| With the rapid development of chemical industry,a large number of harmful substances into the water,and through various ways into the field of human life,among which phenolic substances are a very typical representative.Because of many phenolic substances have reproductive toxicity,carcinogenicity and difficult natural degradation,high-efficiency detection is helpful to ensure the health of residents,and it is of great practical significance.At present,large-scale instrument is the main method for the detection of phenolic substances,but its cost is high,and it is impossible to realize on-line and in-situ detection.Therefore,electrochemical method shows its superiority.The composite material with good conductivity and strong catalytic effect is usually used as the reinforcing coating in electrochemical methods,and the electrode is modified to enhance its performance,for example,to improve the detection sensitivity and so on.In this paper,three kinds of graphene matrix composites were constructed to detect different phenols.The main contents of the study are as follows:(1)Study on bisphenol A electrochemical sensor based on graphene/iron trioxide compositeGraphene/ferric trioxide composite was prepared by hydrothermal method and modified on the surface of electrode by drop coating.The graphene/ferric trioxide electrode was prepared and applied to the determination of bisphenol A in aqueous solution.The results show that the electrode modified by composite has better catalytic effect on electrochemical oxidation because of its enhanced conductivity.When the detection conditions are optimized,the performance of the sensor is tested by differential pulse voltammetry.The minimum detection limit of the sensor is 0.033 ?M(S/N=3),and the response current is linearly related to the concentration in the range of 0.1 ?mol/L.The sensor is applied to the detection of actual domestic water and bottled mineral water,and the recovery rate is 93.2% to 104.6%,which can meet the detection requirements.(2)4-nitrophenol electrochemical sensor based on sulfur-doped graphene/copper compositesSulfur-doped graphene and copper nanoparticles were synthesized by hydrothermal method respectively.The sulfur-doped graphene/copper modified electrode was prepared by uniform coating of sulfur-doped graphene and copper nanoparticles on glassy carbon electrode.Natural drying was used for the detection of 4-nitrophenol.The experimental data show that the electrical and catalytic properties of the modified electrode are enhanced.When the concentration range of 4-nitrophenol is 0.02 ?M,the response current is linear and the detection limit is 6.67 nM(S/N=3).The test results show that the sensor can be used to detect the river water and tap water in Qingdao,and the recovery is 92.55 % to 103.25 %.(3)Research of phenol electrochemical sensor based on N-doped graphene/ platinum/zinc oxide compositePlatinum/zinc oxide and nitrogen-doped graphene were prepared by hydrothermal method.The electrode was mixed uniformly and modified to the working electrode,and the nitrogen-doped graphene/platinum/zinc oxide modified electrode was prepared.The modified electrode was used to detect phenol in the solution.According to the experimental results,the electrochemical catalytic performance of the modified electrode was improved and the peak current value was increased.After optimizing the experimental conditions,the dispersion ratio,dropping amount,pH,sweep rate,enrichment time and enrichment potential were selected.The detection limit of phenol was 0.833 ?M(S/N=3)by chronoamperometric method.The linear response range of the response peak current to phenol concentration is 2.5-35 ?M.The standard recovery of tap water and bottled mineral water in our school is 93.67 % to 106.40 %,which proves that it can meet the test requirements. |
PDF Full Text Request