Ultra-stable 3D pyridinium salt-based polymeric network nanotrap for selective 99TcO4-/ReO4- capture via hydrophobic and steric engineering

Construction of a Porous Zwitterionic Polyimidazole Resin for the Elimination of Technetium in Acidic Environments

Due to the complex type of coexisting ions, remarkable acidity, and high radioactivity, efficient and sustainable methods for the removal of pertechnetate (99TcO4-) from acidic nuclear waste streams have attracted much attention. Herein, a porous highly polymeric zwitterionic resin (PDVBVIM1.5SO3) was synthesized by installing sulfobetaine zwitterionic units in the polymeric imidazole resin to achieve the purpose of balancing the hydrophilicity and hydrophobicity of the resin structure and improving the reaction kinetics and ion selectivity of the resin at the same time for perrhenate (ReO4-)/99TcO4- removal from acidic solutions. The results demonstrate that PDVBVIM1.5SO3 exhibits fast adsorption kinetics, superior adsorption capacity, and excellent selectivity in the presence of a variety of 1000-fold competing anions. The rapid elimination of ReO4- can be achieved even in 1 mol L-1 HNO3. Importantly, when subject to acid soaking, calcination procedure, and high doses of ionizing radiation, PDVBVIM1.5SO3 maintained its structural integrity and outstanding performance. Additionally, PDVBVIM1.5SO3 displayed outstanding adsorption efficiency toward a simulated Hanford low-activity waste stream with ReO4-. This work demonstrates that achieving a balance between hydrophobicity and hydrophilicity in an exchange resin is of great significance for enhancing the selection and removal of TcO4-/ReO4-, and PDVBVIM1.5SO3 resin could be an excellent acid nuclear waste-adsorbing material candidate.

Efficient Capture of ReO4 - from Water by Imidazolium-Based Cationic Polymeric Nanotraps

Rhenium represents an irreplaceable metal resource, which finds extensive applications in diverse fields, particularly in the aerospace and petrochemical industry. However, its remarkably low natural abundance and the lack of independent ore deposits pose significant challenges to its extraction and recovery processes. In this study, we present the highly efficient adsorption of perrhenate by a cationic polymeric nanotrap material, namely CPN-3VIm. The maximum adsorption capacity of CPN-3VIm-Cl for ReO4 - attains an impressive value of 1220 mg ⋅ g-1. Notably, even in the low-concentration ReO4 - solution of 8.5 ppm, the removal rate could still exceed 99 %. The recycling performance of CPN-3VIm-Cl also shows exceptional results, with both ReO4 - removal and recovery rates surpassing 90 % throughout five adsorption-desorption cycles. Furthermore, CPN-3VIm-Cl exhibits nearly 100 % extraction efficiency for ReO4 - within a broad pH range of 4-10 and demonstrates remarkable structural stability under extreme conditions, such as 3 M sulfuric acid or 3 M nitric acid. Additionally, a comprehensive investigation into the interaction mechanism between CPN-3VIm-Cl and perrhenate was carried out using SEM-EDS mapping, Raman, FT-IR, and XPS analysis.

Clearance of Protein-Bound Uremic Toxins Using Anion Nanotraps with Record High Uptake

Traditional hemodialysis often fails to remove protein-bound uremic toxins (PBUTs) like p-cresyl sulfate (pCS) and indoxyl sulfate (IS) due to their strong binding to human serum albumin, which is linked to adverse cardiovascular outcomes. Herein, a class of cationic polymeric networks, denoted as CPN-X6-CPN-X9, are reported for the efficient removal of PBUTs. The abundant imidazole-based nanotraps in these cationic polymeric networks confer a highly positive charge density, resulting in CPN-X7 achieving a maximum sorption capacity of 1000.8 mg/g for pCS and CPN-X6 offering a maximum sorption capacity of 1028.4 mg/g for IS, surpassing all previously reported sorbents. Furthermore, CPN-X9, which is relatively hydrophobic, exhibits remarkable selectivity in competitive experiments involving large amount of chloride ions and serum albumin, attaining removal rates of up to 74% for pCS and 93% for IS in the recycling in vitro dialysis mode. Meanwhile, CPN-X9 demonstrates excellent recyclability over five cycles, and the cationic polymeric network materials exhibit satisfactory hemocompatibility. The sorption mechanism of the anion exchange process is fully elucidated and verified by density functional theory (DFT) calculations. This study provides valuable insights into enhancing the removal efficiency of PBUTs and presents broad prospects in the field of clinical blood purification.

Fabricating Porous Alkali-Resistant Resin for Segregation of Perrhenate/Pertechnetate Anions from Wastewater

The elimination of the β-emitting pertechnetate ion (99TcO4-) from highly alkaline tank waste poses a daunting challenge that is of great significance for nuclear safety and environmental protection. Herein, we report a strategy to fabricate an alkaline-stable porous resin (PANPEI-MeCl) that features hyperbranched quaternary amine groups grafted on the surface and confined within the pores of a superhydrophobic polymer matrix synthesized by a one-pot method, exhibiting a clear superiority both in adsorption kinetics and efficiency compared with available commercial anion-exchange resins applying to 99TcO4- capture. Notably, the alkaline stability of the resin can be improved by manipulating the length of side chain alkyl groups, and it shows ultrahigh structural integrity and prominent performance toward acid/alkaline soaking, high-temperature calcination procedures, and high doses of ionizing radiation. Encouraged by its excellent peculiarity, PANPEI-MeCl can continuously capture most of the ReO4- from the simulated radioactive waste by using a sequential injection automatic separation system.

