Study On Lewis Acid Enhanced Mesoporous Materials Catalytic Ozonation Of Refractory Pharmaceutical Pollutants

Heterogeneous catalytic ozonation technology has the advantages of complete oxidation of organic pollutants,good stability,renewable and reusable catalyst,etc.In recent years,it has become a research hotspot in the field of environment.However,at present,the mechanism of heterogeneous catalytic ozonation is only limited to theoretical speculation,lack of systematic and in-depth study.Firstly,this thesis researches the transformation of ozone under the action of catalyst and the degradation of pollutants,which reveals the mechanism of catalytic ozonation.Based on the rule of ozone transformation on the catalyst surface,the catalyst was designed,which is used to catalyze degradation of pharmaceutical pollutants in water by ozonation.Take ibuprofen for example,it mainly studies on its transformation and inhibition of the formation of bromate,a toxic by-product.At last,in order to explore immobilization of catalyst,through the fixed bed continuity experiment,shows the feasibility of its application in continuous water treatment.The primary research conclusions and consequences are as follows:1.Transform based on the ozone on the catalyst surface,Lewis acid enhanced mesoporous nanospheres Fe-Al-SiO₂were successfully designed and prepared.It was found that the catalyst had high catalytic activity and stability.The characterization results show that Fe and Al are highly dispersed on the surface of SiO₂,and Lewis acid sites on the surface of SiO₂ are greatly increased.In situ attenuated total reflection infrared spectroscopy and electron paramagnetic resonance?EPR?spectroscopy confirmed that the active atom group was produced by the decomposition of ozone on Lewis acid site of the catalyst.Besides,the mutual conversion of Fe³⁺and Fe²⁺can promote the decomposition of ozone.However,the metal elements of catalyst and Lewis acid site promote the decomposition of ozone to produce more·OH and O₂^·-radicals,which leads to the highest mineralization rate of ibuprofen.At the same time,in the water containing ibuprofen and bromine ions,catalytic ozonation of bromine containing wastewater can effectively block the formation of bromate and realize the reduction of bromate in the water containing bromate.The study is confirmed that the electronic cycle of Fe²⁺/Fe³⁺controling bromate generation by the reduction of bromate and the decomposition of HBr O,an intermediate active species in bromate formation.In the course of the experiment,we found the competition between humic acids and pollutants and it will reduced ozone catalytic effect.2.The mesoporous solid?-Cu-Ti-Al₂O₃ catalyst is successfully designed and prepared.?-Cu-Ti-Al₂O₃ has high catalytic activity and stability for ibuprofen,phenytoin,diphenhydramine and ciprofloxacin.The results show that Cu²⁺and Ti⁴⁺doped into the framework of?-Al₂O₃ form Al-O-Ti and Al-O-Cu bonds,and the presence of Ti and Cu greatly enhances the Lewis acid sites of?-Al₂O₃.For Fe,Cu,Ti and other metals,the electronic cycle of multivalent metals is conducive to the production of^·OH and^·OH radicals by ozone decomposition,and the addition of organics can promote the electronic cycle of multivalent metals,thus generating more^·OH and O₂^·-radicals.Raman and EPR spectra show that ozone decomposes simultaneously on the surface of?-Cu-Ti-Al₂O₃ to produce new directly with the organic acids adsorbed on the surface of the catalyst to make it mineralized,thus having a high mineralization rate for the drugs.At the same time,I found that competition between humic acids and pollutants.The catalyst has better adaptability to water quality,so it has a broader application prospect.3.A new catalyst Fe-Al pellet is determined,and the catalyst immobilization is further carried out in the laboratory pilot study.Application in the laboratory water distribution treatment is investigated.The removal rate of TOC is about 50%when the equipment is operated for 100 hours,and the removal rate is good after repeated use,which shows that the composite pellet is a promising ozonation catalyst.