Ultra-High Performance of Hyper-Crosslinked Phosphate-Based Polymer for Uranium and Rare Earth Element Adsorption in Aqueous Solution

Immobilization of controlled Pu:Am ratio on actinide-specific affinity monolith support developed in capillary and coupled to inductively coupled plasma mass spectrometry

The objective of this work was to develop an actinide-specific monolithic support in capillary designed to immobilize precise Pu:Am ratios and its coupling to inductively coupled plasma mass spectrometry (ICP-MS) for immobilized metal affinity chromatography applications. This format offers many advantages, such as reducing the sample amount and waste production, which are of prime importance when dealing with highly active radioelements. Four organic phosphorylated-based monoliths were synthesized in situ through UV photo-polymerization in capillary and characterized. The capillary coupling to ICP-MS was set up in conventional laboratory using Th and Sm as chemical analogues of Pu and Am. A dedicated method was developed to quantify online Th and Sm amounts immobilized on the monolithic capillaries, allowing to select the best monolith candidate poly(BMEP-co-EDMA)adp. By precisely adjusting the elemental composition in the loading solutions and applying the developed quantification method, the controlled immobilization of several Th:Sm molar ratios onto the monolith was successful. Finally, the capillary ICP-MS coupling was transposed in a glove box and by applying the strategy developed to design the monolithic support using Th and Sm, the immobilization of a 10.5 ± 0.2 (RSD = 2.3%, n = 3) Pu:Am molar ratio reflecting Pu ageing over 48 years was achieved in a controlled manner on poly(BMEP-co-EDMA)adp. Hence, the new affinity capillary monolithic support was validated, with only hundred nanograms or less of engaged radioelements and can be further exploited to precisely determine differential interactions of Pu and Am with targeted biomolecules in order to better anticipate the effect of Am on Pu biodistribution.

Polymeric Materials for Rare Earth Elements Recovery

Rare earth elements (REEs) play indispensable roles in various advanced technologies, from electronics to renewable energy. However, the heavy global REEs supply and the environmental impact of traditional mining practices have spurred the search for sustainable REEs recovery methods. Polymeric materials have emerged as promising candidates due to their selective adsorption capabilities, versatility, scalability, and regenerability. This paper provides an extensive overview of polymeric materials for REEs recovery, including polymeric resins, polymer membranes, cross-linked polymer networks, and nanocomposite polymers. Each category is examined for its advantages, challenges, and notable developments. Furthermore, we highlight the potential of polymeric materials to contribute to eco-friendly and efficient REEs recovery, while acknowledging the need to address challenges such as selectivity, stability, and scalability. The research in this field actively seeks innovative solutions to reduce reliance on hazardous chemicals and minimize waste generation. As the demand for REEs continues to rise, the development of sustainable REEs recovery technologies remains a critical area of investigation, with the collaboration between researchers and industry experts driving progress in this evolving field.

Efficient adsorption of low-concentration uranium from aqueous solutions

The development of nuclear energy has led to the depletion of uranium resources and now presents the challenge of treating radioactive wastewater. Extracting uranium from seawater and nuclear wastewater has been identified as an effective strategy for addressing these issues. However, extracting uranium from nuclear wastewater and seawater is still extremely challenging. In this study, an amidoxime-modified feather keratin aerogel (FK-AO aerogel) was prepared using feather keratin for efficient uranium adsorption. The FK-AO aerogel showed an impressive adsorption capacity of 585.88 mg·g^-1 in an 8 ppm uranium solution, with a calculated maximum adsorption capacity of 990.10 mg·g^-1. Notably, the FK-AO aerogel demonstrated excellent selectivity for U(VI) in simulated seawater that contained coexisting heavy metal ions. In a uranium solution having a salinity of 35 g·L^-1 and a concentration of 0.1-2 ppm, the FK-AO aerogel achieved a uranium removal rate of greater than 90 %, indicating its effectiveness in adsorbing uranium in environments having high salinity and low concentration. This suggests that FK-AO aerogel is an ideal adsorbent for extracting uranium from seawater and nuclear wastewater, and it is also expected that it could be used in industrial applications for extracting uranium from seawater.

