The Study On The Preparation And The Adsorption Performance Of Co Based Metal Organic Frameworks

Metal-organic frameworks(MOFs),a crystalline porous material with a regular channel or hole structure formed by self-assembly of organic ligands and metal ions,have diverse compositions and structure types,low crystal density,tunable pore size,coordinatively unsaturated and high specific surface area.It has great potentials in the field of adsorption and separation of gas,catalytic performance,electromagnetic materials,adsorption of organic dyes,drug carrier and so on.It has attracted the attention of scholars.Co-MOFs,as a kind of typical MOFs,have applicated in hydrogen storage,adsorption of organic dyes,supercapacitor material,et al.But,there have been a bit reports on Co-MOFs for the removal of organic dyes from the waste water.So,in this paper,preparation parameters and their effects on the adsorption performance of Co-MOFs was studied.In this paper,Co-MOFs was synthesized by microwave assisted ball milling at room temperature,utilizing 1,3,5-benzenetricarboxylic acid and Cobalt(II)acetate tetrahydrate.The samples were characterized by XRD,SEM,TGA and BET methods to make sure the influence of the synthetic conditions(such as,molar ratio of the raw materials,the time of synthesis,the temperature of vacuum drying)on the materials microstructure characteristics.And it also using ultrasonic assisted ball milling to prepare Co-MOFs,as a comparative experiment.The results show that the change of the synthetic conditions have a great influence on the microstructure characteristics of samples,especially the change of the molar ratio of the raw materials,which can make the microstructure and morphology changed obviously.The adsorption properties of Co-MOFs on Congo red(CR)under different preparation conditions were investigated by the isothermal adsorption,adsorption kinetics and adsorption thermodynamics.It was found that the maximum adsorption capacity(fitted by Langmuir adsorption isotherm)of the Co-MOFs(with 30 min’s synthesis time,90 ℃ vacuum drying and 1:1 molar ratio of the raw material)toward Congo red reached 4883 mg/g,and the adsorption experiment reached equilibrium in 30 min.Electrostatic attractions is thought to play an important role in the adsorption of CR onto the Co-MOFs.The adsorption capacity of Co-MOFs(synthesized by microwave assisted ball milling)on CR was much higher than previous reports,which indicated that Co-MOFs has a favorable application foreground in the field of CR adsorption.