Removal of some radionuclides from contaminated solution using natural clay: bentonite

Recent trends in the phytoremediation of radionuclide contamination of soil by cesium and strontium: Sources, mechanisms and methods: A comprehensive review

This comprehensive review examines recent trends in phytoremediation strategies to address soil radionuclide contamination by cesium (Cs) and strontium (Sr). Radionuclide contamination, resulting from natural processes and nuclear-related activities such as accidents and the operation of nuclear facilities, poses significant risks to the environment and human health. Cs and Sr, prominent radionuclides involved in nuclear accidents, exhibit chemical properties that contribute to their toxicity, including easy uptake, high solubility, and long half-lives. Phytoremediation is emerging as a promising and environmentally friendly approach to mitigate radionuclide contamination by exploiting the ability of plants to extract toxic elements from soil and water. This review focuses specifically on the removal of 90Sr and 137Cs, addressing their health risks and environmental implications. Understanding the mechanisms governing plant uptake of radionuclides is critical and is influenced by factors such as plant species, soil texture, and physicochemical properties. Phytoremediation not only addresses immediate contamination challenges but also provides long-term benefits for ecosystem restoration and sustainable development. By improving soil health, biodiversity, and ecosystem resilience, phytoremediation is in line with global sustainability goals and environmental protection initiatives. This review aims to provide insights into effective strategies for mitigating environmental hazards associated with radionuclide contamination and to highlight the importance of phytoremediation in environmental remediation efforts.

Recent advances in clay minerals for groundwater pollution control and remediation

Clay minerals are abundant on Earth and have been crucial to the advancement of human civilization. The ability of clay minerals to absorb chemicals is frequently utilized to remove hazardous compounds from aquatic environments. Moreover, clay-based adsorbent products are both environmentally acceptable and affordable. This study provides an overview of advances in clay minerals in the field of groundwater remediation and related predictions. The existing literature was examined using data and information aggregation approaches. Keyword clustering analysis of the relevant literature revealed that clay minerals are associated with groundwater utilization and soil pollution remediation. Principal component analysis was used to assess the relationships among clay mineral modification methods, pollutant properties, and the Langmuir adsorption capacity (Qmax). The results demonstrated that pollutant properties affect the Qmax of pollutants adsorbed by clay minerals. Systematic cluster analysis was utilized to classify the collected data and investigate the relationships. The pollution adsorption mechanism of the unique structure of clay minerals was investigated based on the characterization results. Modified clay minerals exhibited changes in surface functional groups, internal structure, and pHpzc. This review provides a summary of recent clay-based materials and their applications in groundwater remediation, as well as discussions of their challenges and future prospects.

Open-framework hybrid zinc/tin selenide as an ultrafast adsorbent for Cs+, Ba2+, Co2+, and Ni2

Efficient adsorption of radioactive ¹³⁷Cs⁺ and ⁶⁰Co²⁺ and their decay products ¹³⁷Ba²⁺ and ⁶⁰Ni²⁺ bears significance for hazard elimination in case of nuclear emergency, which relies on the adsorption rate enhancement that takes advantages of compositional and structural optimization. Herein, we report a zinc-doped selenidostannate constructed from T2-supertetrahedral clusters, namely K_3.4(CH₃NH₃)_0.45(NH₄)_0.15Zn₂Sn₃Se₁₀·3.4 H₂O (ZnSnSe-1K). The soft Se and micro-porosity synergistically endow this material with a binding affinity to Cs⁺, Ba²⁺, Co²⁺, and Ni²⁺ ions and ultrafast kinetics with R > 97.6% in 2-60 min. In particular, ZnSnSe-1K can remove 99.34% of Cs⁺ in 2 min ⁽K_d^Cs > 1.5 × 10⁵ mL g^-1), contributing to a record rate constant k₂ of 9.240 g mg^-1 min^-1 that surpasses all metal chalcogenide adsorbents. ZnSnSe-1K exhibits good acid/base tolerance (pH = 0-12), and the adsorption capacities at neutral are 253.61 ± 9.15, 108.94 ± 25.32, 45.76 ± 14.19 and 38.49 ± 2.99 mg g^-1 for Cs⁺, Ba²⁺, Co²⁺, and Ni²⁺, respectively. The adsorption performances resist well co-existing cations and anions, and the removal rates can keep above or close to 90% even in sea water. ZnSnSe-1K is employed in continuous column and membrane filtration, both of which shows excellent elimination efficiency (R > 99%) for mixed Cs⁺, Ba²⁺, Co²⁺, and Ni²⁺. Especially, the membrane with an ultrathin (70 µm) ZnSnSe-1K layer can remove 97-100% Cs⁺ in suction filtration with a short contact time of 0.33 s. Combined with the simple synthesis, facile elution and great irradiation resistance, ZnSnSe-1K emerges as a selenide adsorbent candidate for use in environmental remediation especially that involving nuclear waste disposal.

