Degradation Of PAM Under Heterogeneous Electro-fenton And Further Research

The wide application of water-soluble polyacrylamides （PAM） causes serious environmental pollution.In this paper,the PAM was preliminarily degraded by Heterogeneous Electro-Fenton method, and then the microbial degradation was carried out. This can effectively improve the degradation efficiency of PAM. We used the electrochemical, analytical chemistry and microbiological methods to explore the electrochemical degradation of PAM and the further degradation by microorganism.First, a partially hydrolyzed PAM with molecular weight of 1.5 × 10⁷ and a degree of hydrolysis of 25% was used as the substrate. We take the Heterogeneous Electro-Fenton method to degradate PAM. It found that the best working electrode was Fe3O4/GF. pH has little effect on the degradation, and we chose pH7. potentials have great effects on the degradation of PAM. The best degradation effect potential is ^-1.1v. At this potential, the ammonia nitrogen raised to 82.78 mg · L^-1, COD decreased from 508.17mg · L^-1 to 410.67 mg · L^-1,the degradation rate of PAM was 19.19%,he the contrast viscosity near 1. We deal the molecular weight of 1.75 X 106 and 6.6 X 106 PAM in the same way, the degradation results were basically as the same as those with molecular weight of 1.5×10⁷.The degradation products were characterized by gel chromatography,infrared and photoelectron spectroscopy. The chain cleavage and termination of PAM by electron-Fenton process is complex,the C-C bond of polymer chain was broken at the head-to-head linkage and carbon radicals were formed. This could liberate small molecular organic and inorganic carbon compounds . The new carbon-centered radicals formed from bond scission are extremely unstable, and will have a strong propensity to react with oxygen to afford a peroxy macromolecular radical. Peroxy radicals have strong propensity to abstract hydrogen atom available in the polymer backbone, resulting in a new carbon-centered radical and a hydro peroxide species. This macromolecular hydro peroxide end group can readily decompose to form an oxygen-centered radical and a hydroxyl radical. Hydroxyl radical abstract can further abstract hydrogen atoms, thus forming new carbon centered radicals. Combination reaction between the oxygen-centered radical and carbon-centered radical...