Catalytic Ozonation For The Degradation Of Pharmaceutical Wastewater In Aqueous Solution By Ceria Particles

Catalytic ozonation is an important component of advanced oxidation technology, and catalysts play an important role during reaction. In this research, we successfully prepared Ce/AC catalyst and core/shell magnetic ceria catalyst. The research focused on the efficiency of the catalytic degradation of pharmaceutical wastewater by a variety of catalyst (activated carbon, Ce/AC catalyst and core/shell magnetic ceria catalyst) and the relationship between catalysts structure and the degradation efficiency. Based on ozone oxidation system which has been established, adding catalysts and we compared the degradation effects among different catalysts, and explore the performance of a variety of catalysts and the degradation pathway of pollutants. From ozonation and catalytic ozonation degradation kinetics characteristics, the contrast of the mineralization rate, the factor that influence the reaction, the ozone utilization and the reaction mechanism analysis, we discussed the synergistic effect of the various catalysts and real application value.First, APAP was selected as model pollutant and the degradation in aqueous solution by ozonation process was explored. The effects of factors that affected the reaction rate were carefully studied. Based on the intermediates detected by GC-MS, IC and HPLC, the degradation possible pathway was discussed. A kinetic reaction model of APAP degradation was deduced. This part can provide basic data to further research.Second, the degradation of APAP in aqueous solution by using ozonation integrated with activated carbon(AC) was studied. The efficiency of degradation of APAP by three processes (ozonation alone, activated carbon alone and ozonation integrated with activated carbon) was compared. The operational parameters that affected the reaction rate were carefully optimized. Based on the intermediates detected, the catalytic degradation possible pathway was discussed and the reaction mechanism was also investigated. The results showed that the TOC removal was greatly enhanced and reached55.11%at60min in AC/O3system, while the effects of ozonation alone, activated carbon alone were only20.22%and27.39%, respectively. And biodegradability was also greatly improved.Third, cerium supported on activated carbon catalyzed ozonation for p-TSA degradation was studied. The p-TSA and COD removal efficiency were compared among O3alone, AC/O3and Ce/AC/03processes. The influence of operational factors on the removal of p-TSA was carefully investigated. A possible degradation pathway of p-TSA and the reaction mechanism of ozonation catalyzed by cerium supported on activated carbon were proposed. The results showed that Ce/AC catalyst could greatly enhance the degradation of p-TSA by ozonation and Ce/AC/O3process was most efficient for COD removal. The COD removal with Ce/AC catalyst at60min could reach74.1%, while62.4%with AC catalyst,50.8%using ozone alone and only24.4%using Ce/AC alone. And the best loading amount of Ce is1wt%.Forth, we prepared unique Fe3O4@SiO2@CeO2catalyst with the structure of a Fe3O4magnetic core, a silica membrane mid-layer and CeO2outer layer. ASA was selected as model pollutant to evaluate the catalytic ozonation activity. A possible degradation pathway of ASA and the reaction mechanism of ozonation catalyzed by Fe3O4@SiO2@CeO2catalyst were proposed. The characterization techniques used to probe these catalysts were XRD, FT-IR, TEM, SEM, and EDX. In addition, stability and recyclability of the Fe3O4@SiO2@CeO2catalysts were also discussed. The results showed that TOC removal with Fe3O4@SiO2@CeO2catalyst at120min could reach44.2%, while36.5%with Fe3O4@SiO2,35.4%with Fe3O4and only34.2%with ozonation alone. According to stability and recyclability test of the Fe3O4@SiO2@CeO2catalysts, the results showed that the catalysts would be helpful in the separation and had magnetic recyclability and low metal leaching.