Analysis of technetium immobilization and its molecular retention mechanisms by Fe(II)-Al(III)-Cl layered double hydroxide

Mayordomo, Natalia; Rodríguez, Diana M.; Roßberg, André; Foerstendorf, Harald; Heim, Karsten; Brendler, Vinzenz; Müller, K.

doi:10.1016/j.cej.2020.127265

Cited by 31 publications

(12 citation statements)

References 58 publications

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“…LDHs are formed by positively charged layers with the weakly bound, charge balancing anion(s) located in the interlayer region that are capable of anion exchange with other negative charged ions of various, but compatible, shapes and sizes from contaminated waste solutions . The incorporation and removal mechanism of aqueous TcO 4 – by LDHs can be attributed to the TcO 4 – adsorption on the outer surface, intercalation by anion exchange, and/or structural transformation or reconstruction. − …”

Section: Effective Sequestration Of 99tcmentioning

confidence: 99%

“…Finally, the authors claimed that controlling the physicochemical conditions during the synthesis and application of LDH materials could play a significant role in altering the uptake capacity of 99 in Fe(II)-Al(III)-Cl LDH as a function of pH, Tc concentration, and ionic strength under aerobic conditions. 36 The synthesis of Fe(II)-Al(III)-Cl LDH was carried out in a glovebox, and the material was characterized by the XRD, Raman, and scanning electron microscopy (SEM) analyses. Over 80% TcO 4 − removal efficiency was achieved from solution <0.1 M NaCl concentration between pH 3.5 and 10.5, as displayed in Figure 1.…”

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confidence: 99%

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Design and Application of Materials for Sequestration and Immobilization of ⁹⁹Tc

Singh

Mahzan

Rashid

et al. 2023

Environ. Sci. Technol.

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99Technetium (99Tc) is a hazardous radionuclide that poses a serious environmental threat. The wide variation and complex chemistries of liquid nuclear waste streams containing 99Tc often create unique, site specific challenges when sequestering and immobilizing the waste in a matrix suitable for long-term storage and disposal. Therefore, an effective management plan for 99Tc containing liquid radioactive wastes (such as storage (tanks) and decommissioned wastes) will likely require a variety of suitable materials/matrixes capable of adapting to and addressing these challenges. In this review, we discuss and highlight the key developments for effective removal and immobilization of 99Tc liquid waste in inorganic waste forms. Specifically, we review the synthesis, characterization, and application of materials for the targeted removal of 99Tc from (simulated) waste solutions under various experimental conditions. These materials include (i) layered double hydroxides (LDHs), (ii) metal–organic frameworks (MOFs), (iii) ion-exchange resins (IERs) as well as cationic organic polymers (COPs), (iv) surface modified natural clay materials (SMCMs), and (v) graphene-based materials (GBMs). Second, we discuss some of the major and recent developments toward 99Tc immobilization in (i) glass, (ii) cement, and (iii) iron mineral waste forms. Finally, we present future challenges that need to be addressed for the design, synthesis, and selection of suitable matrixes for the efficient sequestration and immobilization of 99Tc from targeted wastes. The purpose of this review is to inspire research on the design and application of various suitable materials/matrixes for selective removal of 99Tc present globally in different radioactive wastes and its immobilization in stable/durable waste forms.

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Section: Effective Sequestration Of 99tcmentioning

confidence: 99%

mentioning

confidence: 99%

Design and Application of Materials for Sequestration and Immobilization of ⁹⁹Tc

Singh

Mahzan

Rashid

et al. 2023

Environ. Sci. Technol.

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“…Until now, many different approaches have been developed for TcO 4 – /ReO 4 – removal. ,− Ion exchange and reductive immobilization are the routine methods currently applied in anion removal, , but the development of TcO 4 – /ReO 4 – anion-sorbent materials with high uptake capacity, fast kinetics, and selectivity is still the research hotspot and frontier trend. Specifically, recognition-based anion separation based on supramolecular receptors can provide sorbent materials with better affinities, recyclabilities, and selectivities for their applications under real situations.…”

