Modification Of Metal-organic Framework UiO-66 And Its Adsorption Performance For Tetracycline

Metal-Organic Frameworks,as a new class of crystalline porous materials,have great applications in adsorption,especially UiO-66 with high hydrothermal stability.However,the microporosity of UiO-66 blocks large molecules（such as tetracycline）from accessing the channels.In this work,the pore structure of UiO-66 was modified by adding template,doping metal and carbonizing in order to obtain hierarchical（microporous-mesoporous）materials with high adsorption capacity.The conditions,for example,the content of template and carbonization time,were investigated to investigate their influence on pore structure,crystal morphology and thermal stability so on.The main work and conclusions are as follows:The microporous material UiO-66 was synthesized by solvothermal method using ZrCl₄ as the metal source,1,4-terephthalic acid as the organic ligand,and N,N-dimethylformamide as the solvent.The BET specific surface area was 1160.10 m²/g,the average pore size was 1.77 nm,and the total pore volume was 0.51 cm³/g.It could maintain the skeleton structure without collapse at 500℃.The maximum tetracycline adsorption capacity of UiO-66 was 39.78 mg/g at303K and 30 mg/L.The adsorption kinetics and isotherms of tetracycline was well described by using pseudo-second-order model,particle-diffusion model,and Langmuir isotherm model.In addition,UiO-66 showed a certain ability to resist salt and a good cycle adsorption capacity.Last but no least,there may existe three kinds of interaction forces:π-πmutual accumulation,hydrogen bonding and electrostatic attraction.UiO-66/n SDBS was synthesized by usig sodium dodecylbenzenesulfonate（SDBS）as mesoporous template.N₂ adsorption/desorption analysis results showed that UiO-66/n SDBS was a hierarchical material,which had the highest BET specific surface area of 1333.36 m²/g,the largest average pore size of 6.07 nm,and the largest total pore volume of 2.11 cm³/g.The maximum tetracycline adsorption of UiO-66/3SDBS was 89.09 mg/g and the adsorption equilibrium time was 210 min at 303K and 30 mg/L.NiUiO-X was synthesized by doping nickel nitrate（Ni（NO₃）₂·6H₂O）.Ni UiO-1 synthesized with a molar ratio of Zr:Ni of 1:1 was a hierarchical material.It had the BET specific surface area of 1455.20 m²/g,the average pore size of 2.42 nm,and the total pore volume of 0.79 cm³/g.Besides,the maximum tetracycline adsorption of Ni UiO-1 was 49.25 mg/g and the adsorption equilibrium time was 300 min at 303K and 30 mg/L.UiO-66 was used as a precursor to prepare UiO-66-C in N₂ atmosphere for 30～150 min at600℃.UiO-66-C was treated by using HF solution to obtain UiO-66-600℃-T-HF.Among them,UiO-66-600℃-30min-HF had the highest BET specific surface area of 1974.17 m²/g,lagest average pore size of 3.28 nm and lagest total pore volume of 1.61 cm³/g.Adsorption experiments indicated that the maximum tetracycline adsorption capacity of UiO-66-600℃-30min-HF was294.75 mg/g at 303K and 30 mg/L.