Behavior And Mechanism Of Typical Antibiotics Removal In Aqueous Solution By MOFs And Their Derivatives With Peroxymonosulfate

Antibiotic contamination in water bodies has become a global question in the last decades.Antibiotics in the water environment have the characteristics of stable structure and poor biodegradability,which are difficult to remove by conventional water treatment.Advanced oxidation technology shows broad application prospects in wastewater treatment for the fast reaction rate,high degradation efficiency and no secondary pollution production.The core of advanced oxidation technology is the synthesis of catalysts.Metal-organic framework materials have attracted much attention because of their ultra-high porosity,adjustable pore structure,and evenly distributed active sites.However,the poor water stability and low catalytic activity limit its application in aqueous phase catalytic reactions.Therefore,in this topic,metal-organic frameworks are modified by transition metal doping,chemical modification,pyrolysis in an inert atmosphere,and immobilization with three-dimensional macroscopic supports.In addition,the removal behavior and mechanism of various antibiotics by metal organic framework materials and their derivatives have been systematically explored.The main research contents of this subject are as follows:（1）A novel cobalt doped Ui O-66（Co Ui O-66）was fabricated via a one-step solvothermal strategy.The Co Ui O-1（Zr:Co molar ratio was 1:1）exhibited the highest adsorption capacity towards tetracycline（TC）and more than 94.7%of initial TC can be removed under simulative sunlight irradiation.The adsorption capacity of Co Ui O-66 for TC was related to the dosing amount of Co Ui O-66,co-existing anions,and the initial p H value and concentration of TC solution.Pseudo-second-order and Freundlich models can describe the adsorptive process.The adsorption of TC on Co Ui O-66 was spontaneous and exothermic.The photocatalytic degradation experiments of TC exhibited the cobalt doping could improve the photo-absorption range of Ui O-66 and promoted charge separation,which were helpful to improve photocatalytic property.In addition,this study proposed a possible degradation pathway of TC.Co Ui O-66 showed towards a high removal efficiency for practical water samples（including tap water,river water and pharmaceutical wastewater）containing TC.The synthesized Co Ui O-66 in this study provided a feasible method for the removal of TC from water.（Chapter 3）（2）In view of the weak coordination between the metal center and organic ligands of metal-organic framework（MOFs）materials,the derivative materials obtained by in-situ etching strategy can greatly improve the water stability.On basis of cobalt zeolite imidazole framework（Co-ZIF）,aluminum-cobalt layered double hydroxide（Al Co-LDH）with uniform composition was prepared through an in-situ etching strategy at room temperature.Al Co-LDH exhibited excellent catalytic performance for peroxymonosulfate（PMS）activation towards TC degradation.The removal rate of TC by Al Co-LDH/PMS system could reach 92.3%within 5 minutes,and the total organic carbon（TOC）removal rate could reach49.1%within 30 minutes.In addition,the degradation rate constant based on the pseudo-first-order kinetic model of the Al Co-LDH/PMS system(0.980 min^-1)was16.6 times higher than the Co-ZIF/PMS system(0.059 min^-1).Al Co-LDH had a unique hydrotalcite-like layered structure and its large surface area and pore volume allowed TC molecules to easily diffuse and interact with the active site.The higher content of aluminum ions in Al Co-LDH catalyst facilitated the electron transfer between the lower content of cobalt ions and PMS.The formation process of Al Co-LDH and the degradation mechanism of TC were discussed.In addition,the Al Co-LDH catalyst was stable in water with almost no metal ions leaching.This study provided a novel and simple route for the synthesis of layered bimetallic hydroxide catalysts derived from MOFs with high catalytic performance and stability,which had a reference value for the application of PMS-based advanced oxidation technology to wastewater remediation.（Chapter 4）（3）In view of the difficulty of effective recovery of metal-organic framework materials used in aqueous-phase catalysis,a space-confined strategy was adopted to prepare the derived materials with magnetic properties,high catalytic ability and stability.Nitrogen-doped porous carbon encapsulated magnetic Co nanoparticles（Co@NC-800）were successfully prepared by two-step high temperature pyrolysis of cobalt-based zeolite imidazolate framework（ZIF-67）with a rhomboid dodecahedron morphology.The obtained Co@NC-800 showed good stability in catalytic degradation of TC by PMS activation.After the catalytic degradation experiment,there was no obvious cobalt ion leaching,and the used Co@NC-800could be easily recovered by magnet.Co@NC-800/PMS system can remove 90.1%of TC within 3 minutes,and 74.7%of total organic carbon（TOC）in 30 minutes.The mechanism study suggested that the space-confined strategy was beneficial for improving the catalytic ability and stability of Co@NC-800.The radicals(SO₄^·-and O₂^·-)and non-radicals（¹O₂）produced in the degradation process acted together on the degradation of TC.In addition,the Co@NC-800/PMS system also showed high removal efficiency towards various antibiotics（oxytetracycline,aureomycin and doxycycline）.Even in real water bodies（tap water,river water and pharmaceutical wastewater）,Co@NC-800/PMS system also shows excellent performance for TC removal.Co@NC-800 with magnetic property,good catalytic properties and reusability,which showed great potential application in the treatment of antibiotics-containing wastewater.（Chapter 5）（4）The preparation of macroscopic objects from metal-organic frameworks（MOFs）derived carbon-based materials is significancant to broaden their industrial application.Based on iron-doped zinc zeolite imidazole framework（Fe-ZIF-L）,a three-dimensional（3D）compressible Fe-doped nitrogen carbon/aerogel（Fe@NC-800/AG）was synthesized via a freeze-drying and low-temperature calcination technique.The Fe@NC-800 powders were uniformly and tightly dispersed in the channels of 3D AG.Interestingly,the Fe@NC-800 can function as the mechanical support skeleton and provide catalytic sites to activate PMS for degrading various organic pollutants in aqueous solution.The Fe@NC-800/AG/PMS system exhibited outstanding TC degradation performance（94.3%of TC can be degraded after 60 min）and recycling ability（90%of removal efficiency can be achieved after reused for 10 times）.Moreover,the integrated multilayer filter composing of two pieces of Fe@NC-800/AG showed high TC removal efficiency（>90%）at the flux of 2.22 m L/min for 420 min.The Fe@NC-800/AG composite with hierarchical pore structure greatly reduced diffusion resistance of pollutants and the 3D compressible property made Fe@NC-800/AG composite can be easily separated from aqueous solution,which reduced secondary pollution and improved recycling performance.This study provided a feasible strategy to immobilize MOFs-derived powders into compressible,which showed excellent recyclability in wastewater treatment.（Chapter 6）...