Selective removal of lanthanides from natural waters, acidic streams and dialysate

Radiation synthesis of chitosan/poly(acrylamide-co-maleic acid) hydrogel for the removal of 152+154Eu (III) ions

Using gamma radiation, a chitosan-poly (acrylamide-co-maleic acid) hydrogel was created by copolymerizing acrylamide and maleic acid onto the surface of chitosan. The shape, thermal stability, and structure of the hydrogel were confirmed by Fourier transform infrared analysis, scanning electron microscopy, thermogravimetric analysis, and differential thermal analysis. The batch adsorption of ^152+154Eu(III) ions from an aqueous solution showed a rapid initial uptake with an equilibrium time of 24 h at pH (∼4). The Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm models were used to study the adsorption equilibrium data. The adsorption behavior of ^152+154Eu(III) ions closely followed the Langmuir isotherm, exhibiting a maximum adsorption capacity of 144.96 mg/g. The adsorption kinetics of ^152+154Eu(III) ions are best described by the pseudo-second order model. The thermodynamic parameters were studied and revealed that the adsorption process was spontaneous, exothermic, and favorable at a lower temperature. 0.1 M HCl and AlCl₃ desorbed ^152+154Eu(III) ions with 97.09% and 88.63%, respectively. Hence, the hydrogel will serve as a starting point for the adsorption of trivalent lanthanide ions in the future.

Graphene oxide modified with carboxymethyl cellulose for high adsorption capacities towards Nd(III) and Ce(III) from aqueous solutions

This work addresses a simple method to functionalize graphene oxide with sodium carboxymethyl cellulose using tetraethyl orthosilicate as a linker for rapid and significant removal of Nd(III) and Ce(III) from aqueous solutions. The prepared composite (GO–CMC) was characterized by different techniques to confirm the modification and adsorption process. The sorption performance of the GO–CMC was evaluated using Nd(III) and Ce(III) as absorbent materials. The experimental results demonstrated that the sorption process was excellently fitted by the pseudo-second-order kinetic model. The adsorption results were also analyzed by different isotherm models. According to the Langmuir isotherm model, the experimental sorption capacities at pH 3.0 was 661.21 and 436.55 mg/g for Nd(III) and Ce(III), respectively. The thermodynamic results indicated that the sorption process of the two examined metal ions was endothermic and spontaneous. The regenerated GO–CMC composite has a similar removal percentage to the original composite. These results confirmed that the prepared composite (GO–CMC) could be used as an effective adsorbent for Nd(III) and Ce(III) from certain multielement solutions.

Novel nano network trigonal prismatic Ba2CoO4-deficient BaCoO3 for high-affinity sorption of radiolanthanide elements of biomedical applications: synthesis and sorption studies

Nano trigonal prismatic Ba₂CoO₄ with hierarchical structure and deficient BaCoO₃ with columnar structure have been prepared at low temperatures (400 [BC4] and 500 [BC5]) °C/3h using green method. X-ray diffraction (XRD) results demonstrate the presence of enriched Ba₂CoO₄ phase at 400 °C and multiphase structures: BaCoO₃, BaCoO_3-δ, and Co₃O₄ with a decrease in the amount of Ba₂CoO₄ at 500 °C. The prepared powders are characterized by a high specific surface area (SSA) values which are reflected to the mode of synthesis that leads to produce materials with massive active sites. The SSA of BC4 is higher than that of BC5 which can be correlated to the difference in the microstructure analysis of BC4 and BC5 as given from scanning electron microscope (SEM) and high-resolution transmission electron microscope (HRTEM) studies. Electron spin resonance (ESR) spectroscopy as an effective method for the characterization of vacancy-rich nanostructures indicates that the presence of oxygen vacancies is related mainly to BaCoO₃, BaCoO_3-δ, and Co₃O₄ phases while the effective oxygen vacancies is in BaCoO₃ and BaCoO_3-δ. The nanocrystalline structures of BC4 and BC5 as novel nano-adsorbents are the first time to be tested. Production of Gd radioisotopes through ^natGd(n,γ)^153,159,161Gd and carrier-free ¹⁶¹Tb through ¹⁶⁰Gd(n,γ,) ¹⁶¹Gd [Formula: see text] ¹⁶¹Tb are achieved at 2nd Egyptian nuclear research reactor (ETRR-2). Preliminary sorption study of Gd radioisotopes (represent the lanthanide elements) shows a promising material for the application in the separation and removal of lanthanide elements. The results demonstrated that the fast interaction and efficient sorption of lanthanides ions are based on the novel synthesized nanomaterial that can be considered for the upscale application in this field.

