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With the continuous research and development of amidoxime (AO)‐based adsorbents, industrialization production of uranium from seawater gradually becomes a reality. However, the currently available AO‐based adsorbents still suffer from low adsorption rate and poor selectivity. Herein, vertically aligned polyamioxime–graphene oxide (VA‐PG) sheet membrane is fabricated by directional freeze casting. The run‐through microchannels contribute to the free diffusion of uranyl ions (UO22+), leading to the fast adsorption kinetics. Furthermore, partially reduced graphene oxide allows high photothermal conversion efficiency and rapid in‐plane heat transfer, resulting in the fast temperature rise under simulated sunlight irradiation. Because of the endothermic behavior of UO22+, light‐irradiated VA‐PG can simultaneously satisfy the requirements of high adsorption capacity (13.63 mg‐U g‐Ads−1), high adsorption rate (0.43 mg g−1 day−1), and excellent selectivity toward U(VI) over V(V) (U/V = 1.24) in natural seawater, indicating the right direction for a breakthrough in the field of uranium extraction from seawater. [ABSTRACT FROM AUTHOR]

[Display omitted] • Wood aerogel with run-through microchannel arrays was used for in-situ growth of MOF. • Bilayer MOF architecture was developed to boost the loading content of MOF. • CMPM adsorbents exhibited good reversible compressibility and fragility resistance. • The recycle CMPM exhibited high selective adsorption capacity in natural seawater. Metal-organic frameworks (MOFs) have been widely applied in the recovery of specific guest molecules due to their excellent properties including high porosities, adjustable pore size and abundant chelating functions. However, the granular MOF crystals bring a great challenge to the recycling and reusing from aqueous media, and thus seriously limit their practical application. In this work, MOF bonded wood aerogel prepared by means of in-situ growth strategy was developed for uranium extraction from natural seawater. Eco-friendly and biocompatible wood aerogel possesses run-through microchannel arrays enclosed by aligned cellulose nanofibers (CNFs), contributing to the free and fast diffusion of uranyl ions (UO 2 2+), and thus result in the sufficient coordination with active chelation sites of MOF crystals. To increase the loading content of MOF, bilayer MOF architecture (CMPM) was prepared by using hydroxyl functional groups in CNFs and polydopamine (PDA) coating as nucleation centers of MOF, respectively. The resultant CMPM adsorbents exhibited good reversible compressibility and fragility resistance, which were critical to extend its service life. Moreover, the excellent photothermal conversion capability of PDA enabled CMPM to acquire high temperature under simulated sunlight irradiation. Owing to the apparently endothermic behavior of UO 2 2+, light-irradiated CMPM achieved high adsorption capacity (5.81 mg-U/g-Ads) together with excellent UO 2 2+ selectivity in natural seawater after 30 days. Therefore, this work provides a feasible solution in promoting the practical application of MOF adsorbents. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mussel-inspired photothermal PAO hydrogel adsorbents were successfully fabricated. • PDA contributes to excellent hydrophilicity and photothermal conversion capacity. • Light irradiation yields the high uranium sorption capacity of 12.67 mg-U/g-Ads. • Excellent adsorption selectivity towards U(VI) over V(V) can be obtained. • Fe3+ coordination endows with excellent tensile strength and self-recovery ability. The efficient development of selective adsorbents for uranium extraction from seawater is necessary for their potential application in nuclear power generation. The amidoxime-based adsorbents have been recognized as the potential candidates, whereas they still suffer from a much higher affinity towards V(V) present in the seawater over U(VI), leading to the extremely limited commercial use. In this work, we develop a novel mussel-inspired photothermal polyamidoxime (PAO) hydrogel adsorbent, in which polydopamine (PDA) chains are linked to PAO (PDA-PAO) via Michael addition. Dual-crosslinked Fe@PDA-PAO hydrogel structure is constructed by noncovalent bonds between the catechol of PDA chains (e.g. π-π stacking and hydrogen bonds) as well as ionic coordination of Fe3+. PDA contributes to the improved hydrophilicity and high photothermal conversion efficiency. As a result, after immersing in real seawater for 6 weeks, light-irradiated Fe@PDA-PAO hydrogel delivers high uranium sorption capacity (12.67 mg-U/g-Ads) together with high U/V mass ratios (1.17), which are superior to currently available hydrogel adsorbents. Meanwhile, Fe3+ coordination endows Fe@PDA-PAO hydrogel with excellent tensile strength and self-recovery ability, which are of great significance to withstand the harsh conditions of ocean environment for practical applications. The results presented here reveal that Fe@PDA-PAO hydrogel holds tremendous potential for practical applications in the uranium-selective extraction from seawater. [ABSTRACT FROM AUTHOR]

[Display omitted] • MOF-bonded carbon sponge is designed for photothermally enhancing U(VI) adsorption. • The mass loading of UiO-66-NH 2 prepared by in-situ growth can reach up to 85 wt%. • The monolithic MOF adsorbent exhibits favorable elastic and recyclable performance. • The selectivity of U(VI) can be improved when exposure to light irradiation. • Light irradiation yields a 32.37% increase in the U(VI) adsorption amount than dark. Extraction of radioactive uranium from the natural seawater is regarded as one of the most promising ways to address the shortage of uranium resources. As a kind of potential uranium adsorbent, more attention has been paid to metal–organic framework materials (MOFs) due to large specific surface area and high ion selectivity. Currently, however, MOF adsorbents are hardly applied to the real seawater in view of the relatively low uranium adsorption capacity and recyclable issues. Herein, we present the monolithic MOF adsorbent with photothermally enhancing uranium adsorption capacity. Carbon sponge (CS) substrate with macroporous open cell structure was used as excellent photothermal conversion material. Zr-MOF (UiO-66-NH 2) crystals were in situ grown on the fibrils network of polydopamine (PDA) pre-coated CS to obtain UiO-66-NH 2 @CS-PDA adsorbent. It is found that UiO-66-NH 2 coating with perfect coverage and good adhesion has a high mass loading (>85 wt%). As a result, UiO-66-NH 2 @CS-PDA adsorbents exhibited the advantage of high-selectivity, high-affinity and cycling stability. Compared with the dark condition, the uranium adsorption amount was increased by 32.37% after 4 weeks in the natural seawater under simulated solar irradiation, which was mainly ascribed to the endothermic behavior of uranium adsorption process. Moreover, the elasticity attribute of CS was essential for sustenance of volume variation buffering during seawater flow. As a recyclable and favorable elastic large-scale monolithic MOF adsorbent, UiO-66-NH 2 @CS-PDA holds great promise for extracting uranium from the natural seawater. [ABSTRACT FROM AUTHOR]