Degradation Of Methylene Blue Dye Wastewater By Cobalt Ferrate Composites In Electro-Fenton System

The discharge situation of industrial dye wastewater is an increasingly serious ecological hazard,and many industries,such as textiles,leather,printing,plastics and cosmetics,discharge organic dye wastewater into the environment during production,posing a serious risk to both the environment and human health.Currently,various methods have been proposed for the treatment of organic dye wastewater,such as biological,physical and chemical treatment methods.However,conventional water treatment technologies are inefficient in treating many toxic and biodegradable organic pollutants and often fail to meet the increasingly stringent environmental discharge requirements.As a result,electrochemical technologies have received significant attention in treating wastewater pollution problems.Among them,Fenton chemistry-based electrochemical advanced oxidation processes have significant advantages in the removal of persistent organic pollutants,and the processes have the advantages of high efficiency,versatility,adaptability and environmental compatibility.So far,Electro-Fenton technology has emerged as a relatively effective option for wastewater treatment.Unlike the conventional Fenton reaction in which the hydrogen peroxide（H₂O₂）concentration gradually decreases with the increase of the reaction time after intermittent chemical dosing,the Electro-Fenton process generates H₂O₂ in situ,which can overcome the major drawbacks of its traditional approach,including the potential hazards of storing and transporting concentrated H₂O₂ solutions.In this paper,both the use of cathode materials and the degradation process of methylene blue dye wastewater and its influencing factors were explored based on the Electro-Fenton system.Firstly,catalytically active electrode materials Co Fe₂O₄/Mo S₂and Co Fe₂O₄@PPy were prepared as the cathode（working electrode）of the Electro-Fenton system to accelerate the Electro-Fenton reaction and improve the reaction efficiency by promoting the decomposition of H₂O₂ to produce hydroxyl radicals（·OH）.In addition,the cathodic Electro-Fenton process maintains the continuous supply of H₂O₂by promoting the electric regeneration of ferrous ions(Fe²⁺),thus achieving a continuous and stable degradation process.In addition,a series of characterizations of the prepared electrode materials,including infrared spectroscopy,ultraviolet spectroscopy,X-ray diffraction,X-ray photoelectron spectroscopy,scanning electron microscopy,and transmission electron microscopy,were carried out,the results all showing the successful synthesis of the materials.Furthermore,the electrochemical properties of the materials were also tested,such as cyclic voltammetry and electrochemical impedance spectroscopy.The results show that the materials have good electrochemical properties,high electrical conductivity,which is conducive to the smooth and stable process of the Electro-Fenton reaction.In this paper,the optimal reaction conditions for the degradation of methylene blue dye wastewater by Electro-Fenton method were explored.Experimental results showed that the Electro-Fenton system had the best degradation effect on methylene blue dye wastewater at p H=3,electrode spacing of 1.5 cm,current density of 12m A/cm~2,and carbon felt as substrate,which could achieve nearly 70%removal rate in30 min and almost complete removal in 90 min.In addition,the reaction mechanism of the Electro-Fenton system was also investigated by free radical quenching experiments in this paper,and the results showed that·OH plays a crucial role in the whole Electro-Fenton degradation system.In order to verify the reusability of the system,the cathode material was tested for several cycles in this study,and the results proved that the synthesized cobalt-iron-acid composite has good cycle stability.