The effect of irradiation on the Cs, Co and Eu-removal from aqueous solutions using Greek minerals

Sorption properties of Greek bentonites and zeolites were investigated in raw form and after irradiation for removal of Cs, Co and Eu from aqueous solutions using 137Cs, 60Co and 152Eu as tracers and γ-spectroscopy. The sorption experiments were undertaken under different conditions (pH, concentration, competitive ions and temperature). The structural changes of the sorbents due to irradiation and metal sorption were examined through XRD, FTIR and SEM/EDS. Sorption isotherms were reproduced by mathematical models and thermodynamic parameters were derived. The results showed that the sorption capacity was slightly affected by irradiation. The environmental compatibility tests proved the safe disposal of the investigated materials.

Peelable Nanocomposite Coatings: "Eco-Friendly" Tools for the Safe Removal of Radiopharmaceutical Spills or Accidental Contamination of Surfaces in General-Purpose Radioisotope Laboratories

Radioactive materials are potentially harmful due to the radiation emitted by radionuclides and the risk of radioactive contamination. Despite strict compliance with safety protocols, contamination with radioactive materials is still possible. This paper describes innovative and inexpensive formulations that can be employed as 'eco-friendly' tools for the safe decontamination of radiopharmaceuticals spills or other accidental radioactive contamination of the surfaces arising from general-purpose radioisotope handling facilities (radiopharmaceutical laboratories, hospitals, research laboratories, etc.). These new peelable nanocomposite coatings are obtained from water-based, non-toxic, polymeric blends containing readily biodegradable components, which do not damage the substrate on which they are applied while also displaying efficient binding and removal of the contaminants from the targeted surfaces. The properties of the film-forming decontamination solutions were assessed using rheological measurements and evaporation rate tests, while the resulting strippable coatings were subjected to Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and tensile tests. Radionuclide decontamination tests were performed on various types of surfaces encountered in radioisotope workspaces (concrete, painted metal, ceramic tiles, linoleum, epoxy resin cover). Thus, it was shown that they possess remarkable properties (thermal and mechanical resistance which permits facile removal through peeling) and that their capacity to entrap and remove beta and alpha particle emitters depends on the constituents of the decontaminating formulation, but more importantly, on the type of surface tested. Except for the cement surface (which was particularly porous), at which the decontamination level ranged between approximately 44% and 89%, for all the other investigated surfaces, a decontamination efficiency ranging from 80.6% to 96.5% was achieved.

High-capacity recovery of Cs+ ions by facilely synthesized layered vanadyl oxalatophosphates with the clear insight into remediation mechanism

Radiocesium remediation is of great significance for the sustainable development of nuclear energy and ecological protection. It is very challenging for the effective recovery of ¹³⁷Cs from aqueous solutions due to its strong radioactivity, solubility and mobility. Herein, the efficient recovery of Cs⁺ ions has been achieved by three layered vanadyl oxalatophosphates, namely (NH₄)₂[(VO)₂(HPO₄)₂C₂O₄]·5 H₂O (NVPC), Na₂[(VO)₂(HPO₄)₂C₂O₄]·2 H₂O (SVPC), and K_2.5[(VO)₂(HPO₄)_1.5(PO₄)_0.5(C₂O₄)]·4.5 H₂O (KVPC). NVPC exhibits the ultra-fast kinetics (within 5 min) and high adsorption capacity for Cs⁺ (q_m^Cs = 471.58 mg/g). It also holds broad pH durability and excellent radiation stability. Impressively, the entry of Cs⁺ can be directly visualized by the single-crystal structural analysis, and thus the underlying mechanism of Cs⁺ capture by NVPC from aqueous solutions has been illuminated at the molecular level. This is a pioneering work in the removal of radioactive ions by metal oxalatophosphate materials which highlights the great potential of metal oxalatophosphates for radionuclide remediation.

