Novel Fluorine-Pillared Metal–Organic Framework for Highly Effective Lithium Enrichment from Brine

Abstract

The continuously developing lithium battery market makes seeking a reliable lithium supply a top priority for technology companies. Although metal–organic frameworks have been extensively researched as adsorbents owing to their exceptional properties, lithium adsorption has been scarcely investigated. Herein, we prepared a novel cuboid rod-shaped three-dimensional framework termed TJU-21 composed of fluorine-pillared coordination layers of Fe–O inorganic chains and benzene-1,3,5-tricarboxylate (BTC) linkages. Besides thermal and chemical robustness, a remarkably high lithium uptake of about 41 mg·g–1 was observed on TJU-21 as a fast-spontaneous endothermic process. Single-crystal X-ray diffraction demonstrated that the adsorbed lithium was located in the cavity symmetrically assembled by iron sites and organic ligands between adjacent layers, while another kind of cavity in the framework circled by Fe–O–Fe–O–Fe–O–Fe chains and shared BTC linkages was occupied by hydrogen-bonded water molecules. Lithium adsorption resulted in decreased curviness of the coordination layers, and the binding energy change at O 1s as well as the increased Fe 2p peak, suggested potential interaction with iron sites. The practicability of TJU-21 as a lithium adsorbent was further proved by the considerable capacity and selectivity in simulated salt brines with excellent reusability.

Highly efficient lithium adsorption and stable isotope separation by metal–organic frameworks

“…Compared with previously reported Li adsorbents, [21][22][23][24][25] the adsorption capacity of the four MIL-100 materials investigated in this study increased by different degrees (Table S1, ESI †).…”

“…Compared with the lithium adsorption materials reported in the literature, [21][22][23][24][25] seven MOF materials initially investigated in this research exhibited comparable separation factors with 7 Li preference and excellent adsorption capacity in high concentration lithium solution (Fig. 1 and Table S1, ESI †).…”

“…The separation factors of the four materials are close to those of the reported adsorbents (Table S1, ESI †). [21][22][23][24][25] The lithium isotope separation factor decreased in the order MIL-100(Al) 4 MIL-100(Sc) 4 MIL-100(Fe) 4 MIL-100(Cr), and there is an obvious trade-off between the separation factor and the adsorption capacity.…”

“…18 In view of the large specific surface area of MOFs, several classes of MOFs with good water stability, thermal stability and chemical stability were selected in order to be better applied to lithium adsorption. 19,20 Furthermore, Jiang et al 21 prepared a novel three-dimensional framework termed TJU-21 composed of fluorine-pillared coordination layers of Fe-O inorganic chains and benzene-1,3,5-tricarboxylate (BTC) linkages, which exhibited excellent lithium adsorption capacity and the possible interaction between the coordination layer and lithium was demonstrated. Given the specific interaction of Li + and coordinative frameworks, it is possible to achieve the selective adsorption of lithium isotopes using MOFs as adsorbents, which is easy to operate and has little potential harm to the environment.…”

Efficient Capture of Th(IV) and U(VI) by Radiation-Resistant Oxygen-Rich Ion Traps Based on a Metal–Organic Framework

“…The coordination of metal ions with more O atoms will enlarge the electron cloud density and promote the formation of a strong chelation effect. The carboxylic MOF commonly contains abundant O atoms, while in most cases, the distance of adjacent O atoms is so far that only one O atom can interact with metal ions simultaneously. , On the contrary, rational distance or distributions of O atoms will promote the formation of an ion trap microenvironment, which has strong capturing ability for metal ions. − Thus, making full use of dense O atoms of MOFs and even constructing O-rich ion traps is a significant and convenient approach. However, similar attempts have been rarely reported until now.…”