Design And Test Of A Heavy Metal Detection System In Aqueous Environment

With the rapid development of modern industry and agriculture,people’s living standards are increasingly improved,but various environmental pollution problems have become more and more serious,including water pollution,soil pollution,air pollution,and noise pollution.Among them,heavy metal pollution in water and soil has become one of the most serious problems threatening human health due to its persistence,bioaccumulation,and extensiveness.Therefore,there is an urgent need to develop a rapid,efficient,and low-cost heavy metal detection technology to help people realize the rapid detection of heavy metals.Compared with traditional heavy metal detection technologies,electrochemical sensors have the advantages of short response time,simple instrument operation,low detection cost,simultaneous detection of multiple heavy metal ions,easy miniaturization,etc.,and have promising applications in the field of detection and analysis.This research work consists of the following three parts:(1)A disposable electrochemical sensor for lead ion detection based on conductive polypyrrole.The screen-printed electrode and the flow channel system were designed,prepared,and tested using Solid Works software to construct a flow channel detection system based on the screen-printed electrode,and the flow channel system was simulated hydrodynamically using Fluent software.The simulation results show that the liquid can cover the sensor electrode reaction area well at a flow rate of 2 ml/8 min,and the liquid in the flow channel reaches the equilibrium state within a certain time to meet the actual testing requirements.By combining a screen-printed electrode with in situ polymerized phytide-functionalized polypyrrole,a disposable electrochemical sensor(PA-PPy@SPCE)was created.The PA-PPy@SPCE electrochemical sensor has good stability,reproducibility,and anti-interference performance,and it achieved satisfactory recovery(> 93%)for the detection of Pb2+ in aqueous solution in the 10~600 n M range,with a detection limit as low as 0.43 n M(S/N = 3).The sensor has good application prospects in actual sample detection.In addition,the rapid preparation strategy of PA-PPy nanocomposites by in situ polymerization on SPCE can provide a reference for the large-scale preparation of disposable electrochemical sensors.(2)Conductive polyaniline-based electrochemical sensor for simultaneous detection of lead and cadmium.An electrochemical sensor(GA/L-Cys/PANI@GCE)for the simultaneous detection of Pb2+ and Cd2+ was constructed by the rapid preparation of conductive polyaniline nanoparticles using a total solution method and the covalent immobilization of cysteine(L-Cys)with good heavy metal complexation onto polyaniline nanofibers using a bifunctional reagent glutaraldehyde(GA).The linear range of detection was from 30 to 800 n M.The detection limits of this sensor for Pb2+ and Cd2+ are 10.5 n M and 11.6 n M(S/N = 3),respectively.The GA/L-Cys/PANI@GCE electrochemical sensor shows good stability,reproducibility,and anti-interference performance for the simultaneous detection of Pb2+ and Cd2+ and good recoveries(≥ 90%)in actual water samples,indicating that the sensor has the ability for practical application.(3)An electrochemical sensor for simultaneous detection of lead and cadmium based on nitrogen-doped molybdenum disulfide/multi-walled carbon nanotubes.A simple and rapid ultrasonic mixing method was used to prepare nanocomposites composed of cysteine,multi-walled carbon nanotubes and nitrogen-doped molybdenum disulfide(L-Cys/MWCNTs/N-Mo S2)for the construction of an L-Cys/MWCNTs/N-Mo S2@GCE electrochemical sensor for the simultaneous detection of Pb2+ and Cd2+.Using a portable electrochemical workstation and a smartphone APP,the rapid and effective detection of Pb2+(1~1000 n M)and Cd2+(30~1000 n M)was achieved by wireless Bluetooth technology,with the detection limits as low as 0.67 n M and 5.3 n M(S/N = 3),respectively.Moreover,the L-Cys/MWCNTs/N-Mo S2@GCE electrochemical sensor has good stability,reproducibility and anti-interference performance in the simultaneous detection of Pb2+ and Cd2+.In addition,good recoveries(> 90%)were obtained in the detection of both laboratory tap water and Zhengzhou Xiliu Lake water samples,indicating that the sensor has a certain practical application capability and provides a promising strategy for the simultaneous,in-situ and sensitive detection of heavy metal ions in the aqueous environment.