Adsorption behaviour of pollutants: Heavy metals, radionuclides, organic pollutants, on clays and their minerals (raw, modified and treated): A review

The increasing anthropogenic pressure results in environmental pollution and thus adversely affects the integrity of ecosystems. Consequently, various methods of removing pollutants from effluents have been developed and used to minimise this negative impact, with adsorption on clay minerals identified as the most promising approach. This review examines the adsorption of heavy metals, radionuclides, and organic pollutants on clays/clay minerals and their composites under diverse conditions and deals with the applications of these materials in the construction of engineering barriers for waste management. Additionally, we discuss the efficiency and mechanisms of pollutant adsorption on clays subjected to various treatments and modifications while describing the beneficial effects of such modification/treatment on adsorption performance, reusability, and in vivo/in vitro toxicity.

Efficient removal of Ba2+, Co2+ and Ni2+ by an ethylammonium-templated indium sulfide ion exchanger

Removal of radioactive ¹³³Ba, ⁶⁰Co and ⁶³Ni and their nonradioactive isotopes through ion exchange method would be highly beneficial for the safe disposal of liquid industrial waste, and it also bears importance for the emergency response to nuclear accident. Herein, we report the employment of an indium sulfide [CH₃CH₂NH₃]₆In₈S₁₅ (InS-2) with exchangeable ethylammonium cations for efficient and selective uptake of Ba²⁺, Co²⁺ and Ni²⁺. The corner-sharing linkage of P1-{In₈S₁₇} clusters in InS-2 endow the layered structure with nanoscale windows, which facilitates both transfer and accommodation of the large hydrated divalent metal ions. This results in ultrafast exchange kinetics (10-20 min) and top-level exchange capacities of 211.73 mg g^-1 for Ba²⁺, 103.57 mg g^-1 for Co²⁺, and 111.78 mg g^-1 for Ni²⁺. Particularly, InS-2 achieves ultrahigh K_d values of 2.3 × 10⁵ mL g^-1 for Ba²⁺, 2.0 × 10⁵ mL g^-1 for Co²⁺ and 1.6 × 10⁵ mL g^-1 for Ni²⁺, corresponding to remarkable removal efficiencies larger than 99.4% (C₀ ~ 6 ppm). InS-2 shows high β and γ irradiation resistance, wide pH durability (pH 3-13 for Ba²⁺, pH 3-11 for Co²⁺ and Ni²⁺), and outstanding selectivity against competitor ions (e.g. Na⁺, K⁺, Mg²⁺, Ca²⁺). The InS-2-filled ion exchange column exhibits a fantastic removal effect (R > 99%) for mixed Ba²⁺, Co²⁺, Ni²⁺, as well as Sr²⁺. The ultralong column-treatment on 20000 BVs of flow reveals an affinity order of Co²⁺ > Ni²⁺ > Ba²⁺ > Sr²⁺ for InS-2, which gives deep insights into the adsorption process and interaction between competitor ions. This excellent uptake of Ba²⁺ (Ra by analogy), Co²⁺ and Ni²⁺ ions by InS-2 highlights the great potential of metal chalcogenides as a type of promising materials for minimizing contamination in complex wastewater.

Highly compressible nanocellulose aerogels with a cellular structure for high-performance adsorption of Cu(II)

Cellulose-based aerogels have considerable potential for various application due to renewable, low cost, and high availability. However, mechanical robustness and functionalization remain major challenges. Here, we synthesized a compressible, recoverable cellulose nanofiber (CNF)/carboxymethyl cellulose (CMC)/branched polyethyleneimine (BPEI) aerogel via electrostatic-modulated interfacial covalent crosslinking and freeze-drying process. The porous BPEI@CNF/CMC aerogel possessed excellent mechanical compression and high-density metal-chelating groups, which exhibited fast adsorption kinetics and high adsorption capacity (452.49 mg g^-1) in static copper adsorption process. Furthermore, BPEI@CNF/CMC aerogels displayed excellent recyclability and could still reach 85% after 10 cycles. The integrated analyses of ATR-FTIR and XPS suggested that the predominant adsorption mechanism included electrostatic interaction, ion-exchange and chelation. This strategy provides a sustainable route to fabricate efficient biomass-based adsorbents for selective copper removal from water.

