Preparation Of Spongy Supported MIL-53(Fe) Material And Its Adsorption Ability For Toluene

Volatile organic compounds（VOCs）mainly include alkanes,aromatic hydrocarbons,olefin,halogenated hydrocarbons,esters,etc.,which are one of the important sources of air pollution and the main precursor of haze formation.Therefore,it is urgent to deal with and control VOCs gas.MOFs materials have the advantages of large surface area,rich pore structure,unsaturated metal coordination sites and so on,which has its unique advantages in the field of adsorption.In this thesis,MIL-53（Fe）was selected as the core of the loading material,polydopamine was added,and they were loaded together on the melamine sponge（MF）to prepare PM@MF material to adsorb toluene.By optimizing the reaction temperature,time and ratio of reactants,the optimum reaction conditions for its preparation were explored.The morphology and structure of toluene on PM@MF were characterized by BET,XRD,FT-IR,SEM and other means,and the adsorption kinetics,adsorption isotherm curve and thermodynamics of toluene on PM@MF were studied,including the following contents:（1）MIL-53（Fe）was synthesized by solvent-thermal method with ferric chloride hexahydrate（Fe Cl₃·6H₂O）and terephthalic acid（1,4-BDC）as the reactants and N,N-dimethylamide as the solvent（DMF）,and the optimal preparation conditions of MIL-53（Fe）were explored.（2）MIL-53（Fe）prepared under optimal conditions was selected as the carrier,mixed with polydopamine（PDA）and loaded on melamine sponge（MF）at temperature of 330℃,PM@MF was prepared,and the optimal conditions for the preparation of PM@MF were explored.PM@MF was prepared with large surface area up to 1069.33 m²/g.It is a kind of material combining micropore and mesoporous;have good thermal stability;the adsorption effect is better in weak acidic environment.（3）Compared with the material before loading,the static adsorption capacity of PM@MF adsorbent for toluene was significantly increased,and the maximum saturation adsorption capacity was 168.0 mg/g before loading and up to 485 mg/g after loading.（4）The adsorption process of toluene molecules on PM@MF is more suitable to be described by pseudo-first-order kinetic model.The adsorption mechanism isπ-πstacking between benzene ring in toluene and the ligand molecules in PM@MF.The internal diffusion process is the main factor affecting the adsorption rate of toluene,and the external diffusion and surface adsorption process also have effects.Freundlich isotherm equation is more suitable to describe the adsorption process,which is multi-layer adsorption.The adsorption process is spontaneous and exothermic.