Comparative study on electrochemical degradation of 4-chlorophenol by different Pd/C gas diffusion electrodes

摘要

Pd/C catalyst used for the Pd/C gas diffusion cathodes was prepared by hydrogen reduction method and formaldehyde reduction method, and characterized by X-ray diffraction (XRD), transmission electrode microcopy (TEM), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV) techniques. The electrochemical degradation of 4-chlorophenol was investigated in the diaphragm electrolysis system, aerating firstly with hydrogen gas then with air, using three different kinds of gas diffusion cathode. The results indicated that the self-made Pd/C gas diffusion cathode can not only re-ductively dechlorinate 4-chlorophenols by aerating hydrogen gas, but also accelerate the two-electron reduction of O_2 to hydrogen peroxide (H_2O_2) by aerating air. Therefore, the removal efficiency of 4-chlorophenol by using Pd/C gas diffusion cathode is better than that of the C/PTFE gas diffusion cathode (no catalyst). The catalytic activity of Pd/C catalyst prepared by hydrogen reduction method is higher than that prepared by formaldehyde reduction method. The stability of the Pd/C gas diffusion cathodes is good. Therefore, both the removal efficiency and the dechlorination degree of 4-chlorophenol reached about 100% after 60 min, and the removal efficiency of 4-chlorophenol in terms of chemical oxygen demand (COD) in the cathodic compartment reached 87.4% after 120 min.