Extraction of various metal ions by open-chain crown ether bridged diphosphates in supercritical carbon dioxide

Various toxic metal ions were successfully removed from solid matrix into supercritical CO2 (scCO2) by open-chain crown ether bridged diphosphates at 313.15 K and 20 MPa, these diphosphates with different ester side chains and different length of ethylene oxide bridge group are highly soluble in supercritical CO2. The extraction efficiency (E%) of heavy metals is between 55 and 89%. Mulliken charge distribution of ligand’s P=O coordination group was calculated to indicate the stability of metal complex. The ligand structure effects and the rationale for different selectivity were discussed. In addition, binding property of these diphosphates towards the alkaline earth metals was further studied following the same extraction procedures. Alkaline earth metal ions Ca2+, Sr2+ and Ba2+ were extracted with E% at 49–74%, 50–73% and 16–64%, respectively. DFT calculations were performed to investigate the interaction energy of the complexes and the correlation with the E% was discussed.

Exploring functionalized titania for task specific application of efficient separation of trivalent f-block elements

Functionalized titania, obtained by grafting the dipicolinic acid functionality, was explored for task specific application of highly efficient separation of trivalent f-block elements.

Adsorption kinetics, thermodynamics, and isotherm studies for functionalized lanthanide-chelating resins

Conventional ion exchange resins are widely utilized to remove metals from aqueous solutions, but their limited selectivity precludes dilute ion extraction. This research investigated the adsorption performance of ligand-functionalized resins towards rare earth elements (REE). Functionalized resin particles were synthesized by grafting different ligands (diethylenetriaminepentaacetic dianhydride (DTPADA), phosphonoacetic acid (PAA), or N,N-bis(phosphonomethyl)glycine (BPG)) onto pre-aminated polymeric adsorbents (diameter ∼ 0.6 mm). Lanthanide uptake trends were evaluated for the functionalized resins using batch adsorption experiments with a mixture of three REEs (Nd, Gd, and Ho at 0.1-1000 mg/L each). Resin physical-chemical properties were determined by measuring their surface area, ligand concentrations, and acidity constants. The aminated supports contained 4.0 mmol/g primary amines, and ligand densities for the functionalized resins were 0.33 mmol/g (PAA), 0.22 mmol/g (BPG), and 0.42 mmol/g (DTPADA). Kinetic studies revealed that the functionalized resins followed pseudo-second order binding kinetics with rates limited by intraparticle diffusion. Capacity estimates for total REE adsorption based on Langmuir q_Max were 0.12 mg/g (amine; ≈ 0.77 µmol/g), 5.0 mg/g (PAA; ≈ 32.16 µmol/g), 3.0 mg/g (BPG; ≈ 19.30 µmol/g), and 2.9 mg/g (DTPADA; ≈ 18.65 µmol/g). Attaching ligands to the aminated resins greatly improved their REE binding strength and adsorption efficiency.

A critical review on remediation, reuse, and resource recovery from acid mine drainage

Acid mine drainage (AMD) is a global environmental issue. Conventionally, a number of active and passive remediation approaches are applied to treat and manage AMD. Case studies on remediation approaches applied in actual mining sites such as lime neutralization, bioremediation, wetlands and permeable reactive barriers provide an outlook on actual long-term implications of AMD remediation. Hence, in spite of available remediation approaches, AMD treatment remains a challenge. The need for sustainable AMD treatment approaches has led to much focus on water reuse and resource recovery. This review underscores (i) characteristics and implication of AMD, (ii) remediation approaches in mining sites, (iii) alternative treatment technologies for water reuse, and (iv) resource recovery. Specifically, the role of membrane processes and alternative treatment technologies to produce water for reuse from AMD is highlighted. Although membrane processes are favorable for water reuse, they cannot achieve resource recovery, specifically selective valuable metal recovery. The approach of integrated membrane and conventional treatment processes are especially promising for attaining both water reuse and recovery of resources such as sulfuric acid, metals and rare earth elements. Overall, this review provides insights in establishing reuse and resource recovery as the holistic approach towards sustainable AMD treatment. Finally, integrated technologies that deserve in depth future exploration is highlighted.

