Simultaneous Detection Of Cadmium,lead And Mercury Ions Based On Carbon Materials Electrochemical Sensor

The pollution problem of heavy metal ions has always been deeply concerned,and these metal ions can play a destructive role at a very low concentration in the ecological environment and human health.Therefore,it is necessary to detect the low concentration of heavy metal ions in order to control their harm to the environment and human body.Traditional heavy metal ion detection methods（such as atomic absorption spectroscopy,etc.）have disadvantages such as high price and long detection cycle,while electrochemical sensor,whose advantages in detecting heavy metal ions are convenient and low price,can satisfy the detection conditions well.Three electrochemical sensors have been designed in this paper,based on the principle of selective adsorption for heavy metal ions biomass carbon,and its aim to improve the sensitivity,broaden the linear range and lower the limit of detection.（1）Biomass carbon attached nano-Au electrochemical sensor was prepared by one-step method at high temperature.The SEM,XRD and Elemental Analyzer have been employed to observe morphology and achieve material identification.The SWV has been utilized to simultaneously detecte Cd²⁺and Pb²⁺.Under optimal conditions,linear ranges were both 2.5～7.5μM,and calibration plots were y=3.09（±0.154）C_Cd-5.52（±0.755）and y=4.53（±0.213）C_Pb-5.15（±0.901）,respectively.The corresponding limit of detection were respectively calculated as 7.33×10^-7 M and5.97×10^-7 M（S/N=3）.The linear correlation coefficients were separately fitted as 0.999and 0.995,and the sensitivities were separately calculated as 54.2μA·μM^-1·cm^-2 and79.5μA·μM^-1·cm^-2.The sensor was applied to the detection samples in lake water and fresh cucumber,and the results showed that the recovery rates were well.（2）Biomass carbon loaded with Fe₃O₄ and ionic liquid electrochemical sensor was assembled through ultrasonic method,in which Fe₃O₄ was synthesized by hydrothermal method.The SEM,XRD and Elemental Analyzer have been employed to observe morphology and achieve material identification.The SWV has been utilized to simultaneously detecte Cd²⁺,Pb²⁺and Hg²⁺.Under optimal conditions,Linear ranges were both 2.5～20μM,and calibration plots were y=5.29（±0.134）C_Cd-12.6（±1.35）,y=7.13（±0.277）C_Pb-6.71（±3.61）and y=3.42（±0.129）C_Hg-5.34（±1.61）,respectively.The corresponding limit of detection were respectively calculated as 7.66×10^-7,1.51×10^-6and 1.41×10^-7 M（S/N=3）.The linear correlation coefficients were separately fitted as0.995,0.995 and 0.994,and the sensitivities were separately calculated as 91.2μA·μM^-1·cm^-2,123μA·μM^-1·cm^-2 and 59.0μA·μM^-1·cm^-2.The sensor was applied to the detection samples in lake water and fresh cucumber,and the results showed that the recovery rates were well.（3）The carbon paste electrode CILE was prepared by biomass carbon mixed with ionic liquid.The difference of hydrogen evolution potential between the bare glass carbon electrode and the carbon paste electrode were further researched,and results showed that the hydrogen evolution potential is-1.22 V for glassy carbon electrode and-0.84 V for carbon paste electrode,respectively.Besides,a portable electrochemical sensing device was put forward,with which Cd²⁺,Pb²⁺and Hg²⁺were simultaneously detection.Under optimal conditions,Linear range were both 0.5～6μM,and calibration plots were y=9.96（±0.266）C_Cd+0.873（±0.894）,y=17.2（±0.576）C_Pb+4.96（±2.10）and y=7.15（±0.320）C_Hg+9.33（±1.19）,respectively.The corresponding limit of detection were respectively calculated as 8.98×10^-8 M,4.99×10^-7 M and 4.99×10^-7 M（S/N=3）.The linear correlation coefficients were separately fitted as 0.995,0.995 and 0.998,and the sensitivities were separately calculated as 48.8μA·μM^-1·cm^-2、84.3μA·μM^-1·cm^-2 and 35.0μA·μM^-1·cm^-2.The sensor was applied to the detection samples in lake water and fresh cucumber,and the results showed that the recovery rates were well.