Determination Of Organic Pollutants Based On Carbon Nanotube Composite Film Modified Electrode

Carbon nanotubes(CNTs) have special electrocatalytic effect on some organic pollutants due to the properties of excellent adsorption capability, great specific surface and good electronic conductivity. In this thesis, MWNTs purified and shortened were by ultrasonication in mixed-acid of HNO3 and H2SO4, MWNTs were dispersed in the Nafion solution and coated on the glassy carbon electrode (GCE) .Operational parameters were optimized and the electrochemical behaviors of p-cresol and m-cresol were studied by cyclic voltammetry (CV) and chronoamperometry (CA).The peak current were linearly proportional to the concentrations of p-cresol in the range from 2.0×10?7~2.0×10?4 mol/L and of m-cresol from 4.0×10?7~1.5×10?4 mol/L , with detection limits respectively of 7.0×10?8 and 1.0×10?7mol/L.Meanwhile, many metal nanoparticles have been used to catalyze the reaction of small organic molecules and enhance the reaction efficiency. As CNTs are promising ideal supporting material, then platinum particles dispersed on MWNTs/GCE will catalyse greatly the reaction of some organic molecules. In the article, platinum particles were electrodeposited on MWNTs/GCE by CV, which was denoted as Pt/MWNTs/GCE. The factors influencing the electrodeposition of the platinum particles were discussed. CV and electrochemical impedeance spectra(EIS) were employed to characterize the modified electrodes. The electrochemical behaviors of low concentration of HCHO and CH3OH on the modified electrode were studied.The results indicated that the electrodes modified with the composite film exhibited an obvious electrocatalytic capability. The peak current at Pt/MWNTs/GCE is 3.5 times of that at Pt/GCE. The effect of experimental conditions on peak current was studied.The peak current were linearly proportional to the concentration of HCHO in the range 0.2~10.0μg/mL, with a detection limit of 0.1μg/mL. Furthermore, the different methods for HCHO determination were compared. On the other hand, satisfactory results were obtained by using composite-film-modified electrode to determine the concentration of formaldehyde in simulated waste water.Moreover, in the 0.1mol/L NaOH solution, composite-film-modified electrode also exhibited an excellent elecrocatalytic capability for methanol, the peak current at Pt/MWNTs/GCE is 4 times of that at Pt/GCE, and the elecrocatalytic oxidation mechanism of low concentration methanol was discussed. The peak current was linearly proportional to the concentration of methanol in the range of 2.0×10?6~1.0×10?3mol/L, with a detection limit of 1.0×10?6 mol/L. The stability and repeatability of the composite-film-modified electrode were satisfying.