Strategies toward the Synthesis of Advanced Functional Sorbent Performance for Uranium Uptake from Seawater

Heterometallic uranyl (hydroxyethyl)iminodiacetic acid (heidi) complexes: Molecular models for U(VI) uptake in complex media

Amidoximated absorbents (AO-PAN) effectively remove U(VI) from aqueous solution, but previous studies reported more variability for complex natural waters that contain additional confounding ions and molecules. Ternary phases containing U(VI), M(III) (M = Fe(III), Al(III), Ga(III)), and organic molecules exist under these conditions and cause heterogeneous U(VI) uptake on AO-PAN. The goal of the current study is to provide additional insights into the structural features ternary complexes using N-(2-hydroxyethyl)-iminodiacetic acid (HEIDI) as the model organic chelator and explore the relevance of these species on U(VI) capture. Three model compounds ([(UO2)(Fe)2(μ3-O)(C6NO5H8)2(H2O)4] (UFe2), ([(UO2)(Al)2(μ2-OH)(C6NO5H8)2(H2O)3] (UAl2) and [(UO2)(Ga)2(μ2-OH)(C6NO5H8)2(H2O)3] (UGa2)) were characterized by single-crystal X-ray diffraction. Raman spectra of the model compounds were compared with solution data and the ternary phases were noted in the case of Al(III) and Ga(III), but not in the Fe(III) system. U(VI) adsorption onto AO-PAN was not impacted by the presence of HEIDI or the trivalent metal species.

Shear-induced fabrication of SiO2 nano-meshes for efficient uranium capture

The extraction of uranium from seawater and the safe treatment of wastewater containing uranium (VI) were important to ensure the sustainable development of nuclear-related energy sources. Two-dimensional silica nanomaterials have been extensively investigated in the field of uranium adsorption due to their high adsorption capacity, short equilibration times, and easily modified surface groups. However, the two-dimensional mesoporous silica nanomaterial preparation has become a challenge due to the lack of natural sheet templating agents. The reason will hinder the development of silica nanomaterials for uranium extraction. Here, the specific surface area silica nanomeshes (HSMSMs) uranium adsorbent was prepared by a high shear method to induce nanobubble formation. HSMSMs showed a high uranium adsorption capacity of 822 mg_-U/g_-abs in seawater with the uranium adsorption concentration was 50 mg/L, which was approximately 2 times higher than the conventional mesoporous silica nanomaterials. Compared to HSMSMs, the amidoxime-modified high specific surface area silica nanomesh (HSMSMs-AO) demonstrated good selectivity for U(VI), and the uranium ions uptake was 877 mg_-U/g_-abs in 50 mg/L uranium-spiked simulated seawater. Due to HSMSMs-AO's stable chemical properties and high mechanical strength, HSMSMs-AO also displayed long service life. Benefiting from the simple preparation method and high adsorption capacity of HSMSMs, HSMSMs could be a promising candidate for large-scale extraction of uranium from seawater.