Performance And Mechanism Of Enhancing Sulfamethoxazole Degradation In Water By Ozonation Synergism With HSZSM-5

The residual antibiotics in water environment pose a potential threat to human health and environmental safety.Ozonation can effectively remove such substances.However,due to the selective oxidation of ozone with organics,ozonation has problems such as low ozone utilization rate and limited TOC removal ability.In this paper,the high-silicon ZSM-5zeolite（HSZSM-5）with coadsorption capacity for antibiotics and ozone was used to enhance ozone oxidation of sulfamethoxazole（SMX）.Then,the CeO₂@HSZSM-5 catalyst was prepared by impregnation-precipitation method for heterogeneous catalytic ozonation process to improve the removal rate of TOC.The removal efficiency and influencing factors of HSZSM-5/O₃ synergistic process on sulfamethoxazole（SMX）in water were studied.The experiment results demonstrate that the coadsorption of SMX and ozone by the HSZSM-5/O₃ synergistic process can increase the reaction rate between them and completely remove SMX in water within 15 minutes,and the ozone consumption is only 65.0%of the O₃ alone system.SMX removal rate was positively correlated with ozone concentration,p H and CO₃^2-/HCO₃^-concentration.The removal rate of TOC was only 41.3%within 30 minutes of the collaborative process.The oxidative regeneration of HSZSM-5 test results show that the regeneration effect of HSZSM-5 is positively correlated with ozone dosage,regeneration time and p H.The"adsorption-regeneration"experiment results suggest that HSZSM-5 has the best regeneration effect under the condition of p H=10,and the adsorption capacity after 5 times of recycled use is 12.8 mg/g,which is 9.1 times that of unregenerated one.TGA/DTG and XRD analyses revealed that SMX filled the sinusoidal pores of HSZSM-5 during the adsorption process.FTIR analysis confirmed that ozone restored the adsorption capacity of the HSZSM-5 pores by the"Cleaning Effect".The effect of CeO₂@HSZSM-5 heterogeneous catalytic ozonation system on TOC removal was studied.The characterization results indicate that 10 wt%CeO₂@HSZSM-5has a high specific surface area.The surface CeO₂ nanoparticles are uniform in size,and the abundant surface hydroxyl groups are the active sites of the catalyst.The ozone utilization rate and ozone degradation rate in the catalytic ozone oxidation system are 1.4times and 2.3 times that of the ozone oxidation system alone.Also,the catalytic ozonation system increases the electron transfer rate,so that more Ce⁴⁺in the oxidation process is reduced to Ce³⁺.The experimental results show that the TOC removal rate increased by53.5%compared with the ozone oxidation system alone,under the conditions of p H₀=7,ozone dosage of 6.2 mg/L,and catalyst dosage of 0.4 g/L.The TOC removal rate is positively correlated with ozone and catalyst dosage.Except for initial p H=11,the p H of the heterogeneous catalytic ozonation system dropped to 2.8-3.5 within 30 minutes,which led to the difference in the final TOC removal rate.CeO₂@HSZSM-5 reduced the removal rate of TOC by only 5.9%after repeated use for 5 times,and the physical structure and surface chemical properties did not change significantly.