In situ investigation of water on MXene interfaces

A continuum of water populations can exist in nanoscale layered materials, which impacts transport phenomena relevant for separation, adsorption, and charge storage processes. Quantification and direct interrogation of water structure and organization are important in order to design materials with molecular-level control for emerging energy and water applications. Through combining molecular simulations with ambient-pressure X-ray photoelectron spectroscopy, X-ray diffraction, and diffuse reflectance infrared Fourier transform spectroscopy, we directly probe hydration mechanisms at confined and nonconfined regions in nanolayered transition-metal carbide materials. Hydrophobic (K+) cations decrease water mobility within the confined interlayer and accelerate water removal at nonconfined surfaces. Hydrophilic cations (Li+) increase water mobility within the confined interlayer and decrease water-removal rates at nonconfined surfaces. Solutes, rather than the surface terminating groups, are shown to be more impactful on the kinetics of water adsorption and desorption. Calculations from grand canonical molecular dynamics demonstrate that hydrophilic cations (Li+) actively aid in water adsorption at MXene interfaces. In contrast, hydrophobic cations (K+) weakly interact with water, leading to higher degrees of water ordering (orientation) and faster removal at elevated temperatures.

Ultralight and shapeable nanocellulose/metal-organic framework aerogel with hierarchical cellular architecture for highly efficient adsorption of Cu(II) ions

Water contamination by heavy metal pollutants is a global concern due to detrimental effects on the environment and human health. Regenerable, high-performance heavy metal sorbents are urgently demanded for improved water purification. Herein, we present an elegant strategy of interweaving metal-organic framework (MOF-808-ethylene diamine tetraacetic acid) and TEMPO-oxidized cellulose nanofibers (TCNF) to construct freeways in hybrid aerogels for rapid and efficient transport and capture of heavy metal ions. In this strategy, a postsynthetic ligand exchange approach is applied to introduce ordered and high-density accessible binding sites for metal ions. The prepared aerogels show excellent shapeability, ultralow density less than 0.005 g cm^-3, and high hierarchical porosity of 99.82%. Furthermore, benefiting from the abundant chelating groups and accessible surface areas, these aerogels exhibit outstanding uptake capacity of 300 mg g^-1 and rapid adsorption kinetics of 0.031 mg g^-1 h^-1 for Cu(II) ions, significantly better than conventional TCNF aerogels. The aerogels could be easily regenerated at least five cycles without greatly performance loss. These aerogels could effectively remove diverse heavy metal ions from complicated contaminated water. Thus, this work provides a novel method to synthesize environmental-friendly, regenerable, and high-performance adsorption materials for water remediation.

Cs Adsorption and CsCl Particle Formation Facilitated by Amino Talc-like Clay in Aqueous Solutions at Room Temperature

Amino talc-like clay with an increased number of active sites and dispersion in a colloidal system has been synthesized and used for contaminant adsorption and support for nanoparticle formation. Amino talc-like clays having different number of layers and aminoalkyl ligands were synthesized and their Cs uptake behavior was examined. Cs uptake through Cs adsorption and CsCl particle formation facilitated by amino talc-like clay in a colloidal aqueous solution at room temperature are reported. The amino talc-like clay demonstrated better Cs uptake with a high initial Cs concentration than talc and montmorillonite. This might have been caused by a high concentration of trapped Cs and Cl ions in exfoliated amino clay, which eventually became CsCl particles. The formation of the CsCl particles in the amino clay depended on the clay concentration and ethanol treatment. The exfoliation of the basal sheets of the amino clay as a result of a high salt concentration and the protonation of amine induced by ethanol treatment was shown to be a precondition for CsCl particle formation. These results could promote amino talc-like clay for high-concentration Cs uptake and the green synthesis of Cs-halide particles in an aqueous solution.

