Synthesis Of Functional Materials And Their Electrochemical Determination Of Copper Ions

Copper ions can get and gather in human bodies through many ways like air, water and food. When copper ions reach a certain level in a body, it will get diseases, and affect terribly human health. Therefore, it is of great significance to determinate the concentration of copper ions. Metal-organic frameworks(MOFs) based on γ-cyclodextrin and composites of graphene oxide/1-pyrene butyric acid/ L-cysteine were prepared, and used to modify electrodes for the electrochemical detection of copper, which fabricated simple, fast, high sensitivity, and high selectivity of novel electrochemical sensors. The main contents are as follows:(1) The MOFs were synthesized with potassium and γ-cyclodextrin by self-assembly method at room temperature, and characterized by X-ray diffraction, IR spectra, and transmission electron microscope. The electrochemical behavior of copper(Ⅱ) was investigated on a glassy carbon electrode modified with K+-CD-MOFs by cyclic voltammetry and differential pulse voltammetry, and the various experimental factors were optimized including kinds of buffers, pH values and scan rates. Under the conditions of pH 5.0 acetate buffer, and the scan range of-0.4~0.4 V, the peak currents varied linearly with concentration of copper(Ⅱ) over the range of 1.0~91.7 mg/L, and the regression equation was-I(μA)= 1.18 c(mg/L) + 5.09(r= 0.9940), with the detection limit(S/N= 3) of 0.018 mg/L. The results indicated that this original material exhibited good electrochemical activities. The effects of other co-existing cations including Ca2+, Zn2+, Mg2+, Pb2+, Cd2+ and Hg2+ were also studied on K+-CD-MOFs modified glassy carbon electrode, which showed the peak current cannot be interfered significantly except for Hg2+. The electrochemical method displayed a short detection time, great sensitivity, reproducibility, stability and certain anti-ions interference ability.(2) The composites of graphene oxide/1-pyrene butyric acid/L-cysteine were prepared by ultrasonic-assisted chemical method, and characterized by Raman spectrum, IR spectra and electrochemical impedance spectroscopy. Glassy carbon electrodes were modified with graphene oxide/1-pyrene butyric acid/ L-cysteine composites to construct electrochemical sensor, which was used to investigate the electrochemical behavior of copper on the electrodes by cyclic voltammetry, differential pulse voltammetry and differential pulse anodic stripping voltammetry. Under the conditions of pH 4.0 Britton-Robinson buffer solution, the peak currents varied linearly with concentration of copper(Ⅱ) over the range of 0.13~7.40 mg/L. The regression equation was-I(μA)= 1.26 c(mg/L)+ 1.31(r= 0.9904), and the detection limit(S/N= 3) was 0.024 mg/L. The results indicated that the composite material exhibited good electrochemical activities and the electrochemical method displayed great sensitivity and veracity.