Ship-in-a-bottle CMPO in MIL-101(Cr) for selective uranium recovery from aqueous streams through adsorption

Abstract

Mesoporous MIL-101(Cr) is used as host for a ship-in-a-bottle type adsorbent for selective U(VI) recovery from aqueous environments. The acid-resistant cage-type MOF is built in-situ around N,N-Diisobutyl-2-(octylphenylphosphoryl)acetamide (CMPO), a sterically demanding ligand with high U(VI) affinity. This one-step procedure yields an adsorbent which is an ideal compromise between homogeneous and heterogeneous systems, where the ligand can act freely within the pores of MIL-101, without leaching, while the adsorbent is easy separable and reusable. The adsorbent was characterized by XRD, FTIR spectroscopy, nitrogen adsorption, XRF, ADF-STEM and EDX, to confirm and quantify the successful encapsulation of the CMPO in MIL-101, and the preservation of the host. Adsorption experiments with a central focus on U(VI) recovery were performed. Very high selectivity for U(VI) was observed, while competitive metal adsorption (rare earths, transition metals...) was almost negligible. The adsorption capacity was calculated at 5.32mg U/g (pH 3) and 27.99mg U/g (pH 4), by fitting equilibrium data to the Langmuir model. Adsorption kinetics correlated to the pseudo-second-order model, where more than 95% of maximum uptake is achieved within 375min. The adsorbed U(VI) is easily recovered by desorption in 0.1M HNO. Three adsorption/desorption cycles were performed.

The MOF+ Technique: A Potential Multifunctional Platform

“…[22] Thus, the moste ffective method is reducing soluble U VI to insoluble U IV ,a nd al arge number of reducing agentsa nd approaches have been explored to date. [23] Among these explorations, FeSO 4 received much interest duet oi ts low-cost and highr eduction ability,m aking it to be one of the best choices. However, as disclosed in the literature, the reduction of U VI -to-U IV by FeSO 4 musti solate from oxygen and carbon dioxide, mainly due to the competing oxidation from oxygen and formationo fs table coordination fragment from CO 2 .…”

“…Uranium mining and development causes a series of uranium pollution, due to its high mobility in aquatic media and aggregation in bioenvironments . Thus, the most effective method is reducing soluble U VI to insoluble U IV , and a large number of reducing agents and approaches have been explored to date . Among these explorations, FeSO 4 received much interest due to its low‐cost and high reduction ability, making it to be one of the best choices.…”

Preparation of a magnetic reduced-graphene oxide/tea waste composite for high-efficiency sorption of uranium

“…Different types of adsorbents have been successfully used for uranium removal from aqueous solutions, including natural polymers 16,17 , inorganic compounds 18,19 , carbon nanomaterials 20,21 , metal-organic frameworks 22,23 and biomass 24,25 . The economy of the adsorbents used is of great importance to reduce wastewater treatment costs.…”

Facile preparation and adsorption performance of graphene oxide-manganese oxide composite for uranium

“…Therefore, the high-efficiency removal of uranium from aqueous solutions has become a hot research topic 1,2 . Sorption 3–5 , which is superior to other techniques (e.g., bioreduction and precipitation 6 , reverse osmosis 7 , and ion exchange 8,9 ), has been widely applied in the wastewater treatment process due to its merits, such as economic, operation simplicity and no secondary pollution. However, most of adsorbents exhibit some disadvantages of low sorption capacity, high cost and lack of environmentally-friendly properties.…”