Section: Introductionmentioning

confidence: 99%

Anion−π Interaction Powered Perrhenate Recognition and Extraction in Aqueous Media

et al. 2023

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Selective anion recognition and extraction in aqueous media is a challenging research topic, and the anion−π interaction is an undetermined solution for the development of anion sorbent materials with better affinity and selectivity. Here, noncovalent anion−π interaction was introduced as the driving force for this purpose. A cage-based 2D cationic metal–organic framework, IPM-21, is featured with porous channels formed by complementary V-shape electron-deficient cavities. This 3D rhombic electron-deficient cavity can bind two anions with the clipped π-acidic surfaces, exhibiting much higher affinity toward ReO4 – due to the strong complementary effect. This cavity was forced to expand its opening size to seamlessly adopt the ReO4 – anion with a large volume. Experimental results found that the binding energy of IPM-21 with ReO4 – is around 2.3 kJ/mol higher than that with ClO4 –. Parts per million levels of the ReO4 – anion in aqueous media can be effectively extracted by IPM-21 with a removal up to 99%, even with mixed competing anions. IPM-21 can be easily recycled and reused by treatment with high concentration aqueous NaClO4. Due to the extremely low interlamellar interaction, the IPM-21 crystal exhibited enhanced ReO4 – extraction performance with the recycling times due to self-exfoliation; as a result, ultrathin IPM-21 nanosheets with large lateral sizes were produced in this process.

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“…Thus, the reduction of Tc(VII) to Tc(IV) is an effective strategy for technetium immobilization. Recently, several Fe(II) minerals have been studied in detail: iron sulfide in the form of pyrite and marcasite 13−15 chukanovite, 16 magnetite, 17,18 or other common systems like layered double hydroxides 19 trigger Tc(VII) reduction and then incorporate, precipitate, or adsorb Tc(IV). Despite the clear relevance of the reduction of Tc(VII) from an environmental and chemical point of view, more than 80 years after the discovery of technetium, its reduction mechanisms in water are not well understood yet.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Exploring the Reduction Mechanism of⁹⁹Tc(VII) in NaClO₄: A Spectro-Electrochemical Approach

et al. 2022

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Technetium (Tc) is an environmentally relevant radioactive contaminant whose migration is limited when Tc(VII) is reduced to Tc(IV). However, its reaction mechanisms are not well understood yet. We have combined electrochemistry, spectroscopy, and microscopy (cyclic voltammetry, rotating disk electrode, X-ray photoelectron spectroscopy, and Raman and scanning electron microscopy) to study Tc(VII) reduction in noncomplexing media: 0.5 mM KTcO 4 in 2 M NaClO 4 in the pH from 2.0 to 10.0. At pH 2.0, Tc(VII) first gains 2.3 ± 0.3 electrons, following Tc(V) rapidly receives 1.3 ± 0.3 electrons yielding Tc(IV). At pH 4.0−10.0, Tc(IV) is directly obtained by transfer of 3.2 ± 0.3 electrons. The reduction of Tc(VII) produced always a black solid identified as Tc(IV) by Raman and XPS. Our results narrow a significant gap in the fundamental knowledge of Tc aqueous chemistry and are important to understand Tc speciation. They provide basic steps on the way from non-complexing to complex media.

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Analysis of technetium immobilization and its molecular retention mechanisms by Fe(II)-Al(III)-Cl layered double hydroxide

Cited by 31 publications

References 58 publications

Design and Application of Materials for Sequestration and Immobilization of ⁹⁹Tc

Design and Application of Materials for Sequestration and Immobilization of ⁹⁹Tc

Anion−π Interaction Powered Perrhenate Recognition and Extraction in Aqueous Media

Exploring the Reduction Mechanism of⁹⁹Tc(VII) in NaClO₄: A Spectro-Electrochemical Approach

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Analysis of technetium immobilization and its molecular retention mechanisms by Fe(II)-Al(III)-Cl layered double hydroxide

Cited by 31 publications

References 58 publications

Design and Application of Materials for Sequestration and Immobilization of 99Tc

Design and Application of Materials for Sequestration and Immobilization of 99Tc

Anion−π Interaction Powered Perrhenate Recognition and Extraction in Aqueous Media

Exploring the Reduction Mechanism of99Tc(VII) in NaClO4: A Spectro-Electrochemical Approach

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Design and Application of Materials for Sequestration and Immobilization of ⁹⁹Tc

Design and Application of Materials for Sequestration and Immobilization of ⁹⁹Tc

Exploring the Reduction Mechanism of⁹⁹Tc(VII) in NaClO₄: A Spectro-Electrochemical Approach