Chen Wang,Chao Xiong,Yali He,Chen Yang,Xiteng Li,Jianzhong Zheng,Shixing Wang
A novel magnetic Zr-MOF named Ni 0.6 Fe 2.4 O 4 -UiO-66-PEI was synthesized by modifying UiO-66-NH 2 with Ni 0.6 Fe 2.4 O 4 and polyethyleneimine and its sorption characteristics for two representing heavy metals Pb(II) and Cr(VI) in water were examined. This material showed good thermal stability and was sufficiently magnetic to allow effective solid-liquid separation. The material had a maximum adsorption capacity of 273.2 mg/g for Pb(II) at pH 4.0 and 428.6 mg/g for Cr(VI) at pH 3.0, as obtained from the model fitting by the Hill equation. The sorption kinetics for both heavy metals on the material was fast, with adsorption equilibrium established in 60 min and 30 min for Pb(II) and Cr(VI), respectively. Model fitting of the kinetic data showed that Pb(II) and Cr(VI) sorption on Ni 0.6 Fe 2.4 O 4 -UiO-66-PEI followed the pseudo-second-order model. This material had good selectivity for competing ions, and still hold fairly good binding capacities after 5 times of regeneration. Adsorption mechanisms for Pb(II) and Cr(VI) by Ni 0.6 Fe 2.4 O 4 -UiO-66-PEI were proposed by analyzing FTIR, XPS and the electrokinetic property of the material. Specifically, Pb(II) adsorption on Ni 0.6 Fe 2.4 O 4 -UiO-66-PEI could be attributed to chelation of Pb(II) with the imine/amine functional groups in the material’s matrix, while Cr(VI) adsorption might stem from a combination of electrostatic attraction, chelation and redox reaction. It seems that Ni 0.6 Fe 2.4 O 4 -UiO-66-PEI could be used as a green and environmental-friendly material for heavy metals removal, particularly from acidic water streams.
A facile preparation of magnetic MOF composites with flexible mercapto group pendants in their pores is realized through solvent-assisted ligand exchange (SALE) under mild conditions in water, and terephthalate in UIO-66 is replaced with mercaptoacetic acid (MAA). After the SALE processing, the crystallinity, porosity, and superparamagnetism of the mercapto functionalized magnetic Zr-MOF (MFC-S) are well maintained, and the obtained MFC-S exhibits a higher adsorption capacity (282 mg g−1) for Hg2+ than that of the magnetic Zr-MOF (MFC-O). Furthermore, the prepared MFC-S can be regenerated easily by liquid desorption after adsorption of metal ions and be reused more than 5 times without obvious decrease in removal performance. The proposed SALE method for the preparation of mercapto functionalized magnetic MOF composites (MFCs) is easy-to-operate and low cost, providing not only a reliable porous MFC platform for the removal of metal ions, but also a simple and efficient synthesis route for the preparation of functionalized MFCs which cannot be achieved through conventional approaches.
危险品化学品经营许可证（带存储）