Controlled Preparation Of Manganese Oxide Fenton Catalyst And Study Of Fenton-like Reaction Performanc

In recent years,environmental-friendly and low-toxic manganese oxides have attracted more and more attention because they can efficiently degrade organic pollutants in water by activating peroxymonosulfate（PMS）.However,there is still room for further improvement in Fenton-like reaction activity and stability of the manganese oxide catalysts.In addition,the surface active species of manganese oxide have an important impact on its catalytic performance,but the strategies for controlling the preparation of these species are still lacking.In this study,two kinds of manganese oxide catalysts were prepared via hydrothermal method by adjusting the hydrothermal temperature or the carbon chain length of alcohol additives.Their performance in catalytic degradation of dye pollutants was investigated with PMS as oxidant.The results have some reference significance for the preparation of highly active and stable manganese oxide catalysts.The research contents are as follows:（1）Between nanowire OMS-2 andγ-MnOOH that are both typical functional manganese oxides ofγ-MnOOH,the conversion can be induced facilely.The OMS-2material is found to be needle-like with smooth and flat surface.Oxygen vacancies were formed in OMS-2 due to the existence of Mn³⁺.The efficiency of OMS-2 in catalytic degradation of RhB or MB by PMS activation is significantly higher than those of commercial manganese oxides（MnO₂,Mn₂O₃,Mn₃O₄）and other analogues prepared in this work.Over a wide pH range of 1–9,the OMS-2 catalyst gave this kind of high activity.In addition,the OMS-2 catalyst can be reused for the RhB or MB degradaion for six times without significantly losing its activity.By adding radicals capturing reagents to the experimental system of OMS-2/PMS for dyes degradation to probe the active species for the reactions,we found thatSO₄^·-,OH and ¹O₂ were formed during the reactions,among which ¹O₂ is the leading one.（2）Through hydrothermal method to adjust the carbon chain length of alcohol additives,a series ofα-MnO₂ catalysts with oxygen vacancy defects are prepared.The results show that the concentration of oxygen vacancies can be controlled by adding the alcohols with different carbon chain length.The prepared catalysts exhibit morphologies of nanowire or nanorod.The prepared catalysts were used to activate PMS to degrade organic dye pollutants in water.They showed a significantly higher degradation efficiency than the commercial manganese oxides like MnO₂,Mn₂O₃,and Mn₃O₄,as well as the analogues prepared in this work.It was also found that the catalysts exhibited excellent catalytic degradation activity under acidic conditions.The radicals capturing experiments show thatSO₄^·-is the main active apecies for the reactions catalyzed byα-MnO₂ to activate PMS.