Removal of radioactive cesium from contaminated water by whey protein amyloids-carbon hybrid filters

We report on the application of an innovative whey protein amyloids–carbon hybrid filter for the removal and disposal of the long-lived radioactive fission product ¹³⁷Cs from aqueous samples. Test experiments revealed a reduction of ¹³⁷Cs radioactivity by a factor of 340 compared to the initial solution, with an efficiency as high as 99.7%. The adsorption capacity of the membrane was explored by performing several cycles of filtration, indicating a potential retention of more than 115 MBq per gram of filtering material at the applied experimental conditions. These results pave the way for further investigations on the applicability of this filter material to other nuclear fission products.

The efficient removal of the long-lived fission product ¹³⁷Cs from radioactive water by a filter material based on whey protein fibrils and activated carbon.

Wood-inspired nanocellulose aerogel adsorbents with excellent selective pollutants capture, superfast adsorption, and easy regeneration

Heavy metal ions can cause a series of hazards to environment and humans. Herein, we developed a wood-inspired nanocellulose aerogel adsorbent with excellent selective capability, superfast adsorption, and easy regeneration. The premise for the design is that the biomimetic honeycomb architecture and specific covalent bonding networks can provide the adsorbent with structural and mechanical integrity yet superfast removal of target contaminants. The as-obtained adsorbent showed the maximum adsorption capacity for Pb(II), Cu(II), Zn(II), Cd(II), and Mn(II) of 571 mg g^-1, 462 mg g^-1, 361 mg g^-1, 263 mg g^-1, and 208 mg g^-1, respectively. The adsorbent could remove Pb(II) species with super-rapid speed (87% and 100% of its equilibrium uptake in 2 min and 10 min, respectively). Furthermore, the adsorption isotherm and kinetics models were in accord with the Langmuir and pseudo-second-order models, indicating that the adsorption behavior was dominated by monolayer chemisorption. The aerogel adsorbent had better affinity for Pb(II) than other coexisting ions in wastewater and could be regenerated for at least five cycles. Such a wood-inspired aerogel adsorbent holds great potential in the application of contaminant cleaning.

The Uptake of Hazardous Metal Ions into a High-Nuclearity Cluster-Based Compound with Structural Transformation and Proton Conduction

The discovery of novel high-nuclearity oxo-clusters considerably promotes the development of cluster science. We report a high-nuclearity oxo-cluster-based compound with acid/alkali-resistance and radiation stabilities, namely, (H₃O)₇[Cd₇Sb₂₄O₂₄(l-tta)₉(l-Htta)₃(H₂O)₆]·29H₂O (FJSM-CA; l-H₄tta = l-tartaric acid), which features a two-dimensionally anionic layer based on the largest Sb-oxo-clusters with 28-metal-ion-core [Cd₄Sb₂₄O₂₄]. It is challenging to efficiently capture Sr²⁺, Ba²⁺ (analogue of ²²⁶Ra), and [UO₂]²⁺ ions from aqueous solutions due to their high water solubility and environmental mobility, while it is unprecedented that a novel Sb-oxo-cluster-based framework material FJSM-CA can efficiently remove these hazardous ions accompanied with intriguing structural transformations. Especially, it shows fast ion-exchange abilities for Sr²⁺, Ba²⁺, and [UO₂]²⁺ (reaches equilibrium within 2, 10, and 20 min, respectively) and high exchange capacity (121.91 mg/g), removal rate R (96%), and distribution coefficient K_d^U (2.46 × 10⁴ mL/g) for uranium. Moreover, the underlying mechanism is clearly revealed, which is attributed to strong electrostatic interactions between exchanged cations and highly negative-charged frameworks and the strong affinity of (COO)^- groups for these cations. Proton conduction of the pristine and Sr²⁺, Ba²⁺, [UO₂]²⁺-loaded products was investigated. This work highlights the design of new oxo-cluster-based materials for radionuclide remediation and proton conduction performance.

