Preparation Of MOF-derived Magnetic Porous Carbon And Its Adsorption Performance For Dye

Metal-organic framework derived porous carbon(MOF-C)is a new type of carbon material developed in recent years.It has received widespread attention because of its wide variety and easy to doping elements.Magnetic porous carbon is easy to recycle and has high stability,so it has been widely applied in the field of adsorption and catalysis.However,there are still some problems that magnetic materials was hard to distributed in carbon uniformly and specific surface area of magnetic porous carbon is low.In this paper,magnetic MOF-C with large specific surface area were prepared by using metal-organic framework with ferromagnetic metal as precursor.Effects of carbonization temperature and time on the MOF-C were studied,and MOF-C was then used as the adsorbent for removal of dyes.The adsorption mechanism was revealed.Co-MOF,Ni-MOF,Zn-MOF were synthesized using solvothermal method with Co2+,Ni2+,Zn2+as cental metal ions,1,4-terephthalic acid and 1,3,5-trimellitic acid as ligands,and DMF as solvent.A series of MOF-C materials were prepared by carbonization of MOFs in nitrogen atmosphere for 30?240 min at 450-950?.The maximum specific surface area of Co-MOF-C and Ni-MOF-C were 195 and 162 m2/g,respectively,and the saturation magnetic strength were 68.71 and 32.27 emu/g,respectively.The magnetic properties of MOF-C were uniform and no aggregation phenomenon was observed by EDS.With the carbonization temperature rises from 750 ? to 950 ?,the specific surface area of Zn-MOF-C increased from 205 m2/g to 567 m2/g.Co-Zn-MOF and Ni-Zn-MOF were synthesized using solvothermal method with Co-MOF and Ni-MOF added to DMF solution of Zn2+ and 1,4-terephthalic acid.A series of MOF-C materials were prepared by carbonization of MOF in nitrogen atmosphere and 30?240 min at 450?950?.The maximum specific surface area of Co-Zn-MOF-C and Ni-Zn-MOF-C reached 1093.74 m2/g and 808.26 m2/g,respectively,which was 4.5 and 3 times higher than that of Co-MOF-C and Ni-MOF-C.The result of EDS showed that the magnetic material is uniformly distributed with saturation magnetic intensities of 7.71 and 4.1 5 emu/g.The magnetic MOF-C were used to adsorb Rhodamine B and methylene blue.Effects of pH value,initial concentration,adsorption time,temperature and other factors on the performance of magnetic MOF-C adsorbed dye were studied.The adsorption mechanism of MOF-C was investigated by fitting adsorption isotherm,adsorption kinetics and adsorption thermodynamic model.The results showed that the adsorption isotherm of MOF-C on Rhodamine B and methylene blue conformed to the Langmuir adsorption model and the adsorption kinetics agreed with pseudo-second-order model,which indicated that the adsorption process was homogeneous,monolayer,and adsorption was mainly achieved by electron transfer or share between adsorbent and dye.Moreover,(?)H and AS values were positive,and most of(?)G values were negative,indicating that the adsorption process was spontaneously endothermic reaction.Co-Zn-MOF-C-950?-180min had the strongest adsorption capacity,and its saturated adsorption capacity reached 347 and 780 mg/g respectively.After five cycles of adsorption and desorption experiments,the adsorption capacity of Rhodamine B and methylene blue were approximately 30%and 23%off,showing a good cyclic adsorption capacity.