Precisely modulating the branching functional groups of MIL-53(Al) for highly efficient sequestration of uranium. Issue 2 (April 2023)

• Record Type: Journal Article
• Authors: Liu, Shuya; Ma, Xinjie; Liu, Yuxin; Chen, Weiwei; Ai, Yuejie; Li, Kexin; Ye, Xiushen; Fang, Ming; Tan, Xiaoli
• Is Part Of: Journal of environmental chemical engineering. Volume 11:Issue 2(2023)
• Publication Date: 2023-04
• Subjects: Modulated MOF -- U(VI) adsorption -- Carboxyl/phosphite groups -- Steric hindrance -- DFT; Chemical engineering -- Environmental aspects -- Periodicals; Environmental engineering -- Periodicals; Chemical engineering -- Environmental aspects; Environmental engineering; Periodicals; 660.0286
• DOI: 10.1016/j.jece.2023.109393
• Languages: English
• ISSNs: 2213-2929

Abstract

Abstract: To fully utilize the customizable characteristics of metal-organic framework (MOF) materials in environmental applications, it is important to precisely modulate the branching groups of MOFs for improved performance. In this work, MIL-53(Al) was modulated by different numbers of nitrogen atoms and carboxyl groups/phosphite groups (MOF-N2 -(COOH)3, MOF-N3 -(COOH)4, and MOF-N2 -(PO(OH)2 )3 ) via a post-synthesis modification method, and the influence of functional groups and chain length on adsorption and the mechanism of modified groups on the adsorption of uranium (U) are demonstrated. Batch experiments suggest the removal of U(VI) reaches 37%, 27%, and 90% for MOF-N2 -(COOH)3, MOF-N3 -(COOH)4 and MOF-N2 -(PO(OH)2 )3, respectively (pH = 4.0, T = 25 ℃, I = 0.01 M NaNO3 ). The surface complexation between UO2 2+ and the surface of functional groups on the modulated MOF dominates the adsorption. Nevertheless, the steric hindrance in MOF porous structure can explain the inferiority of U(VI) adsorption on MOF-N3 -(COOH)4 (27%) to MOF-N2 -(COOH)3 (37%). MOF-N2 -(PO(OH)2 )3 is more conducive to uranyl adsorption than MOF-N2 -(COOH)3 or MOF-N3 -(COOH)4, which is due to better affinity of U(VI) to phosphate group than the carboxyl group by density functional theory (DFT) calculation. Moreover, the excellent regeneration performance and U(VI) adsorption of MOF-N2 -(PO(OH)2 )3 in natural water or wastewater further confirmed the practical application of modulated MOFs in practical application. Graphical Abstract: ga1 Highlights: The modulated MOFs branching with distinct nitrogen atoms backbone were prepared via a post-synthesis modification method. The surface complexation between the functional groups of MOF-FGn and U(VI) is the main mechanism. The affinity of phosphite group for U (VI) is higher than that of carboxyl group via theoretical and experimental studies. Steric hindrance in MOF can explain the inferiority of U(VI) adsorption on MOF-N3 -(COOH)4 than MOF-N2 -(COOH)3 .