Adsorption Kinetics of Methylene Blue on Synthesized DMF-MIL-101(Cr), a DMF-functionalized Metal-organic Framework

摘要

An N,N-dimethylformamide(DMF)-ftmctionalized metal-organic framework, namely, DMF-MIL-101(Cr), was prepared and then used for the adsorptive removal of methylene blue (MB),a cationic dye, from aqueous solutions. MIL-101(Cr) was synthesized by the hydrothermal method. Next, by dipping the MIL-101(Cr) sample in DMF, DMF-MIL-101(Cr) was synthesized. The results of X-ray diffraction analysis, Fourier transform infrared spectroscopy, and thermogravimetric analysis confirmed that DMF and MIL-101 could be combined successfully. More importantly, the MB uptake capacity of DMF-MIL-101(Cr) was significantly higher than that of MIL-101(Cr). Unlike MIL-101 (Cr),DMF-MIL-101(Cr) could adsorb the entire MB in a solution with a concentration of 10.92 mg/L,owing to the electrostatic interactions between DMF and the MB molecules. In 100 mL of a 10.92-mg/L MB solution, DMF-MIL-101(Cr) can reach a state of absorbance equilibrium within 10 min. After that, the adsorption process exhibited the characteristics of a zero-order reaction. This result indicates that it may be possible to exploit different functionalization methods and improve the rate of adsorption of dyes onto metal-organic frameworks