Lanthanide-Loaded Nanoparticles as Potential Fluorescent and Mass Probes for High-Content Protein Analysis

Multiparametric and high-content protein analysis of single cells or tissues cannot be accomplished with the currently available flow cytometry or imaging techniques utilizing fluorophore-labelled antibodies, because the number of spectrally resolvable fluorochromes is limited. In contrast, mass cytometry can resolve more signals by exploiting lanthanide-tagged antibodies; however, only about 100 metal reporters can be attached to an antibody molecule. This makes the sensitivity of lanthanide-tagged antibodies substantially lower than fluorescent reporters. A new probe that can carry more lanthanide molecules per antibody is a desirable way to enhance the sensitivity needed for the detection of protein with low cellular abundance. Herein, we report on the development of new probes utilizing mesoporous silica nanoparticles (MSNPs) with hydroxyl, amine, or phosphonate functional groups. The phosphonated MSNPs proved to be best at loading lanthanides for up to 1.4 × 10⁶ molecules per particle, and could be loaded with various lanthanide elements (Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, and Lu) at relatively similar molar extents. The modified MSNPs can also load a fluorescent dye, allowing bimodal mass and fluorescence-based detection. We achieved specificity of antibody-conjugated nanoparticles (at 1.4 × 10³ antibodies per nanoparticle) for targeting proteins on the cell surface. The new materials can potentially be used as mass cytometry probes and provide a method for simultaneous monitoring of a large host of factors comprising the tumor microenvironment (e.g., extracellular matrix, cancer cells, and immune cells). These novel probes may also benefit personalized medicine by allowing for high-throughput analysis of multiple proteins in the same specimen.

Selective capture of radionuclides (U, Pu, Th, Am and Co) using functional nanoporous sorbents

This work evaluated sorbent materials created from nanoporous silica self-assembled with monolayer (SAMMS) of hydroxypyridinone derivatives (1,2-HOPO, 3,2-HOPO, 3,4-HOPO), acetamide phosphonate (Ac-Phos), glycine derivatives (IDAA, DE4A, ED3A), and thiol (SH) for capturing of actinides and transition metal cobalt. In filtered seawater doped with competing metals (Cr, Mn, Fe, Co, Cu, Zn, Se, Mo) at levels encountered in environmental or physiological samples, 3,4-HOPO-SAMMS was best at capturing uranium (U(VI)) from pH 2-8, Ac-Phos and 1,2-HOPO-SAMMS sorbents were best at pH < 2. 3,4-HOPO-SAMMS effectively captured thorium (Th(IV)) and plutonium (239Pu(IV)) from pH 2-8, and americium (241Am(III)) from pH 5-8. Capturing cobalt (Co(II)) from filtered river water doped with competing metals (Cu, As, Ag, Cd, Hg, Tl, and Pb) was most effective from pH 5-8 with binding affinity ranged from IDAA > DE4A > ED3A > Ac-Phos > SH on SAMMS. Iminodiacetic acid (IDAA)-SAMMS was also outstanding at capturing Co(II) in ground and seawater. Within 5 min, over 99% of U(VI) and Co(II) in seawater was captured by 3,4-HOPO-SAMMS and IDAA-SAMMS, respectively. These nanoporous materials outperformed the commercially available cation sorbents in binding affinity and adsorption rate. They have great potential for water treatment and recovery of actinides and cobalt from complex matrices.

