Preparation Of MIL-125-derived Materials And Their Photocatalytic Degradation Of Antibiotics

In recent years,the use of antibiotics has become more and more common.Residual components that have not been absorbed by organisms and antibiotic wastewater that have not been treated will enter the ecological environment via biological metabolism and drainage systems.Although these antibiotics are only in trace amounts in the environment,the hidden dangers caused should not be underestimated.At present,the common treatment methods(such as adsorption,filtration,etc.)can't eliminate antibiotic pollution fundamentally,and only the degradation of antibiotics can completely eliminate the threat of antibiotics.Photocatalytic degradation,as a green environmental pollution treatment technology,can treat organic pollutants without secondary pollution and consume no other energy.As the first material used in photocatalysis,TiO₂ has been widely concerned for many years due to its low cost,low toxicity and good photocatalytic performance.However,its wide band gap and the fact that it can only react under ultraviolet light also severely limits its application prospect.In view of this,we aimed to prepare a photocatalyst with visible light responsiveness and high activity,and chose MIL-125 with a mature preparation process as the raw material to prepare a carbon-doped TiO₂ catalyst(C-TiO₂).The characterization results proved that C-Ti O2 coexists in two crystal phases:anatase phase and rutile phase,which has good crystallinity and uniform carbon doping distribution.Photodegradation experiments show that C-TiO₂ can achieve a 65.2%removal efficiency for 40 mg/L tetracycline.In order to further improve the photocatalytic performance of the material,a better performance CeO_x@C-TiO₂ composite material was prepared by impregnating Ce(NO₃)₃,and the removal rate of 40 mg/L tetracycline by 10%CeO_x@C-TiO₂ reached83.5%.The characterizations show that CeO_x@C-TiO₂ inherits the morphological characteristics of C-TiO₂,and as the content of CeO_x increases,the growth of each crystal phase is inhibited,the grain size gradually decreases,and the specific surface area gradually increases.In addition,an electrochemical workstation was used to conduct a systematic photoelectric performance study on CeO_x@C-TiO₂ composite materials,and the characterization results confirmed that 10%CeO_x@C-TiO₂ has good visible light absorption capacity,low electron-hole recombination rate and photocurrent intensity several times that of C-TiO₂.The fitting peak of its XPS Ce 3d narrow scan spectra indicated that Ce elements in the material coexist in+3 and+4oxidation states,proving the redox performance of Ce.Various characterizations and experimental results show that the type II heterojunction is the photocatalytic mechanism of 10%CeO_x@C-TiO₂.