A Study On The Performance Of MgO In Catalytic Ozonation For The Degradation Of Bisphenol A And Synthesis Of Anisaldehyde

This paper firstly reviews the application of ozone in water treatment on the basis of China's water resources and conventional water treatment technology.Ozone is often used in water treatment technology because of its strong oxidizing and disinfecting properties.In addition,due to the selectivity of ozone oxidative power,ozonation is also often used in synthesis of some chemicals.Owing to the defect of individual ozonation and the requirement of application,MgO catalytic ozonation is proposed.This thesis is divided into two parts:MgO/GF catalyzes the ozonation of bisphenol A;the solid base MgO catalyzes the ozonation of anethole to synthesize anisaldehyde.The MgO/GF catalyst was prepared by the equal volume impregnation method using graphite felt?GF?as the support.The performance of MgO/GF catalyst in ozonation of bisphenol A was investigated.When the initial pH of the solution was7.0,results showed that the removal percentage of BPA by MgO/GF catalytic ozonation could reach 88.2 in 9 min,which was 46.1%higher than that of ozonation alone.The initial pH of the solution had important effect on the degradation of bisphenol A.The addition of MgO/GF catalyst could effectively increase or mitigate the pH of the solution,thus improving the efficiency of ozonation.Experiments at different pH values showed that the MgO/GF catalyst could improve the efficiency of ozonation of bisphenol A by 32%to 46%.The mechanism study indicated that hydroxyl radicals played an important role in MgO/GF catalylic ozonation of bisphenol.The hydroxyl groups on the surface of the MgO/GF catalyst could decompose ozone to form hydroxyl radicals.Also,the basic sites on the surface of the MgO/GF catalyst could enhance or buffer the pH of the solution during the reaction,thus increasing the amount of hydroxyl radicals generation.When the MgO/GF catalyst was consectively repeated by five times,the catalyst still had good catalytic activity,indicating that the prepared MgO/GF catalyst is highly stable in this process.The results of gas chromatography-mass spectrometry?GC-MS?and high performance liquid chromatography?HPLC?revealed that the intermediates of MgO/GF catalytic ozonation degradation of bisphenol A mainly include p-benzoquinone,p-diphenol,4-isopropylphenol,4-isopropenylphenol,maleic acid,and acetic acid.The solid base MgO was prepared by thermal decomposition,and its performance in ozonation of anethole to anisaldehydr was studied.Compared with the traditional ozonation method,MgO/GF/O₃ could not only simplify the reaction process,but also effectively increase the yield of anisaldehyde.In this study,when 0.2g of MgO catalyst was added to a 15%water/ethanol solution,the maximum yield of anisaldehyde by ozonation was 83.6%in 150 min.Analysis showed that the added water can combine with carbonyl oxide to produce hydroxy peroxide,then directly produce aldehyde or ketone.In addition,the addition of water can enhance the density of surface hydroxyl group of MgO,thus enhancing the efficiency of ozonation.