The Study On The Preparation And The Adsorption Performance Of Ni Based Metal Organic Framework Composites

Metal-organic frameworks?MOFs?,as a new class of crystalline porous materials based on metal ions connected by organic linkers,have drawn more and more attention in the scientific community due to their high porosity,large surface area and tunable pore size.MOFs have been widely investigated in the fields of catalysis,gas adsorption and storage,drug delivery,separation,luminescenceand magnetism.The aim of this paper is to study the performance of Ni-MOFs and Ni-MOFs/GO to adsorb Congo Red?CR?and to uncover the adsorption mechanism.Firstly,ultrasonic wave-assisted ball milling was used to synthesis Ni-MOFs and Ni-MOFs/GO.At the same time,Ni-MOFs was also synthesized by ultrasonic wave-assisted ball milling,ultrasonic wave and ball milling.All the samples were characterized by X-ray diffraction?XRD?,thermogravimetric analysis?TGA?,N₂adsorption-desorption isotherms,Raman spectroscopy and scanning electron microscope?SEM?methods.The results showed ultrasonic wave and mechanical force played an important role in the synthesis of MOFs and verified the effective combination between GO and Ni-MOFs.This paper also studied the effect of adsorption time,initial concentration,the amount of adsorbent and temperature on the adsorption of CR.The results showed that the adsorption of CR over Ni-MOFs can reach equilibrium state in a very short time;The adsorption amount of CR over Ni-MOFs increased with increasing the initial concentration of CR solution;The adsorption process was a endothermic process.The higher the temperature,the higher the adsorption amount of CR onto Ni-MOFs.Utilizing Langmuir isotherm model,Freundlich isotherm model,Temkin isotherm model,Dubinin–Radushkevich isotherm model,kinetic model and thermodynamic model to fit the experimental data:As to Ni-MOFs and Ni-MOFs/GO,the results correspond well with the Freundlich isotherm;The experimental results of the two MOFs correspond well with those of the pseudo-second-order kinetic model and the adsorption process wasa spontaneous and endothermic process.Comparing the adsorption effect of Ni-MOFs and Ni-MOFs/GO,it can be found that the adsorption amount of Ni-MOFs/GO is higher than that of Ni-MOFs,indicating that the addition of GO is beneficial to improve the adsorption amount of CR.Comparing the adsorption effect of Ni-MOFs/GO dried at different temperatures and the adsorption capacity of CR at various pH,it is found that increasing the number of active metal sites is an effective method to improve the adsorption capacity of dye.Moreover,electrostatic interaction and acid-base interaction are the main adsorption mechanism.