Sources, behaviour, and environmental and human health risks of high-technology rare earth elements as emerging contaminants

Recent studies show that high-technology rare earth elements (REEs) of anthropogenic origin occur in the environment including in aquatic systems, suggesting REEs are contaminants of emerging concern. However, compared to organic contaminants, there is a lack of comprehensive reviews on the anthropogenic sources, environmental behaviour, and public and ecological health risks of REEs. The current review aims to: (1) identify anthropogenic sources, transfer mechanisms, and environmental behaviour of REEs; (2) highlight the human and ecological health risks of REEs and propose mitigation measures; and (3) identify knowledge gaps and future research directions. Out of the 17 REEs, La, Gd, Ce and Eu are the most studied. The main sources of anthropogenic REE include; medical facilities, petroleum refining, mining and technology industries, fertilizers, livestock feeds, and electronic wastes and recycling plants. REEs are mobilized and transported in the environment by hydrological and wind-driven processes. Ecotoxicological effects include reduced plant growth, function and nutritional quality, genotoxicity and neurotoxicity in animals, trophic bioaccumulation, chronic and acute toxicities in soil organisms. Human exposure to REEs occurs via ingestion of contaminated water and food, inhalation, and direct intake during medical administration. REEs have been detected in human hair, nails, and biofluids. In humans, REEs cause nephrogenic systemic fibrosis and severe damage to nephrological systems associated with Gd-based contrast agents, dysfunctional neurological disorder, fibrotic tissue injury, oxidative stress, pneumoconiosis, cytotoxicity, anti-testicular effects, and male sterility. Barring REEs in medical devices, epidemiological evidence directly linking REEs in the environment to human health conditions remains weak. To minimize health risks, a conceptual framework and possible mitigation measures are highlighted. Future research is needed to better understand sources, environmental behaviour, ecotoxicology, and human epidemiology. Moreover, research on REEs in developing regions, including Africa, is needed given prevailing conditions predisposing humans to health risks (e.g., untreated drinking water).

Kinetic Studies on the Removal of Some Lanthanide Ions from Aqueous Solutions Using Amidoxime-Hydroxamic Acid Polymer

Lanthanide metal ions make distinctive and essential contributions to recent global proficiency. Extraction and reuse of these ions is of immense significance especially when the supply is restricted. In light of sorption technology, poly(amidoxime-hydroxamic) acid sorbents are synthesized and utilized for the removal of various lanthanide ions (La³⁺, Nd³⁺, Sm³⁺, Gd³⁺, and Tb³⁺) from aqueous solutions. The sorption speed of trivalent lanthanides (Ln³⁺) depending on the contact period is studied by a batch equilibrium method. The results reveal fast rates of metal ion uptake with highest percentage being achieved after 15-30 min. The interaction of poly(amidoxime-hydroxamic) acid sorbent with Ln³⁺ ions follows the pseudo-second-order kinetic model with a correlation coefficient R² extremely high and close to unity. Intraparticle diffusion data provide three linear plots indicating that the sorption process is affected by two or more steps, and the intraparticle diffusion rate constants are raised among reduction of ionic radius of the studied lanthanides.

Rare Earth Elements Removal from Water Using Natural Polymers

Adsorption of rare earth metals, Eu (III) and Nd (III) was investigated on a new environmental friendly material, thiourea functionalized cellulose. Before usage, the synthesized material was characterized by Fourrier Transform Infrared spectroscopy and energy dispersive X-ray analysis. The influence of adsorption parameters (adsorbent dosage, time, temperature and initial metal concentration) on adsorption capacity was investigated. Experimental data were fitted by using the pseudo-first-order and pseudo-second-order kinetic models. Simultaneously thermodynamic and equilibrium studies have been carried out using Langmuir, Freundlich and Sips isotherm. Maximum adsorption capacities were reached in 30 minutes at 298 K having the value of 27 mg/g for Eu (III) and 73 mg/g for Nd (III).

Development of a sensor for trivalent iron: AHP fixed on mesoporous silica

Optical sensor for iron(iii) detection via Fe(iii) complexation in the solid phase.