Design, Synthesis and Actual Applications of the Polymers Containing Acidic P-OH Fragments: Part 2-Sidechain Phosphorus-Containing Polyacids

Macromolecules containing acidic fragments in side-groups—polyacids—occupy a special place among synthetic polymers. Properties and applications of polyacids are directly related to the chemical structure of macromolecules: the nature of the acidic groups, polymer backbone, and spacers between the main chain and acidic groups. The chemical nature of the phosphorus results in the diversity of acidic >P(O)OH fragments in sidechain phosphorus-containing polyacids (PCPAs) that can be derivatives of phosphoric or phosphinic acids. Sidechain PCPAs have many similarities with other polyacids. However, due to the relatively high acidity of −P(O)(OH)2 fragment, bone and mineral affinity, and biocompatibility, sidechain PCPAs have immense potential for diverse applications. Synthetic approaches to sidechain PCPAs also have their own specifics. All these issues are discussed in the present review.

Bioadsorption of Terbium(III) by Spores of Bacillus subtilis

Wastewater containing low concentrations of rare earth ions not only constitutes a waste of rare earth resources but also threatens the surrounding environment. It is therefore necessary to develop environmentally friendly methods of recovering rare earth ions. The spores produced by Bacillus are resistant to extreme environments and are effective in the bioadsorption of rare earth ions, but their adsorption behaviors and mechanisms are not well understood. In this study, the cells and spores of Bacillus subtilis PS533 and PS4150 were used as biosorbents, and their adsorption of terbium ions was compared under different conditions. The adsorption characteristics of the spores were investigated, as were the possible mechanisms of interaction between the spores and rare earth ions. The results showed that the PS4150 spores had the best adsorption effect on Tb(III), with the removal percentage reaching 95.2%. Based on a computational simulation, SEM observation, XRD, XPS, and FTIR analyses, it was suggested that the adsorption of Tb(III) by the spores conforms to the pseudo−second−order kinetics and the Langmuir adsorption isotherm model. This indicates that the adsorption process mainly consists of chemical adsorption, and that groups such as amino, hydroxyl, methyl, and phosphate, which are found on the surface of the spores, are involved in the bioadsorption process. All of these findings suggest that Bacillus subtilis spores can be used as a potential biosorbent for the recovery of rare earth ions from wastewater.

Novel benzylphosphate-based covalent porous organic polymers for the effective capture of rare earth elements from aqueous solutions

It has been a major challenge to develop stable and cost-effective porous materials that efficiently recover heavy rare earth elements (HREEs) due to ever-increasing demand, low availability and high cost of HREEs. This study presents two novel benzylphosphate-based covalent porous organic polymers (BPOP-1 and BPOP-2) that were prepared by facile one-pot Friedel-Crafts reactions. Various analytical techniques are used to investigate the successful syntheses of BPOP materials and establish their material properties, which include an unusual crystalline nature, large surface area, hierarchical pore structure, and superior chemical stabilities. The BPOPs effectively adsorb, and thus remove HREEs from aqueous media. In particular, BPOP-1 had higher phosphate content and exhibits superior adsorption capacities (Eu³⁺: 289.5; Gd³⁺: 292.7; Tb³⁺: 294.4; Dy³⁺: 301.9 mg/g) than BPOP-2, while BPOP-2 had higher mesoporosity and correspondingly supports faster adsorption kinetics. Remarkably, both BPOP materials exhibit some of the highest HREE adsorption capacities reported to date, the selective capture of Dy³⁺ ions, and excellent cyclic adsorption/desorption properties. We provide a potential adsorption mechanism for Dy³⁺ capture by the BPOP adsorbent. These demonstrate that introducing phosphate functionality into a robust porous polymer backbone with high surface area is a promising strategy for selective HREEs capture from wastewater.

Confinement effect of layered double hydroxide on intercalated pyromellitic acidic anions and highly selective uranium extraction from simulated seawater

The oxygen-rich pyromellitic acidic anions (PMA4-) have been intercalated into MgAl-layered double hydroxide to fabricate the MgAl-PMA-LDH (abbr. PMA-LDH) composite, exhibiting excellent adsorption performance toward uranium (U(VI)). Benefiting from the...

