Preparation Of Chlorine Modified Activated Carbon Fiber Electrode For Electro-Fenton Degradation Of Orange ?

Azo dyes are widely used in the printing and dyeing industry,and their comprehensive use is also the first in comparison with other dyes.Azo dyes have stable chemical structure and therefore belonging to refractory organic pollutants,and they are easily converted into aromatic amines.Therefore,research on its degradation is the focus of dyeing wastewater treatment.Electro-Fenton has received extensive attention due to its environmental friendliness,high efficiency degradation and ease of operation.Its main principle is to combine the Fenton reaction with the electrochemical reaction and degrade pollutants by electroreduction oxidation.This method realizes the continuous regeneration of hydrogen peroxide?H₂O₂?and Fe²⁺,which can generate hydroxyl radicals?·OH?by Fenton reaction.Finally,·OH mineralize the pollutant molecules by its strong oxidizing property.The cathode material has an important influence on the generation of hydrogen peroxide in the electro-Fenton process.In this paper,activated carbon fiber and cyanuric chloride were used as raw materials to prepare chlorine modified activated carbon fiber?Cl/ACF?by high-temperature sintering method.The unique physicochemical properties of chlorine were used to modify the ACF cathode material to improve the catalytic properties of the electrode.At the same time,the physical and chemical properties of the materials were analyzed and compared by using scanning electron microscope?SEM?,specific surface area tester?BET?and X-ray photoelectron spectroscopy?XPS?.In the experiment,Cl/ACF was used as the cathode,platinum electrode was used as the anode,and azo dye acid orange II was used as the simulated wastewater?0.05mol/L Na₂SO₄ and 160mg/L Orange II?.The electrochemical characteristics and degradation effect of Cl/ACF were studied by electro-Fenton experiment.Experiments show that the Cl/ACF system has a stronger TOC removal ability than the ACF under the same conditions,and the chlorine loading can improve the treatment effect of the electro-Fenton.The effects of different experimental conditions(catalyst loading,solution pH,initial Fe²⁺concentration and current density)on the degradation of Orange II simulated wastewater were studied.The optimal reaction conditions:0.2-Cl/ACF as cathode material,initial pH of the solution was 3,the initial Fe²⁺concentration was 0.5 mmol/L,and the current density was 3 mA/cm².Under this condition,the removal efficiency of TOC by Cl/ACF system was 93%,which was about 1.33 times of the removal efficiency of ACF system?69.8%?.Electrochemical method,reagent coloring method and instrumental measurement have proved that the chlorine loading can accelerate the formation of H₂O₂ by inhibiting hydrogen production and accelerate the conversion of Fe³⁺to Fe²⁺,which is beneficial to the formation of·OH radicals and improves the degradation effect of the system.In addition,the surface reaction was confirmed by electrodeposition experiments..It was found that the Fenton degradation experiment mainly occurred on the surface of the cathode:surface electrodeposited Fe²⁺reacted with adsorbed H₂O₂ to produce·OH.Finally,the degradation intermediates of Orange II were detected by gas chromatography-mass spectrometry?GC-MS?,and the reasonable degradation pathway was presumed.