Evaluating the adsorptivity of organo-functionalized silica nanoparticles towards heavy metals: Quantitative comparison and mechanistic insight

Organo-functionalized SiO₂ nanoparticles are regarded as promising adsorbents for capture of heavy metals. However, actual adsorptivity of a specific functional group onto SiO₂ surface is unclear, thus extending a debate on which type of organic group possesses a better affinity toward heavy metals. Herein, surface functionalization of SiO₂ with different groups (i.e., -EDTA (ethylenediamine triacetic acid), -COOH, -SO₃H, -SH and -NH₂) were achieved by a facile silylating reaction. Batch experiments indicated that adsorption capacity of SiO₂ was remarkably improved by surface functionalization. Quantitative analysis manifested that one mole of EDTA grafted onto SiO₂ surface can adsorb 1.51 mol of Pb(II) ions, which was 7.7, 17.1, 28.4 and 50.2-fold larger than those of COOH-, SO₃H-, SH- and NH₂-functionalized SiO₂, respectively. This is first time to evaluate adsorptivity of functionalized SiO₂ on the basis of per effective functional group, which may repair deficiency of conventional assessment method that calculated on the basis of per unit mass. Further, adsorption mechanism of these functionalized SiO₂ were identified and uncovered by experimental and theoretical studies. This work not only develops an efficient adsorbent for heavy metal remediation but also provides a valuable insight for evaluation and design of novel SiO₂-based materials.

Graphene oxide wrapped melamine sponge as an efficient and recoverable adsorbent for Pb(II) removal from fly ash leachate

Lead is one of the most toxic elements, which has been well recognized for its negative effect on the environment and human beings. But, preliminary methods such as chemical precipitation, membrane separation etc. and commonly used adsorbents based on adsorption technology were found to be expensive and inefficient. In this study, we modify the surface of melamine sponge (MS) with polydopamine (PDA) and then coat with glutathione/graphene oxide (GG) as the adsorbent (MS@GG) to removal Pb(II) from aqueous solutions and fly ash leachate. The maximum adsorption capacity of MS@GG was calculated to be 349.7 mg Pb/g GG, and the reaction reached equilibrium in 30 min which were both higher than raw GG material and most previously reported adsorbents due to active sites on the surface of GG, as well as the unique macroporous and hydrophilic structure of MS. Meanwhile, based on its easy separation, by using HCl as the regeneration agent, the materials revealed good reproducibility. In addition, when MS@GG was applied for the removal of Pb(II) in fly ash leachate, the removal efficiency reached up to 99.24%, indicating that the novel MS@GG was the promising candidate adsorbent material for Pb(II) removal.

Thioether-based recyclable metal–organic frameworks for selective and efficient removal of Hg2+ from water

Hg²⁺ is highly toxic and hazardous and widely found in polluted water.

Uptake of 137Cs and 85Sr onto thermally treated forms of bentonite

This study focuses on the structural changes of bentonite upon thermal treatment at various temperatures, i.e. 150, 300 and 600, and their effect on the sorption behaviour for ¹³⁷Cs and ⁸⁵Sr. Thermal treatment caused gradual disappearance of the major peak of montmorillonite (at 15.15 Å) and minimization of calcite as observed by powder x-ray diffraction, in addition thermal gravimetric analysis indicated the occurrence of dehydration and dehydroxylation of the materials upon heating. Sorption experiments were carried out by batch-method and data were expressed in terms of distribution coefficients (K_d). Contact time, solution-solid ratio and radionuclide activity concentration were investigated in order to determine the optimal conditions and speculate the mechanism of the uptake. Sorption data revealed that the heated forms had lower selectivity for ¹³⁷Cs than the original bentonite, while B-150 and B-300 were the best sorbents when ¹³⁷Cs presents in salt media. In either case, ion exchange process of ¹³⁷Cs with the crystal lattice cations (i.e. Ca²⁺ and Mg²⁺) was the governing mechanism. Contrarily, bentonite heated forms are recommended sorbents for ⁸⁵Sr, especially B-600. The outperformance of thermally treated bentonites reflected chemical bonding reaction with the surface OH groups as well as precipitation of Sr(OH)₂.

A versatile MOF-based trap for heavy metal ion capture and dispersion

Current technologies for removing heavy metal ions are typically metal ion specific. Herein we report the development of a broad-spectrum heavy metal ion trap by incorporation of ethylenediaminetetraacetic acid into a robust metal-organic framework. The capture experiments for a total of 22 heavy metal ions, covering hard, soft, and borderline Lewis metal ions, show that the trap is very effective, with removal efficiencies of >99% for single-component adsorption, multi-component adsorption, or in breakthrough processes. The material can also serve as a host for metal ion loading with arbitrary selections of metal ion amounts/types with a controllable uptake ratio to prepare well-dispersed single or multiple metal catalysts. This is supported by the excellent performance of the prepared Pd²⁺-loaded composite toward the Suzuki coupling reaction. This work proposes a versatile heavy metal ion trap that may find applications in the fields of separation and catalysis.

