Simultaneous Determination Of Cd(?) And Pb(?) Based On Bismuth Oxycarbide Modified Electrodes

Heavy metals ions,such as Cd(?)and Pb(?),are hypertoxic even at very low concentration.Due to their non-degradable property,heavy metals can accumulate in ecosystem by food chain.They would inactivate proteins,denature various enzymes in the human body and ultimately threat human health.Facing the increasingly rigorous situation of heavy metal pollution in China,monitoring of water quality is very important.it is especially important to develop a fast and simple method in situ to operate detection.Herein,a bismuth oxycarbide was synthesized by solvothermal method.Then the surface morphology,main constituent elements,element existence state and crystal structure of the material were characterized.The glassy carbon electrode was modified by the bismuth oxycarbide,and a differential pulse anodic stripping voltammetry method suitable for the glassy carbon electrode was selected.The conditions for ion detection of the modified electrode,including deposition potential,deposition time and solution pH,were optimized.The two ions Cd(?)and Pb(?)were detected separately under the optimal experimental conditions,and the relationship between the peak current value of the stripping voltammetry curve and the ion concentration was studied.The detection limits for lead ions and cadmium ions were 4.24 ?g/L and 3.97 ?g/L,respectively.The linear detection ranges of these two ions both are 10~50 ?g/L.These detection limits are both lower than 5 ?g/L for cadmium ions and 10 ?g/L for lead ions national standards.The stability,selectivity and reproducibility of the modified electrode were also studied,and good results were obtained.This method was also applied to the actual water sample detection,and obtained a satisfactory result.In order to make this method easier to detect in the actual water sample,the bismuth oxycarbide was modified on screen-printed electrodes which are low cost and easy to industrialize.The experimental conditions for the detection of Cd(?)and Pb(?)were also optimized,and the square wave anodic stripping voltammetry which is more suitable for screen-printed electrodes was selected.The standard curves of peak current values and cadmium ion and lead ion concentrations were studied under the optimal experimental conditions.The linear relationship between the peak current values obtained at different potentials and the corresponding ion concentrations when two ions were simultaneously present were also established.The detection limit of Cd(?)for the screen-printed electrode with bismuth oxycarbide modification was 3.98 ?g/L,and the detection limit for Pb(?)was 2.39 ?g/L with the linear range was 10~50 ?g/L and 5~50 ?g/L,respectively.Compared the detection limit and the linear range,the screen-printed electrode is more suitable to apply in this method than the glassy carbon electrode.At the same time,the experimental results showed that the screen-printed electrode has excellent stability,selectivity and repeatability.The actual collected Songhua River water sample was detected by screen-printed electrode and nearly the same values were obtained with smaller concentration,which proved that the screen printed electrode has great potential for actual water sample detection.