A facile synthesis of a Ce-based MOF at room temperature for effective adsorption of methylene blue

Abstract

Synthesizing stable MOF materials with good adsorption capability in a relatively green way is well worth investigating. In this work, a stable Ce-UiO-66-NH₂ MOF was constructed from Ce(IV) salts and a bifunctional ligand, 2-amino terephthalic acid, in a mixture of water and ethanol at room temperature. The MOF solid was fully characterized and its adsorption properties for methylene blue were investigated in detail. Ce-UiO-66-NH₂ showed excellent removal ability of MB over a wide pH range, the adsorption process followed a pseudo-second-order kinetic model, and the isothermal adsorption data fit well with a Langmuir model with a maximum capacity of 427 mg g⁻¹. Moreover, a spontaneous heat adsorption process was concluded from thermodynamic study, and this MOF sorbent can be reused for several cycles with its structural stability maintained. A possible mechanism for MB adsorption was also proposed.