Fabrication of Ce-doped MIL-100(Fe), its adsorption performance, and the mechanisms to adsorb phosphate from water

Water eutrophication caused by phosphate emissions has become a serious environmental issue. In this study, we used the solvothermal method to prepare a novel Ce-doped MIL-100(Fe). Scanning electron microscope observations suggest that Ce-doped MIL100(Fe) consisted of irregular polyhedrons in the size range of tens of micrometers. Spectroscopy results show that cerium atoms (Ce) were successfully doped into the MIL-100(Fe) frameworks. The specific surface area and pore size of the Ce-doped MIL100(Fe) were 2.6 m2/g and 3.4 nm, respectively. Adsorptive kinetics indicated that the pseudo-second-order model with a high correlation coefficient of (R2: 0.9950) fitted better than the pseudo first-order model with R2 of 0.9436. The adsorptive isotherms showed that for these adsorption reactions, the Langmuir model matched much better than the Freundlich model for this adsorption. These facts suggest that adsorption is chemical sorption, which occurred on a homogeneous surface. The adsorption capacity of the Ce-doped MIL-100(Fe) was as high as 12.03 mg/g. The adsorption capacity of the Ce-doped MIL-100(Fe) depended strongly on the solution pH, ionic strength, and the coexisted ions. The study also found that the precipitation reaction and complexation interaction might be dominated in the adsorption. This study may contribute to the design of bimetal organic frameworks, and might add new insights into the removal of phosphate. (c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).