Study On Degradation Of PAM By Combined Cathodic Electro-Fenton And Anodic Oxidation

The wide application of water-soluble polyacrylamides (PAM) causes serious environmental pollution.In this paper, Fe3O4/graphite felt composite was used as the anode and cathode of the battery.The degradation of PAM was carried out in the single chamber reactor,we studied the degradation process of the PAM and the electrode material.We also clarified the degradation pathway of PAM and the degradation effects of PAM under different systems.The Fe3O4 / graphite felt composites were prepared by solvent evaporation and high temperature calcination. The composites were characterized by SEM, XRD and TG.The results showed that the surface of materials was Fe3O4 and the loading is 24.5%.The prepared Fe3O4/graphite felt composites were used as the anode and cathode, and combined method to degrade PAM with molecular weight of 1.5 ×107.The effects of the chemical oxygen demand (COD) and the relative viscosity of the solution were investigated.The effects of the electrochemical Fenton method, the anodic oxidation method and the combined method on the degradation of PAM were investigated. Compared with the single method, the combined method showed better performance. When the applied voltage was 2V and the initial pH was 7, the COD of the solution reduced by 45.6% and the relative viscosity decreased from 2.19 to 1.04.The degradation products of PAM were characterized by gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The results showed that the carbon backbone of PAM was shortened during the degradation process, and the side chain groups were destroyed and ether bond was formed. The resulting polymer showed good biodegradability.The degradation of PAM with molecular weight of 1.7 × 106, 6.6 × 106 and 1.1× 10-7was carried out, and the degradation mechanism was analyzed. The results showed that the hydroxyl radical ( · OH) during the electrocatalytic degradation was attack PAM main chain on the "head - head" junction, and the formation of ether bond with shorten the PAM carbon chain.