Study On The Preparation And Performance Of Photocatalytic Degradation Of Ibuprofen In Fe-MOFs Based Composite Catalysts

Ibuprofen?IBP?,a kind of organic pollutant with high stability and potentially harmful to human health,are widespread in the water environment.Thus,they have drawn great environmental concerns.Metal-Organic Frameworks?MOFs?is a new kind of porous framework material with high specific surface area,adjustable pore size and diverse types,which has been widely used in the fields of adsorption,hydrogen storage and catalysis.In recent years,MOFs have been applied as typical semiconductor photocatalysts and have attracted much attention.Unfortunately,it is generally accepted that the fast recombination of photo-generated electron-hole pairs is still a significant challenge.Two-dimensional materials such as molybdenum disulfide and graphene have the characteristics of high conductivity and large specific surface area,which can improve the transfer of electrons.At the same time,Ag/AgCl has broadband system,plasma resonance effect and other characteristics,which can form z-type heterojunction with many semiconductors,which can not only reduce the recombination of photogenerated electron-hole pairs,but also retain outstanding redox ability.In this study,Fe-based MOFs heterojunctions are fabricated by combining Fe-based MOFs and suitable semiconductors such as 1T-MoS₂,graphene oxide?GO?and Ag/AgCl.The photocatalytic performance of those composites and the corresponding reaction kinetics are evaluated by removing IBP in the environment water.The main research content of this study is as following:1.Fe-MOFs composites 1T-MoS₂@MIL-53?Fe?,GO@MIL-88A?Fe?and Ag/AgCl@MIL-88A?Fe?were successfully prepared by a facile in-situ solvothermal approach of integrating 1T-MoS₂?GO and Ag/AgCl with typical MOFs.The crystalline phase,morphology and the specific surface area of the as-prepared composites were characterized XRD,XPS,SEM,TEM and BET.These XRD patterns illustrated that the introduction of 1T-MoS₂?GO and Ag/AgCl may change the equilibrium between organic ligands and metal ions and affect the reactants,which lead to change of lattice constitution of MOFs.BET analysis demonstrated that a typical coexistence of micropores and mesopores of those composites were emerged.Meanwhile,the specific surface area of 1T-MoS₂@MIL-53?Fe?,GO@MIL-88A?Fe?and Ag/AgCl@MIL-88A?Fe?are 337?408.9 and 138.6m² g^-1,respectively,which were 16.0,25.7 and 5.3folds than that of pure MOFs.2.The photocatalytic properties and the corresponding reaction kinetics were determined by degrading IBP under visible light irradiation.The related electrochemical analysis were measured to analysis the decisive factors for the improved photocatalytic efficiency.The optical doping content of 1T-MoS₂?GO and Ag/AgCl were 5 wt%,9 wt%and Fe:Ag=2:1,respectively,and the corresponding photo-degradation rate were 1.183,1.234 and 1.213 h^-1,which were 7.5,7.6 and 10.8fold than that of pure MOFs.Meanwhile,the optical photocatalysts were labeled as TSMF-5,M88/GO-9 and ACMA-2,respectively.Photochemical tests showed that the three composites have faster separation and migration efficiency of photoelectric carriers and stronger visible light adsorption compared with the pure MOFs.These effects are conducive to the improvement of photocatalytic efficiency,which were consistent with the analysis of corresponding photocatalytic experimental results.3.The active species trapping experiments were measured to determined the main active radicals in the three photodegradation systems,indicating that·O₂^-,h⁺and e^-were the main active radicals in the ACMA-2 system,·O₂^-,·OH and e^-played important role in the TSMF-5 and M88/GO-9 systems.The photo-degradation intermediates were identified by ion chromatography?IC?and LC-MS-MS,indicating there were HCOOH and CH₃COOH generated in the three system,5 decarboxylated metabolites of IBP in the ACMA-2 system,and 8 decarboxylated and hydroxylated metabolites of IBP in the TSMF-5 and M88/GO-9 systems.The different photo-degradation intermediates were detected,which were mainly related to the existence of different active species in different systems.Total organic carbon results showed that the mineralization rates of ibuprofen in TSMF-5,M88/GO-9 and ACMA-2 were 93%,95%and 91%,respectively.The possible photodegradation mechanisms and photodegradation pathways of ibuprofen by TSMF-5,M88/GO-9 and ACMA-2 were proposed,respectively.