Vertically Aligned Polyamidoxime/Graphene Oxide Hybrid Sheets’ Membrane for Ultrafast and Selective Extraction of Uranium from Seawater

Abstract

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.

Biomimetic porous cellular foam with space thermal domains for efficient uranium extraction from seawater

“…18,19 Dense amine foams are emerging materials for the adsorption of U(VI) due to their three-dimensional network structure, high open pore rate (99%), low thermal conductivity (0.04 W m −1 K −1 ) and abundant binding sites. 20,21 However, the structural limitations of dense amine foams lead to slow adsorption rates and poor selectivity for U(VI), making it impossible to perform U(VI) extraction from seawater with high efficiency. [22][23][24] Therefore, many researchers have worked on the use of the photoelectric effect and thermal assistance to accelerate the kinetics of the adsorption reaction.…”

MXene-Derived 3D Defect-Rich TiO2@Reduced Graphene Oxide Aerogel with Ultrafast Carrier Separation for Photo-Assisted Uranium Extraction: A Combined Batch, X-ray Absorption Spectroscopy, and Density Functional Theory Calculations

“…As one of the important fuels for nuclear power, uranium is one of the most promising low-carbon energy sources to achieve the dual-carbon goal. − It is estimated that there are approximately 4.5 billion tons of uranium in seawater, which is 1000 times more abundant than the proven uranium reserves on land and enough to sustain nuclear power generation for thousands of years. − In fact, uranium extraction from nuclear wastewater/seawater is considered one of the most promising and challenging separation processes because the concentration of uranium in high-salinity seawater is only 3.3 ppb in the presence of other competing metal cations. − The adsorption method has been proven to be an effective method for extracting uranium from radioactive wastewater and seawater. − However, traditional adsorption methods are limited by the number of active sites on the adsorbent, and one active adsorption site may capture only one or a few uranyl ions through physical/chemical combinations. − In addition, the adsorbed uranyl ions on the adsorbent surface are positively charged and repel more uranyl ions from approaching nearby adsorption sites due to Coulomb repulsion, thereby greatly reducing the number of effective adsorption sites …”

A freestanding, hierarchically porous poly(imine dioxime) membrane enabling selective gold recovery from e‐waste with unprecedented capacity

“…One is to firstly graft acrylonitrile monomer to some host materials (e.g., halloysite nanotubes, 15 resin, 16 biomass, 17 polymer fibers, 18 cellulose, 12 UiO‐66‐AO 14 ) to form polyacrylonitrile (PAN) modified composites, followed by the subsequent chemical transformation of nitrile groups with hydroxylamine into amidoxime groups; while the expensive equipment is usually needed, especially for radiation‐induced graft polymerization (RIGP) and atom transfer radical polymerization (ATRP) routes 13,18 . The other is to fabricate poly(amidoxime) precursor solution beforehand and then mixed with polymer (e.g., poly(acrylamide), 13 polyvinylidene fluoride 19 ) membrane, porous substrates (e.g., montmorillonite, 20 graphene oxide 21 ) or chemically cross‐linked with glutaraldehyde/Zn 2+ to construct poly(amidoxime)‐modified composites/porous networks 22 . The two‐/multi‐step strategies mentioned above basically require complex operation processes and thus are unsuitable for the cost‐effectively scalable fabrication.…”