The Research Of Electrochemical Sensor For Heavy Metal Determination In Water

Heavy metal pollution can damage human health and destroy the ecological environment, thus more and more people pay attention to it. The concentration level of heavy metals in the environment is very low, but considering the bioaccumulation, it is very dangerous. So it is necessary to find a fast, convenient and accurate method to detect trace amounts of heavy metals. Traditional methods usually carried out in the laboratory. The procedures of sampling, transport and storage, sample processing and testing are cumbersome and time costing. Besides, the equipments are expensive. Thus, we should develop convenient, fast, accurate, on-site and real-time online measurement for heavy metal detection to be. In recent years, electrochemical sensor gets people's attention in the field of environmental monitoring and detection of heavy metals. It has many advantages, such as simple equipment, easy operation, high sensitivity, on-site test and online analysis. It is suitable for the detection of heavy metals in the environment. With the development of new materials and new electrochemical analysis methods, electrochemical sensors will play an important role in the future. This study provides two kinds of electrochemical sensors and explores their application in the detection of trace heavy metals.We fabricated a glassy carbon electrode(GCE) modified with ordered mesoporous carbon(OMC) and thiolated polyaniline(PANI) for simultaneous determination of trace Cd2+ and Pb2+ in the present of bismuth by differential pulse anodic stripping voltammetry(DPASV). The morphology and electrochemical properties of the fabricated electrode were respectively characterized by scanning electron microscopy(SEM) and electrochemical impedance spectroscopy(EIS). Experimental parameters such as PANI disposition, preconcentration potential, preconcentration time and bismuth concentration were optimized. Under optimum conditions, the fabricated electrode exhibited li near calibration curves ranged from 1 to 120 n M for Cd2+ and Pb2+. The limits of detection(LOD) were 0.26 n M for Cd2+ and 0.16 n M for Pb2+(S/N=3), respectively. Additionally, repeatability, reproducibility, interference and application were also investig ated, and the proposed electrode exhibited excellent performance. The proposed method could be extended for the development of other new sensors for heavy metal determination.We also designed an electrochemical DNA sensors used in the detection of Hg2+. Three single-strand DNA(ss DNA) chains with specific sequences were designed and used in the detection of Hg2+ through chronocoulometry based on T-Hg2+-T principle. [Ru(NH3)6]3+(Ru Hex) was used as hybridization indicator. The ss DNA was modified on the electrode surface through Au-S bond. Electrochemical detection signal was proportional to Hg2+ concentration. The results showed that the design of this DNA sensor and Hg2+ detection strategy is correct. The sensor has good anti-interference performance and can be used for seletive detection of Hg2+ in the environment.