Improving barium ion adsorption on two-dimensional titanium carbide by surface modification

To capture radioactive barium from wastewater, the Ti₃C₂T_x material was modified by activation treatment and it exhibited high adsorption ability for removal of Ba²⁺ from aqueous solution.

An assessment of strontium sorption onto bentonite buffer material in waste repository

In the present study, changes occurring in sorption characteristics of a representative bentonite (WIn-BT) exposed to SrCl₂ (0.001-0.1 M) under the pH range of 1-13 were investigated. Such interaction revealed a significant variation in surface charge density and binding energy of ions with respect to bentonite, and alteration in their physicochemical properties viz., specific surface area, cation exchange capacity, thermal and mechanical behaviour were observed. The distribution coefficients (k _d) calculated for sorption onto virgin (UCBT) and contaminated bentonite (CBT) indicated a greater influence of mineralogical changes occurred with variance of pH and strontium concentration. Notably, the sorption mechanism clearly elucidates the effect of structural negative charge and existence of anionic metal species onto CBT, and depicted the reason behind significant k _d values at highly acidic and alkaline pH. The maximum k _d of UCBT and CBT_{(0.001M SrCl2)} were 8.99 and 2.92 L/kg, respectively, at the soil pH 8.5; whereas it was 2.37 and 1.23 L/kg at pH 1 for the CBT_{(0.1M SrCl2)} and CBT_{(0.01M SrCl2)}, respectively. The findings of this study can be useful to identify the physicochemical parameters of candidate buffer material and sorption reversibility in waste repository.

Radioactive Barium Ion Trap Based on Metal-Organic Framework for Efficient and Irreversible Removal of Barium from Nuclear Wastewater

Highly efficient and irreversible capture of radioactive barium from aqueous media remains a serious task for nuclear waste disposal and environmental protection. To address this task, here we propose a concept of barium ion trap based on metal-organic framework (MOF) with a strong barium-chelating group (sulfate and sulfonic acid group) in the pore structures of MOFs. The functionalized MOF-based ion traps can remove >90% of the barium within the first 5 min, and the removal efficiency reaches 99% after equilibrium. Remarkably, the sulfate-group-functionalized ion trap demonstrates a high barium uptake capacity of 131.1 mg g(-1), which surpasses most of the reported sorbents and can selectively capture barium from nuclear wastewater, whereas the sulfonic-acid-group-functionalized ion trap exhibits ultrafast kinetics with a kinetic rate constant k2 of 27.77 g mg(-1) min(-1), which is 1-3 orders of magnitude higher than existing sorbents. Both of the two MOF-based ion traps can capture barium irreversibly. Our work proposes a new strategy to design barium adsorbent materials and provides a new perspective for removing radioactive barium and other radionuclides from nuclear wastewater for environment remediation. Besides, the concrete mechanisms of barium-sorbent interactions are also demonstrated in this contribution.

Reinforced silica monoliths functionalised with metal hexacyanoferrates for cesium decontamination: a combination of a one-pot procedure and skeleton calcination

Procedure describes the synthesis of silica monoliths functionalised with metal hexacyanoferrate (MHCF) using a high internal phase emulsion template. The materials exhibit excellent Cs ion sorption properties.

Influence of adsorption parameters on cesium uptake from aqueous solutions- a brief review

Due to rapid population growth, technological advancement and industrial revolution, the rate of generated waste effluents has become a grave concern.

Strontium selectivity in sodium nonatitanate Na ₄Ti₉O₂₀·xH₂O

We study the extraction of strontium by sodium nonatitanate powder from nitrate strontium and acetate sodium mixture. Experiments show that adsorption is quantitative. The excess Gibbs free energy has been modeled by various models (ideal, 2D Coulomb, regular solution model) for the solid phase. We find that the free energy of the solid phase is controlled by short-range interactions rather than long-ranged Coulombic forces. The selectivity is the consequence of a competition between the liquid and solid phases: both phases prefer strontium rather than sodium but the solid contribution is predominant.