Preparation Of Salt-tolerant Catalysts And Catalytic Ozonation Of High-salt Wastewater

High salinity wastewater poses a major challenge to achieving wastewater reclamation and reuse.Traditional wastewater treatments have certain limitations when applied to such wastewater.The introduction of high-salinity wastewater into ecosystems can cause serious damage.Therefore,there is an essential and pressing need to enhance technology research for high-salinity wastewater treatment.The heterogeneous catalytic ozonation process is considered a promising technology for treating wastewater with high salt content due to its high efficiency and green.In this study,two salt-tolerant catalysts capable of masking Cl^-were prepared to solve the problem of low efficiency of catalytic ozonation for the treatment of high-salt wastewater.Meanwhile,the preparation parameters of the two catalysts were optimized and their catalytic performance in saline organic wastewater was investigated.The main findings were as follows:（1）Fe-Ce/AC catalysts were prepared by loading Fe and Ce onto activated carbon treated with 1 M dilute nitric acid.The optimal preparation parameters were:active metal loading of 1 wt%,Fe/Ce mass ratio of 1:1,and calcination temperature of 450℃.（2）Fe-Ce/Al₂O₃catalysts were prepared by loading Fe and Ce onto Al₂O₃.The optimal preparation parameters were:Fe impregnation amount of 3 wt%,Ce impregnation amount of 1 wt%and calcination temperature of 600℃.（3）The regulation for the points of zero charge(p H_pzc)of the catalyst was achieved by acid treatment and loaded metal.The activated carbon was treated with dilute nitric acid.The alumina was impregnated with a certain concentration of iron solution.By adjusting the concentration of the impregnating solution,the p H_pzcof alumina-based catalyst can be regulated between 4.42 and 8.48.The relationship between catalyst p H_pzcand solution p H is an important factor affecting the catalytic ozonation efficiency of the catalyst in Cl^-containing wastewater.（4）Fe-Ce/AC and Fe-Ce/Al₂O₃were used for catalytic ozonation of 100mg·L^-1ibuprofen（IBP）wastewater.In the solution without Cl^-,when the solution p H was close to the catalyst p H_pzc,the two catalysts exhibited the best catalytic performance with the COD removal rate of 85.67%and 83.75%,respectively.In the solution with Cl^-(5000 mg·L^-1),when the solution p H was above and close to the catalyst p H_pzc,the two catalysts exhibited the best catalytic performance with the COD removal rates of 79.83%and 85.67%,respectively.This result is caused by factors such as O₃decomposition and electrostatic repulsion on the catalyst surface.（5）The presence of Cl^-increases the O₃concentration in the solution.There are reactive oxygen species such as·OH,·O₂^-,and ¹O₂in the O₃/Fe₃-Ce₁/Al₂O₃system.In the solution without Cl^-,the largest contribution to the mineralization of organic matter is from the surface·OH and ¹O₂.In the solution with Cl^-(5000 mg·L^-1),the largest contribution to the mineralization of organic matter is from the surface·OH.The main reason for the high catalytic efficiency of the catalyst in high-salt wastewater is the absence of significant scavenging effect of Cl^-on the surface·OH.