Selective recovery and separation of rare earth elements by organophosphorus modified MIL-101(Cr)

Abstract

Development of state-of-the-art selective adsorbent materials for recovery of rare earth elements (REEs) is essential for their sustainable usage. In this study, a metal-organic framework (MOF), MIL-101(Cr), was synthesized and post-synthetically modified with optimised loading of the organophosphorus compounds tributyl phosphate (TBP), bis(2-ethylhexyl) hydrogen phosphate (D2EHPA, HDEHP) and bis(2,4,4-trimethylpentyl) phosphinic acid (Cyanex®-272). The materials were characterized and their adsorption efficiency towards Nd 3+ , Gd 3+ and Er 3+ from aqueous solutions was investigated. The MOF derivatives demonstrated an increase in adsorption capacity for Er 3+ at optimal pH 5.5 in the order of MIL-101-T50 (37.2 mg g − 1 ) < MIL-101-C50 (48.9 mg g − 1 ) < MIL-101-H50 (57.5 mg g − 1 ). The exceptional selectivity of the materials for Er 3+ against transition metal ions was over 90%, and up to 95% in the mixtures with rare earth ions. MIL-101-C50 and MIL-101-H50 demonstrated better chemical stability than MIL-101-T50 over 3 adsorption− desorption cycles. The adsorption mechanism was described by the formation of coordinative complexes between the functional groups of modifiers and Er 3+ ions.

Selective Recovery of Rare Earth Elements from Mine Ore by Cr-MIL Metal–Organic Frameworks

“…These values are closely similar to those reported by previous studies on Cr-MIL ,,, as described in detail in the Supporting Information. Furthermore, Kavun, van der Veen, and Repo reported similar findings, where a 60% reduction of the surface area of the Cr-MIL MOF upon functionalization with organophosphorus was observed, and attributed the surface area reduction to the presence of functionalized ligands incorporated into the Cr surface. The BET surface area of Cr-MIL-NH 2 is reported to be in the range of 1245–2146 m 2 ·g –1 while the pore diameter is found to be less than 10 nm. , Even though physical characterization of Cr-MIL-NH 2 synthesized in our study is noticeably different from that reported by ref , it is consistent with previous studies.…”

“…These studies highlight the importance of grafting metal clusters with appropriate functional groups to attain high REE selectivity in MOFs. Likewise, chromium MIL-based MOFs functionalized with phosphonate and carboxylate groups show high stability and selective REE adsorption capacity. , Although these studies indicate MOF adsorption capacity for REEs, most of these studies were conducted with either single-model solutions or concentration ratios of transient metals that do not represent practical scenarios. , More specifically, the performance of MOFs for recovering REEs from actual zinc mine ore leachate that contains a high concentration of Zn and other heavy metals is yet to be explored. It is essential to establish the capacity of applying MOFs for recovering REEs in actual scenarios and understanding its selectivity mechanism to enhance its practical performance.…”

“…Likewise, chromium MIL-based MOFs functionalized with phosphonate and carboxylate groups show high stability and selective REE adsorption capacity. 22,23 Although these studies indicate MOF adsorption capacity for REEs, most of these studies were conducted with either single-model solutions or concentration ratios of transient metals that do not represent practical scenarios. 20,21 More specifically, the performance of MOFs for recovering REEs from actual zinc mine ore leachate that contains a high concentration of Zn and other heavy metals is yet to be explored.…”

Low-Temperature and Additive-Free Synthesis of Spherical MIL-101(Cr) with Enhanced Dye Adsorption Performance

“…The terminal connected water molecules of MIL-101(Cr) can be removed under high temperature or vacuum conditions, which creates potential Lewis acid sites [20]. Hence, MIL-101(Cr) demonstrates quite good water stability, which makes it suitable for wide applications, especially in the presence of moisture/water conditions, such as catalysis [21,22], adsorption [23,24], separation [25,26], drug delivery [27,28], gas storage [29,30], water pollution treatment [31], and mixed matrix membranes [32,33], among others.…”

Ce-exchange capacity of zeolite L in different cationic forms: a structural investigation

“…solvent extraction (Meshram & Abhilash, 2020;Deshmane et al, 2020;Ni'Am et al, 2020), precipitation (Zhou et al, 2018;Porvali et al, 2018;Diaz et al, 2016) and ion exchange (Royen & Fortkamp, 2016). The last can exploit various materials such as active carbon (Gad & Awwad, 2007), resins (Manos & Kanatzidis, 2016) and microporous materials (Kavun et al, 2021;Royen & Fortkamp, 2016) such as zeolites.…”