Performance And Mechanism Of Immobilized MOFs Derivative Fenton-like Catalytic Degradation Of Sulfonamide Antibiotics

In recent years,the use of antibiotics has been increasing day by day,and antibiotics are distributed everywhere through the water cycle.Long-term exposure of microorganisms in antibiotic-containing water environments lead to the drug resistance,resistance genes and resistant bacteria which seriously endanger public health safety.Therefore,the removal of antibiotics from water bodies is crucial.Due to the poor biochemical properties of antibiotics,conventional wastewater treatment processes cannot achieve their effective removal.Advanced oxidation processes（AOPs）are widely used in the field of water pollution purification because of their high treatment efficiency,wide range of application and mild reaction conditions.Fenton-like oxidation is one of the most widely studied and applied AOPs,which can generate strong oxidizing radicals and non-radicals and be used to degrade antibiotics.In recent years,although the research in this area has been fruitful,most common catalysts are powder materials,which are easy to lose and difficult to separate during operation,limiting the practical application of catalysts.Immobilezed catalysts are not only easy to recycle,but also easy to build the required equipment.However,most of the reported immobilezed catalysts are single-component catalysts,which have low catalytic activity.In this paper,metal-organic frameworks（MOFs）were used as self-sacrificing templates to construct immobilezed catalysts with heterogeneous interfaces by using aerogel and copper foam active substrates,and the rich pore structure and large specific surface area of MOFs derivatives were used to promote mass transfer and increase the active sites to enhance the performance.The Fenton-like catalytic performance and mechanism of the immobilezed catalysts were investigated using sulfonamide antibiotics as the target.The effects of water quality parameters and environmental factors on the degradation performance of antibiotics were investigated,and a fixed-bed reactor was constructed and evaluated for the treatment effect and stability of sulfonamide antibiotics during long-time continuous operation,and the results of the study provided theoretical references for the practical application of the catalyst.The details of the study are as follows:1.A series of FeS₂@TiO₂ composites（FT-x）were prepared by sulfidation treatment using disc-shaped MIL-125（Ti）as the precursor.The performance of FT-x photo-Fenton degradation of sulfonamide antibiotics was investigated under LED UV irradiation conditions.The results showed that FT-1 had the best photo-Fenton degradation performance with complete degradation of sulfamethoxazole（SMX）within 10 min,and the coexisting inorganic anions had little effect on the photo-Fenton performance of FT-1.The excellent degradation performance of FT-1 was attributed to the regeneration of Fe²⁺by photogenerated electrons and reduced sulfur species.In addition,the TiO₂ shell in the core-shell structure of FT-1 effectively protects the FeS₂ core,allowing the Fe OOH generated during the reaction of FeS₂ to be effectively preserved,which can be converted to FeS₂ again by secondary sulfidation,avoiding iron loss while achieving regeneration of the photocatalyst.The catalytic mechanism of FT-1photo-Fenton system was proposed by electrochemical analysis,active material capture experiment,XPS analysis and ESR test.Finally,FT-1 was solidly loaded using aerogel,and the results showed that it has good cycling performance and can be used for continuous treatment of SMX solution,which has some practical application potential.2.To improve the stability and catalytic performance of the immobilezed catalysts,ZIF-L（Co）was immobilized on copper foam（CF）substrate,and the immobilezed catalyst Co S_x-CuS_x/CF was prepared by sulfidation treatment.This not only increases the stability of the catalyst on the substrate but also forms a dense heterogeneous interface.This dense heterogeneous interface promoted a strong synergy between Co S_x and CuS_x,which in turn enhanced the performance of activated peroxynitrite（PMS）for antibiotic degradation.97%or more SMX degradation was achieved within 10 min with Co S_x-CuS_x/CF.The catalytic mechanism for the catalytic degradation of SMX by Co S_x-CuS_x/CF-activated PMS was proposed by active substance capture experiments,XPS and ESR.The possible degradation pathways of SMX were analyzed by liquid chromatography-mass spectrometry（LC-MS）coupling technique,and the toxicity of the intermediates was evaluated.A fixed-bed reactor was designed and fabricated for long-time continuous and efficient antibiotic wastewater treatment,and it was found that the catalytic activity of Co S_x-CuS_x/CF did not decrease significantly after 64 h of continuous operation,and the treatment volume of SMX simulated solutionwas as high as 372.6 t/kg.3.CoO_x-CuO_x/CF was prepared by converting ZIF-L（Co）solidly loaded on copper foam CF into metal oxides using high temperature calcination method,and the formation of dense heterogeneous interface between CoO_x and CuO_x was promoted by the migration of active substrate during calcination.The TOC removal rate was as high as 93.5%.And it has good anti-interference ability to common ions and natural organic matter in water,and still maintains good catalytic activity in the actual simulated wastewater.The catalytic mechanism of the CoO_x-CuO_x/CF-PMS system was proposed by active substance capture experiments,XPS and ESR.In addition,the biotoxicity of the CoO_x-CuO_x/CF-PMS system in the degradation of SMX was evaluated using Microcystis aeruginosa as the target microorganism.Finally,CoO_x-CuO_x/CF was applied to a fixed-bed reactor,and its degradation performance of various antibiotics did not decrease significantly after 128 h and 88 h of treatment of single SMX solution and mixed antibiotic solution with the treatment volume up to 533.3 t/kg and 366.7 t/kg.