Fabrication Of NH₂-MIL-101（Fe） Metal-organic Framework And Its Photocatalytic Performance For Degrading Antibiotics

As an indispensable medicine,antibiotics are widely used in daily lives,but following the substantial discharge of various wastewater,which result in severe drug residues.There is an urgent need to tackle drug residues.Classical treatment technology includes physical method（adsorption,precipitation methods,etc.）,biological treatment（biofilm treatment,aerobic/anaerobic biodegradation）,chemical technique.Among the chemical techniques,photocatalytic oxidation,driven by solar energy,have triggered considerable attention due to its economic and environmental-friendly properties.Some drawbacks of typical photocatalysts（Ti O₂,Zn O et al.）such as narrow light absorption range,low carries utilization rate severely limit their applications,so it enforces the fabrication of novel photocatalytic materials.Metal organic frameworks（MOFs）have ordered porous structure constructed from organic ligands and metal ions,and have been adopted in numerous fields such as environmental remediation,sensing,drug delivery owning to its large surface area,tunable porous structure,and high chemical stability.In addition to single photocatalyst,increasing composites exhibited better photocatalytic ability than pure components.The tight interfacial action or internal electric field inside the composites can hinder carriers recombination and promote electron transfer,which benefit the enhancement of photocatalytic performance.NH₂-MIL-101（Fe）is a typical kind of Fe-based MOFs,possessing uniform pore size,high stability,and strong visible light absorption capacity.In this work,NH₂-MIL-101（Fe）was fabricated using a classic method and tested by FTIR,XRD XPS to characterize surface morphology,elemental composition and chemical valence states etc.The optical properties and band structure of NH₂-MIL-101（Fe）was estimated through UV-vis DRS,Tauc,VB-XPS.The photocatalytic ability was evaluated to degrade levofloxacin hydrochloride（LEV）under visible light.The results showed that 30 mg NH₂-MIL-101（Fe）degraded up to 90%LEV（20mg/l）under visible light within 10 h.With the purpose of improving photocatalytic performance,a series of novel composites MTx（x=0.20,033,0.50,0.66）of semiconductor Ti O₂and NH₂-MIL-101（Fe）was designed and synthesized with a facial one-step solvothermal method.It is found that MT0.50（Fe:Ti=1:1）exhibited highest removal rate towards tetracycline hydrochloride（TC）,doxycycline hydrochloride（DC）,and levofloxacin hydrochloride（LEV）,specially reaching91.52%,80.11%,88.13%within 6 h respectively,all of which were better than the pure NH₂-MIL-101（Fe）and Ti O₂.The photocatalytic mechanism study showed that·OH acted as the main active species in the degradation process,the S-scheme heterostructure between NH₂-MIL-101（Fe）and Ti O₂inhibited the recombination of photo generated holes-electron pairs,further enhanced the photocatalytic efficiency.