Stalagmites in karst cave inspired construction: lotus root-type adsorbent with porous surface derived from CO2-in-water Pickering emulsion for selective and ultrafast uranium extraction

Simultaneous construction of porous and hollow adsorbent, especially from gas-in-water Pickering emulsion (PE) reactor, is vital for improving mass transfer kinetics and uptake amount. Inspired by the formation process of stalagmites in karst cave, amino and amidoxime bifunctionalized lotus root-type microsphere with porous surface (NH₂@AO-PLRMS) is prepared by the silica nanoparticles (SPs)-stabilized CO₂-in-water Pickering emulsion reactor and subsequent two-step grafting polymerization. The important roles of SPs acting as Pickering emulsifier, surface pore-forming agent, and adjusting internal lotus root structure are confirmed. Lotus root-type pores are dependent on the interface intensity and the permeability for compressed CO₂ bubbles in PE droplets. Benefitting from the lotus root-type structure and abundant affinity sites, the maximum uranium adsorption capacity of NH₂@AO-PLRMS is 1214.5 mg·g^-1 at 298 k, and an ultrafast uptake process can be achieved in the first 30 min. Both thermodynamic and kinetic studies indicate a spontaneous, entropy increased, and exothermic chemisorption process, and the synergies of amidoxime and amino groups can enhance the adsorption selectivity. Remarkably, NH₂@AO-PLRMS displays a high uranium adsorption capacity and desorption efficiency after seven cycles. These findings provide a way to obtain adsorbents with enhanced uranium extraction performance from gas-in-water PE reactor.

Highly Selective Adsorption and Desorption of Charged Molecules in Three-Dimensional Networks of Polydopamine-Modified Carbon Nanotube Sponges

We investigated the selective adsorption and desorption behaviors of charged molecules (calcein, brilliant green, and methylene blue) dissolved in water using polydopamine-modified carbon nanotube (CNT) sponges. Porous CNT sponges (CNTSs) as a scaffold for the selective adsorption and desorption of aqueous molecules were fabricated by using a chemical vapor deposition technique. To improve the hydrophilicity of porous CNTS and to control the adsorption and desorption of aqueous molecules, CNT sidewalls were decorated with a hydrophilic polydopamine layer through noncovalent interactions between CNT sidewalls and polydopamine. After this noncovalent chemical modification, the water contact angle of CNTS was close to 0, and the aqueous solution can rapidly infiltrate the three-dimensional (3D) networks of polydopamine-modified CNTS (Pdop-CNTS). The incorporation of pH-responsive polydopamine in CNTS showed an evident advantage of adsorbing positively charged molecules over a pH range of 10.5-4. In aqueous solutions with pH value of ≤3, Pdop-CNTS selectively adsorbed negatively charged molecules. Aqueous molecules carrying net charges were successfully separated from mixture solutions. Moreover, charged calcein and methylene blue molecules adsorbed on the 3D networks of Pdop-CNTS were selectively desorbed from Pdop-CNTS by tuning the pH value of the desorption solution.

Rapid and selective magnetic separation of uranium in seawater and groundwater using novel phosphoramidate functionalized citrate-Fe3O4@Ag nanoparticles

One-pot magnetic separation of uranium (U) in seawater and groundwater samples has been made possible by synthesizing phosphoramidate functionalized Ag coated citrate-Fe₃O₄ nanoparticles (NPs). The magnetic saturation value of these functionalized NPs is 27.1 emu g^-1. The synergistic extraction mechanism of U(VI) ion by the surface-modified phosphoramidate and citrate molecules make these NPs highly selective towards U(VI). The adsorption kinetics follows a pseudo-second-order model and the adsorption isotherm fits successfully to the Langmuir adsorption model. The functionalized NPs show quantitative extraction efficiency in the pH range of 6.5-8 with a maximum loading capacity (Q_m) of 108.7 mg g^-1. The equilibration time required by these functionalized NPs to attain the Q_m value is 120 s. The recycling of these NPs can be done up to 5-6 times with 1.0 mol L^-1 of Na₂CO₃ or NH₄OH for quantitative extraction of U(VI). These functionalized NPs show high resilience towards large number of naturally abundant metal ions.

A metal-free approach to bipyridinium salt-based conjugated porous polymers with olefin linkages

A metal-free bipyridinium salt-activated Knoevenagel condensation strategy was developed to synthesize olefin-linked conjugated porous polymers with π-extended networks, positively charged skeletons, high stability and antibacterial activity.

Unexpected ultrafast and highly efficient removal of uranium from aqueous solutions by a phosphonic acid and amine functionalized polymer adsorbent

P(DMAA–B2MP) was prepared by solvothermal polymerization and exhibits fast and efficient sorption of uranium(vi) from aqueous solutions.