Study On Catalytic Degradation Of Methylene Blue By Polyacrylonitrile Membrane

Nowadays,toxic organic dyes and their effluents have become one of the main sources of water pollution because of the greater demand in industry.Because of the high stability against light,temperature,chemicals,and microbial,all the dyes were difficult to remove using traditional wastewater treatment.Conventional biological wastewater treatment is usually ineffective in treating dyes because they are biorefractory and toxic to microorganisms.Some physicochemical technologies,such as adsorption,congulation,and membrane separation,have been used for the removal of various toxic pollutants,but these processes merely transfer pollutants from one medium to another,requiring further treatment.Fenton oxidation can destruct the dyes into carbon dioxide,water and other harmless small molecules.However,in the classical homogeneous Fenton oxidation process,the pH of operation must be strictly controlled around pH=3,the catalyst can not be recovered and utilized,and a large amount of sludge required further treatment.Therefore,Fenton reagent,CNTs and PAN are prepared a membrane in this study,and the Fenton reagent and CNTs are loaded on the PAN membrane.The membrane can rapid enrichment and degradation of the dyes,and easy to recovery of Fenton reagent and CNTs,but also avoid secondary pollution caused by wastewater treatment process.Three kinds of composite membranes?Fe₃O₄/CNTs/PAN,?-Fe₂O₃/CNTs/PAN and Cu₂O/CNTs/PAN?were prepared and characterized by XRD and FTIR.We mainly studied the three kinds of membranes'catalytic performance of oxidative degradation azo dye methylene blue?MB?in the presence of hydrogen peroxide?H₂O₂?.The effects of temperature,content of catalyst,amount of H₂O₂,dosage of composite membrane,initial concentration of methylene blue,pH and other factors on the catalytic efficiency were investigated,respectively.The mechanisms of H₂O₂catalytic decomposition by the Cu₂O/CNTs/PAN membranes were preliminarily discussed and the recycling performance of them were also investigated.The specific research contents and results are listed as follows:?1?The three kinds of membranes all can effectively catalyze the degradation of methylene blue in the presence of H₂O₂.Increasing the temperature can increase the increase the catalytic efficiency,but the sensitivity of the three kinds of membranes to the temperature is different.The Cu₂O/CNTs/PAN-F,?-Fe₂O₃/CNTs/PAN-F,Fe₃O₄/CNTs/PAN-F show the best catalytic effect at 60?,70?,80?respectively.In addition,increasing the catalyst content,the amount of H₂O₂ and the dosage of composite membrane,decrease the initial concentration of methylene blue can also improve the effect of catalytic degradation and catalytic rate of the three kinds of membranes to MB.?2?The effect of pH on the catalytic effect of three composite membranes was investigated.It was found that under the condition of pH 3,Fe₃O₄/CNTs/PAN and Fe₂O₃/CNTs/PAN films have the best catalytic effect on MB,and as pH is improving,the effect of Fe₃O₄/CNTs/PAN and Fe₂O₃/CNTs/PAN membranes on the degradation of MB gradually decreases.However,Cu₂O/CNTs/PAN membrane has good catalytic effect on MB in both acidic and alkaline environments.?3?By adding active capture agent IPA and Me,the mechanisms of H₂O₂catalytic decomposition by Cu₂O/CNTs/PAN films were preliminaryly discussed.?4?By evaluating the reuse performance of Fe₃O₄/CNTs/PAN,?-Fe₂O₃/CNTs/PAN and Cu₂O/CNTs/PAN films we find out that the cycling performance of the three membranes is Cu₂O/CNTs/PAN>?-Fe₂O₃/CNTs/PAN>Fe₃O₄/CNTs/PAN.