(16))+11.20, r=0.9965 and ?i(?A)=4.15 c(?mol·L-(16))+7.12, r=0.9985 respectively and the current response has a good linear relation with ionic concentration when the detection ranges for Cd2+and Pb2+ are 0.03 ?mol·L-(16)~ 14 ?mol·L-(16), the minimum detection limit is 16.7 ?mol·L-(16)for Cd2+and Pb2+ and can be also applied to the real water samples.