| Now the global water pollution is serious,causing worldwide attention.With the improvement of science,industrial and agricultural productivity,many organic materials gradually joined the production process.At the same time,there are many organic pollutants were discharged into the natural water.They are numerous and most of them are extremely difficult to degrade.Among them,nitrobenzene as a stable,toxic,not easy biochemical degradating pollutant,is a great threat to human society and ecological security.In order to effectively remove nitrobenzene-containing wastewater,nitrobenzene was degraded by heterogeneous Fenton system this experiment.Compared with the traditional homogeneous Fenton system,heterogeneous Fenton system has many advantages such as a wide range of pH,the metal elements not easy to lose,no follow-up sludge and catalyst can be recycled and so on.The purpose of this experiment is making a stable,removing the nitrobenzene efficient,being repeatedly used solid catalyst and determining the best reaction conditions for multi-phase Fenton system.At the same time,exploring the intermediates of reaction to facilitate the subsequent treatment of contaminated water has practical significance for the application of this technology to the actual sewage treatment process.In this experiment,CuO/Al2O3 catalysts were prepared by isovolumetric impregnation,co-precipitation,and deposition-precipitation methods respectively,and was characterized by N2 physisorption,scanning electron microscope and X-ray diffraction.At the same time,the catalyst and H2O2 form a multi-phase Fenton system to removal nitrobenzene.Combined with the removal rate and characterization results,choosing the best performance of the catalyst.Through the research and analysis,the best preparation method of CuO/Al2O3 catalyst is deposition-precipitation method.The catalyst was prepared by deposition-precipitation method.By controlling different catalyst preparation conditions,a plurality of catalyst samples were produced.The optimum preparation conditions of the catalyst were studied by combining the characterization results with the results of nitrobenzene degradation.As a result,the loading of CuO was 5%,the calcining temperature of CuO was 400?,the calcining time of CuO was 3 h,and the calcining temperature of Al2O3 was 400?.Under the best preparation conditions,the nitrobenzene removal rate of the catalyst was 84.73%.Using nitrobenzene as the target pollutant,a multi-phase Fenton system which was formed by the catalyst that was prepared under the best preparation conditions and H2O 2 was used to degrade it.In this reaction,different reaction factors were studied by change them respectively.The results showed that the initial pH of the solution was 6,the dosage of the catalyst was 500 mg · L-1,the dosage of H2O2 was 25 mmol · L-1 and the initial concentration of nitrobenzene was 10 mg · L-1,the removal rate of nitrobenzene reaching 84.73%within 180 min.Using GC/MS,the intermediate products at different reaction time points during the reaction were detected and the degradation pathway was presumed.The results showed that the main degradation pathway was that nitrobenzene generated aniline,phenol and amino organic compounds in the system,and then further ring-opened to degrade most of the intermediate products to generate water and carbon dioxide.A small portion of the intermediate products finally formed organic matter with ester-group and other small molecules,improving the biodegradability of pollutants.After 180 minutes of reaction,after 180min,the amount of dissolved copper in the catalyst was 0.031mmol · L-1.The catalyst was stability.And The catalyst still had high catalytic performance after being reused for eight times. |
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