Study On The Performance And Mechanism Of Anodic Oxidation Of Organic Pollutants At Graphite Felt Electrode Modified By Metal Oxide

Hazardous synthetic organic pollutants in industrial wastewater are potential threats to ecosystem balance and human health.Environmentally friendly and economically viable technologies are urgently needed for the management of toxic and harmful compounds.Anodic oxidation?AO?is viewed as a clean technology to convert deleterious organic pollutants into less-toxic or non-toxic states by electron transfer reaction.Carbon and graphite are often used as electrode materials because of their low cost,stable chemical property and good conductivity.However,carbon material is easily destroyed at high voltage,and so in recent years some metal oxides have been loaded on the surface of carbon materials to improve their stability.In this work,low-voltage degradation of phenol is achieved in an anodic oxidation?AO?-assisted O₂ oxidation process with Fe₃O₄/graphite felt?GF?composite anode.Batch experiments on phenol degradation at 0.6 V achieve phenol removal in 78 h,and the total mineralization of phenol is obtained in 90 h at the first cycle.The time required for phenol removal is reduced to 48 h after three cycles of operation,meanwhile mineralization of phenol being completed in 51 h.The AO-assisted O₂ oxidation process is confirmed to adopt a non-radical pathway in which the phenol is degraded at the catalytic sites of GF under the synergy of O₂ and anodic electric field.Phenol degradation efficiency at the Fe₃O₄/GF composite anode is significantly higher than that at the GF,which is ascribed to the accelerated electron transfer by Fe₃O₄.The Fe-C and Fe-O-C bonds are identified as inherent linkages responsible for electron transfer between the Fe₃O₄ and GF.Process efficiency is able to be spontaneously enhanced in recycling operation due to the intensification of Fe-C and Fe-O-C bonds.In order to obtain composite materials with better catalytic performance,in the later experiments,we select MnO₂ to prepare MnO₂/GF composite electrode,which is used to treat 50 mg L^-1 methylene blue?MB?solution in three-electrode system.The degradation efficiency of MB solution is improved greatly.97.7%MB can be removed within 120 min,and TOC can be completely removed within 3 h.Compared with the bare GF,the degradation efficiency is greatly improved.The degradation effects of the prepared material for other dyes are also very good,and the influencing factors of the oxidation process are simply described.The results show that oxygen and anodic electric field are the necessary conditions for the degradation process,and the hydroxyl radical?·OH?produced contributes greatly to the degradation.The experiment uses GF of low cost as raw material and is operated at low voltage.The low consumption and high degradation efficiency in the degradation of pollutants show that the prepared GF electrode modified metal oxide has a great application prospect in the treatment of organic pollutants.