| In recent years,with the development of advanced oxidation technology,persulfate oxidation technology has made great progress.These technologies take the sulfate radical(SO4-·)as the main project of study.Many new persulfate activation methods have been proposed,and microwave(MW)radiation is one of them.In this study,microwave radiation was used to activate potassium persulfate(PS)to degrade rhodamine B in water.According to the experimental data,the influence of microwave radiation on the persulfate oxidation system was studied.This project used intermittent microwave radiation mode innovatively,and combine microwave radiation and catalyst to show its synergistic activation effect.It had activation advantages such as fast and efficient.The effect of microwave operation mode,microwave power and running time were compared.In the consideration of energy consumption,the operation mode of high power microwave intermittent radiation was determined.This mode asked operate for 15 s and then stop for 45 s in the condition of 700 W microwave power.Other conditions affecting the reaction were analyzed too,such as potassium persulfate concentration,p H value of reaction system,rhodamine B concentration,etc.It also analyzed the influence of the catalyst to the reaction,including the type and dosage of the catalyst.Both phase transition metal ions and non homogeneous transition metal oxide took a good catalytic effect on the reaction in high temperature situation.About the concentration of rhodamine B was 100 mg/L,concentration of potassium persulfate was 3 mmol/L,without p H value adjustment and the addition of catalyst,under the condition of microwave power 700 W intermittent radiation,the rhodamine B can be completely removed in 10 min,the degradation rate of TOC was 41.9%.Through comparison between microwave radiation and conventional heating in the heating mode and pollutant removal ability,thermal effect of microwave radiation was evaluated.Compared with the traditional heating,microwave radiation had a rapid heating ability,and was not affected by the temperature of the system.The microwave energy effective utilization rate was increasing with the increased of microwave power and receptor volume.In addition,the kinetic and thermodynamic calculations of the reaction were carried out on the basis of experiments.Compared with the traditional heating,microwave radiation can reduce the activation energy significantly,which reflect its non-thermal effect.Moreover,microwave radiation can be combined with Fe3O4 to expand the advantages of non-thermal effect further.The experiment found that microwave radiation bring a high temperature environment(over 90 °C)in the reaction process,the reaction can not fit the first-order kinetic equation.It was necessary to calculate the apparent kinetics of persulfate oxidation reaction under the high temperature conditition.Through the calculation,it was determined that it was the two-order reaction,and the oxidizing agent persulfate concentration was the determinant factor of reaction.Free radical quenching experiments showed that sulfate radical was the main active species in the reaction.Through the analysis of IR spectra of the reaction groups found that microwave activated persulfate has certain mineralization ability of rhodamine B,but the reaction was not completely. |
