Preparation Of Slag Particle Three-dimensional Electrode And Study On Its Efficacy In Removing Methylene Blue From Water

With the development of society and the advancement of science and technology,more and more chemical products are developed and used and discharged into the water environment,and the water environment pollution is becoming more and more serious.Among them,dye wastewater is a major source of industrial wastewater.Due to the biological toxicity of dye wastewater,it is difficult to effectively remove it by traditional water treatment processes.Electrochemical oxidation technology can quickly decompose and oxidize organic pollutants into small molecules with low toxicity or non-toxicity in water,and can even be further thoroughly converted into CO₂,H₂O and inorganic salts.Therefore,it has become a research hotspot to remove refractory organic pollutants in water.Three-dimensional electrochemical oxidation technology can make up for some of the shortcomings of traditional two-dimensional electrochemistry,such as:low degradation efficiency of organic matter,high processing energy consumption,etc.Therefore,three-dimensional electrochemical technology has attracted a lot of research in recent years.Among them,the high cost of materials for making three-dimensional particle electrodes is a major factor restricting its development.Therefore,the development of efficient and inexpensive particle electrodes will be of great significance to the practical application of three-dimensional electrochemical technology.This paper focuses on the method of"using waste to treat waste",using industrial solid waste thermal power plant slag as raw material to prepare particle electrodes,and using methylene blue?MB?as a model organic pollutant,to study the performance and mechanism of three-dimensional electrochemical system to degrade methylene blue in water.In order to further improve the catalytic ability of the particle electrode,the surface is loaded with metal,and the improvement of the catalytic ability of the new particle electrode is discussed.The specific research work carried out in this paper is as follows:A method for preparing particle electrodes using slag from a thermal power plant is proposed.By designing orthogonal experiments,the effect of preparation conditions on the catalytic degradation of methylene blue is studied.The results show that the optimal condition for preparing slag particle electrode is the material ratio:slag:clay:pore forming agent mass ratio of 6:3:1,the calcination temperature is750?,and the calcination time is 120 min.A series of characterizations is carried out on the slag particle electrode.In the three-dimensional electrochemical oxidation reaction system,under the experimental conditions of 10 V electrode voltage,0.1 mol/L electrolyte concentration and particle electrode dosage of20 g,the degradation rate of methylene blue in water can reach 78.1%,which is higher than that of pure two dimensional electrochemical system.The recycling performance of the particle electrode is tested.After the first use,the catalytic ability of the particle electrode decreased slightly.The reason for this phenomenon is that organic molecules or reaction intermediates are adsorbed on the surface of the particle electrode and the particle electrode may be worn.The experiment explores a series of factors that affect the degradation of methylene blue in the three-dimensional electrochemical oxidation system?particle electrode dosage,electrolyte concentration,voltage strength,initial pH of the solution,etc.?The results show that the removal rate of methylene blue increases with the increase of particle electrode dosage,electrolyte concentration and voltage intensity.The initial pH of the solution has a significant effect on the oxidative degradation ability of the system.The removal rate of methylene blue under acidic conditions is higher than that under alkaline conditions.In the investigation of the reaction mechanism,radical quenchers such as methanol,tert-butanol and phenol are added to conduct free radical identification experiments.The experiment found that the existence of hydroxyl radicals is the main reason for the degradation of methylene blue,and explored the location of the degradation reaction of methylene blue.After adding methanol and tert-butanol separately in the three-dimensional electrochemical oxidation system,the removal efficiency of methylene blue was reduced to a certain extent,and after adding phenol,the removal efficiency of methylene blue decreased significantly.This indicates that the hydroxyl radical is the main oxidative active material for the system to degrade methylene blue.When the current in the system passes through the slag particle electrode,the hydroxyl radical can be excited,and the degradation reaction of methylene blue mainly occurs on the surface of the particle electrode instead of the solution.The surface of the slag particle electrode was loaded with three different metals?zinc,iron,manganese?by the impregnation-calcination method.The degradation rate of methylene blue by the particle electrode after metal loading was greatly improved.Among them,the metal manganese-loaded slag particle electrode has the best performance in removing methylene blue in water,and its catalytic degradation efficiency of methylene blue is increased by about 40%compared with the original particle electrode.The conditions for loading the particle electrode with manganese were optimized.The selected experimental conditions were:dipping time 2 h,dipping solution concentration 0.5 mol/L,calcination temperature 550?,and calcination time 1h.