Establish Of Sono-Fenton-Like Processes And Investigation Of The Catalytic Performances

In recent years,water pollution endangers human health seriously.Conventional Fenton process have lots of limitations,such as high operation costs,small optimal pH range,producing amount of iron sludge and difficult to recycle the homogeneous catalyst,etc.Based on this,a heterogeneous sono-Fenton system with Rhodamine B?Rh B?as the target pollutant was established by using functional and structuralintegrated Iron foam as a catalyst or a catalyst supporter to investigate its degradation efficiency and mechanism as a pretreatment process of organic wastewater.Firstly,the sono-Fenton process based on Iron foam catalyst exhibited an obvious synergetic effect and significantly improved the removal efficiency of Rh B.The best enhanced effect could be obtained when the process treated by probe ultrasonic generator with impulsing mode.In addition,the ultrasonic power and the H₂O₂ dosage presented the positive correlation with the removal efficiency of Rh B in some extent while the initial temperature and pH showed the opposite effect.As a result,the degree of removal efficiency of 92.45% have achieved under conditions of acoustic power of 300 W,acoustic frequency of 20 k Hz,pH value of 3,initial dye concentration of 5mg·L^-1,H₂O₂ concentration of 0.5m M and treated for 1min,whereas the catalyst blocked by iron sludge in the afterward treatment.In order to overcome this drawback of iron foam catalyst,various organic and inorganic complexing agents have been tried out to replace the H₂O₂ in this process.Although some of them can broaden the application range of pH,the removal efficiency is far less than that of H₂O₂.In contrast,the bimetallic foam manifested the most optimal on decolorize the Rh B with reducing produce iron sludge.Consequently,the bimetallic foam became the one of best ways to broaden the pH range for the sonoFenton process.Secondly,the Iron-Nickel foam bimetallic catalyst has been fabricated via impregnation method.Importantly,the US/INF/H₂O₂ process achieved the highest pseudo-first-order rate constant of 70.88×10^-3·s^-1,which is 1.77 times higher than that of US/IF/H₂O₂ process.Moreover,the removal efficiency of US/INF/H₂O₂ process under initial pH of 3,4,5 were all higher than that of US/IF/H₂O₂ process,which strongly proved that such a system has broaden the pH range efficaciously.Thirdly,TiO_2-Iron-Nickel foam sono-photo catalyst has been fabricated via impregnation method.Besides,TiO_2-Iron foam,TiO_2-Nickel foam have been synthesized as well to have comparison study with TiO_2-Iron-Nickel foam,which showed that the latter one should be the best choice to use.Additionally,the UV-vis DRS analysis and the comparative trial of dark were all revealed that the TiO_2-INF catalyst have attained visible-light catalysis activity.Furthermore,the US/TiO_2-INF/H₂O₂ process achieved the highest pseudo-first-order rate constant of 1.87×10^-2·s^-1 under initial pH of 4,which is 3.40 times higher than that of US/INF/H₂O₂ process,which confirmed that the usage of TiO_2-INF catalyst not only enhanced the energy efficiency but also further broadened the pH range.Then the mechanism analysis demonstrated that the ultrasound facilitated the release and regenerate of Fe²⁺,and promoted the decompose and produce of H₂O₂ at the same time.Hence the ultrasound accelerated the Fenton reaction unit,which is beneficial to the degradation of organic pollutants.What is more,the introduction of nickel act as slow release agent of Fe²⁺,and the Ni and TiO₂ also could motivate the reduction of Fe³⁺,which expedited the homogeneous Fenton reaction.The similarity of three processes set up by different catalysts is that the most important oxidizing active species is that the cavitation collapsed and photogenic electron activated O₂ generated O₂^-·,which could oxidative decomposing organic matter and could also promotes the reduction of Fe³⁺ to Fe²⁺.Another important oxidizing active species is ·OH,especially for the TiO_2-INF catalyst which could produce the most amount of ·OH to reach the highest degradation rate under the same reaction time.Furthermore,IF,INF,TiO_2-INF catalysts were all have reasonable stability and reusability,especially for the Ni-coated catalysts,which displayed a stronger corrosion resistance.Nontheless,the activate component still trended to be shed from the surface of catalysts by ultrasonic reaction and acid washing,which made the optimization of preparation conditions to be necessary.Eventually,the comparison study of treat different sorts of dye water in US/IF/H₂O₂,US/INF/H₂O₂,US/TiO_2-INF/H₂O₂ processes,respectively.The results depicted that they have processing efficiency differences with various nature of dyes.As a consequence,how to choose the proper sono-Fenton process to reach the most idealist treatment efficiency in different influent of wastewater seems to be crucial.Above all,the INF and TiO_2-INF sono-Fenton catalyst fabricated in this study illustrated a high efficiency in dye removal,which overcame the passivation of iron foam and broaden the pH of the processing condition.Such a novel process provided a new idea for the efficient pretreatment of organic wastewater and provided theoretical basis for the regulation of the actual treatment processing.