Efficient removal of perrhenate/pertechnetate by a pyridinium-based porous polymer

The extraction of 99TcO4- from radioactive effluents is extremely crucial for the purposes of nuclear disposal and environmental remediation. Herein, utilizing a facile and low-cost synthesis method, we report a pyridinium-based cationic polymer network, CPP-Cl, with impressive adsorption performance and ultrafast adsorption kinetics towards ReO4-. The structure featuring highly density of charged pyridinium units was synthesized, making it an effective adsorbent for capturing ReO4-. The material showed fast ReO4- adsorption kinetics reaching adsorption equilibrium within 30 s, an excellent capture capability of 1069.7 mg/g, and exceptional separation efficiency of 94.3% for removing 1000 ppm ReO4-. Furthermore, it possessed excellent reusability in multiple sorption/desorption trials and good uptake capacity within a widely ranging pH values. It is noteworthy that the extraction efficiency of CPP-Cl for ReO4- from simulated nuclear waste can be up to 94.2%. The favorable performance of the material in multiple tests revealed that CPP-Cl has tremendous potential as a high-efficiency sorbent for capturing 99TcO4-/ReO4- in complex nuclear associated environmental systems.

Advanced Porous Materials as Designer Platforms for Sequestering Radionuclide Pertechnetate

Technetium-99 (99Tc), predominantly present as pertechnetate (99TcO4 -), is a challenging contaminant in nuclear waste from artificial nuclear fission. The selective removal of 99TcO4 - from nuclear waste and contaminated groundwater is complex due to (i) the acidic and intricate nature of high-level liquid wastes; (ii) the highly alkaline environment in low-activity level tank wastes, such as those at Hanford, and in high-level wastes at locations like Savannah River; and (iii) the potential for 99TcO4 - to leak into groundwater, risking severe water pollution due to its high mobility. This Review focuses on recent developments in advanced porous materials, including metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and their amorphous counterparts, porous organic polymers (POPs). These materials have demonstrated exceptional effectiveness in adsorbing 99TcO4 - and similar oxyanions. We comprehensively review the adsorption mechanisms of these anions with the adsorbents, employing macroscopic batch/column experiments, microscopic spectroscopic analyses, and theoretical calculations. In conclusion, we present our perspectives on potential future research directions, aiming to overcome current challenges and explore new opportunities in this area. Our goal is to encourage further research into the development of advanced porous materials for efficient 99TcO4 - management.

Synthesis and performance of guanidinium-based cationic organic polymer for the efficient removal of TcO4-/ReO4. JOURNAL OF HAZARDOUS MATERIALS 2024;466:133602. [PMID: 38286051 DOI: 10.1016/j.jhazmat.2024.133602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Cationic organic polymers have found relatively extensive utility for TcO4-/ReO4- removal, but the harsh preparation conditions constrain their practical application. The bifunctional guanidinium-based cationic organic polymer (GBCOP) was successfully and facilely synthesized in benign conditions within 1 h. Batch experiments showed that GBCOP exhibited rapid removal kinetics (1 min, >98.0%) and a substantial removal capacity of 536.8 mg/g for ReO4-. Even in 1000-fold co-existing NO3- anions, the removal efficiency of GBCOP for ReO4- was 74.0%, indicating its good selectivity. Moreover, GBCOP had high removal efficiencies for ReO4- across a wide pH (3.0-10.0) range and presented remarkable stability under the conditions of strong acid and base. GBCOP could be reused four times while removing 80.8% ReO4- from simulated Hanford wastewater. SEM and XPS results revealed that the mechanism of ReO4- removal involved Cl- ion exchange within the channels of GBCOP. Theoretical calculation results supported that existing the strong electrostatic interaction between guanidinium and ReO4-. This dual-function GBCOP material is cost-effective and holds significant potential for large-scale preparation, making it a promising solution for TcO4- removal from nuclear wastewater.

Post-Modification of a Robust Covalent Organic Framework for Efficient Sequestration of 99 TcO4 - /ReO4. Chemistry 2023;29:e202302168. [PMID: 37534580 DOI: 10.1002/chem.202302168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Nuclear industry spent fuel reprocessing and some radioactive contamination sites often involve high acidity and salinity environments. Currently developed and reported sorbents in 99 TcO4 - sequestration from the nuclear waste are unstable and show low adsorption efficiency in harsh conditions. To address this issue, we developed a post-synthetic modification strategy by grafting imidazole-based ionic liquids (ILs) onto the backbone of covalent organic framework (COF) via vinyl polymerization. The resultant COF-polyILs sorbent exhibits fast adsorption kinetics (<5 min) and good sorption capacity (388 mg g-1 ) for ReO4 - (a nonradioactive surrogate of 99 TcO4 - ). Outstandingly, COF-polyILs composite shows superior ReO4 - removal even under highly acidic conditions and in the presence of excess competing ions of Hanford low-level radioactive waste stream, benefiting from the stable covalent bonds between the COF and polyILs, mass of imidazole rings, and hydrophobic pores in COF.