Phosphonic acid: preparation and applications

The phosphonic acid functional group, which is characterized by a phosphorus atom bonded to three oxygen atoms (two hydroxy groups and one P=O double bond) and one carbon atom, is employed for many applications due to its structural analogy with the phosphate moiety or to its coordination or supramolecular properties. Phosphonic acids were used for their bioactive properties (drug, pro-drug), for bone targeting, for the design of supramolecular or hybrid materials, for the functionalization of surfaces, for analytical purposes, for medical imaging or as phosphoantigen. These applications are covering a large panel of research fields including chemistry, biology and physics thus making the synthesis of phosphonic acids a determinant question for numerous research projects. This review gives, first, an overview of the different fields of application of phosphonic acids that are illustrated with studies mainly selected over the last 20 years. Further, this review reports the different methods that can be used for the synthesis of phosphonic acids from dialkyl or diaryl phosphonate, from dichlorophosphine or dichlorophosphine oxide, from phosphonodiamide, or by oxidation of phosphinic acid. Direct methods that make use of phosphorous acid (H3PO3) and that produce a phosphonic acid functional group simultaneously to the formation of the P-C bond, are also surveyed. Among all these methods, the dealkylation of dialkyl phosphonates under either acidic conditions (HCl) or using the McKenna procedure (a two-step reaction that makes use of bromotrimethylsilane followed by methanolysis) constitute the best methods to prepare phosphonic acids.

Removal of gadolinium-based contrast agents: adsorption on activated carbon

Three carbon samples were employed in this work, including commercial (1690 m² g^-1), activated carbon prepared from guava seeds (637 m² g^-1), and activated carbon prepared from avocado kernel (1068 m² g^-1), to study the adsorption of the following gadolinium-based contrast agents (GBCAs): gadoterate meglumine Dotarem®, gadopentetate dimeglumine Magnevist®, and gadoxetate disodium Primovist®. The activation conditions with H₃PO₄ were optimized using a Taguchi methodology to obtain mesoporous materials. The best removal efficiency by square meter in a batch system in aqueous solution and model urine was achieved by avocado kernel carbon, in which mesoporosity prevails over microporosity. The kinetic adsorption curves were described by a pseudo-second-order equation, and the adsorption isotherms in the concentration range 0.5-6 mM fit the Freundlich equation. The chemical characterization of the surfaces shows that materials with a greater amount of phenolic functional groups adsorb the GBCA better. Adsorption strongly depends on the pH due to the combination of the following factors: contrast agent protonated forms and carbon surface charge. The tested carbon samples were able to adsorb 70-90% of GBCA in aqueous solution and less in model urine. This research proposes a method for the elimination of GBCA from patient urine before its discharge into wastewater.

Organic layer formation and sorption of U(vi) on acetamide diethylphosphonate-functionalized mesoporous silica

Solid-state NMR is used to connect the molecular structure of acetamide phosphonate-functionalized mesoporous silica with its macroscopic U(vi) extraction properties.

Separation of actinides from spent nuclear fuel: A review

This review summarises the methods currently available to extract radioactive actinide elements from solutions of spent nuclear fuel. This separation of actinides reduces the hazards associated with spent nuclear fuel, such as its radiotoxicity, volume and the amount of time required for its' radioactivity to return to naturally occurring levels. Separation of actinides from environmental water systems is also briefly discussed. The actinide elements typically found in spent nuclear fuel include uranium, plutonium and the minor actinides (americium, neptunium and curium). Separation methods for uranium and plutonium are reasonably well established. On the other hand separation of the minor actinides from lanthanide fission products also present in spent nuclear fuel is an ongoing challenge and an area of active research. Several separation methods for selective removal of these actinides from spent nuclear fuel will be described. These separation methods include solvent extraction, which is the most commonly used method for radiochemical separations, as well as the less developed but promising use of adsorption and ion-exchange materials.

Functionalized magnetic mesoporous silica nanoparticles for U removal from low and high pH groundwater

U(VI) species display limited adsorption onto sediment minerals and synthetic sorbents in pH <4 or pH >8 groundwater. In this work, magnetic mesoporous silica nanoparticles (MMSNs) with magnetite nanoparticle cores were functionalized with various organic molecules using post-synthetic methods. The functionalized MMSNs were characterized using N2 adsorption-desorption isotherms, thermogravimetric analysis (TGA), transmission electron microscopy (TEM), (13)C cross polarization and magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectroscopy, and powder X-ray diffraction (XRD), which indicated that mesoporous silica (MCM-41) particles of 100-200nm formed around a core of magnetic iron oxide, and the functional groups were primarily grafted into the mesopores of ∼3.0nm in size. The functionalized MMSNs were effective for U removal from pH 3.5 and 9.6 artificial groundwater (AGW). Functionalized MMSNs removed U from the pH 3.5 AGW by as much as 6 orders of magnitude more than unfunctionalized nanoparticles or silica and had adsorption capacities as high as 38mg/g. They removed U from the pH 9.6 AGW as much as 4 orders of magnitude greater than silica and 2 orders of magnitude greater than the unfunctionalized nanoparticles with adsorption capacities as high as 133mg/g. These results provide an applied solution for treating U contamination that occurs at extreme pH environments and a scientific foundation for solving critical industrial issues related to environmental stewardship and nuclear power production.

Phosphonate-functionalized polystyrene microspheres with controlled zeta potential for efficient uranium sorption

A new method has been developed for effective uranium(vi) sorption from aqueous solution through phosphonate-functionalized polystyrene microspheres with controlled zeta potentials.

The impact of structural variation in simple lanthanide binding peptides

A series of di-, tri- and tetra-peptides were synthesised using l- and d-glutamic acid in order to determine the effects of peptide length and stereochemistry on lanthanide binding affinity.

Functionalization of mesoporous materials for lanthanide and actinide extraction

Recent advances in the field of functionalized mesoporous solid-phase sorbents designed for rare earth element and actinide separation/concentration could provide answers to limitations occurring in the industrial separation processes of these critical elements.

Translocation of uranium from water to foodstuff while cooking

The present work report the unusual uranium uptake by foodstuff, especially those rich in carbohydrates like rice when they are cooked in water, contaminated with uranium. The major staple diet in South Asia, rice, was chosen to study its interaction with UO2(2+), the active uranium species in water, using inductively coupled plasma mass spectrometry. Highest uptake limit was checked by cooking rice at very high uranium concentration and it was found to be good scavenger of uranium. To gain insight into the mechanism of uptake, direct interaction of UO2(2+) with monosaccharides was also studied, using electrospray ionization mass spectrometry taking mannose as a model. The studies have been done with dissolved uranium salt, uranyl nitrate hexahydrate (UO2(NO3)2·6H2O), as well as the leachate of a stable oxide of uranium, UO2(s), both of which exist as UO2(2+) in water. Among the eight different rice varieties investigated, Karnataka Ponni showed the maximum uranium uptake whereas unpolished Basmati rice showed the minimum. Interaction with other foodstuffs (potato, carrot, peas, kidney beans and lentils) with and without NaCl affected the extent of chemical interaction but was not consistent with the carbohydrate content. Uranium interaction with D-mannose monitored through ESI-MS, under optimized instrumental parameters, identified the peaks corresponding to uranyl adduct with mannose monomer, dimer and trimer and the species were confirmed by MS/MS studies. The product ion mass spectra showed peaks illustrating water loss from the parent ion as the collision energy was increased, an evidence for the strong interaction of uranium with mannose. This study would constitute the essential background for understanding interaction of uranium with various foods. Extension of this work would involve identification of foodstuff as green heavy metal scavengers.

Rare Elements Electrochemistry: The Development of a Novel Electrochemical Sensor for the Rapid Detection of Europium in Environmental Samples Using Gold Electrode Modified with 2-pyridinol-1-oxide

This work presents for the first time the electrochemical determination of europium using cyclic voltammetry at gold electrodes modified with 2-pyridinol-1-oxide. A well-defined oxidation peak was observed in cyclic voltammetry as a result of the oxidation of the europium at ∼1100 mV in phosphate buffer at pH 7.0. The peak current increased linearly with the increase of concentration of the europium over the range from 1 to 80 μM and detection limit (based on 3-sigma) and quantification were found to be 0.3 and 0.549 μM, respectively. The analytical utility of the developed protocol was evaluated by performing the detection of the europium in river water. Europium is also linear over the concentration range 10 to 150 μM. (I(p)/μA = 0.7239x + 108.19, R(2) = 0.9981 and n = 9) with a detection limit of 6.5 μM (based on 3-sigma). This simple and effective protocol exhibited good sensitivity, precision and reliability towards the detected analyte.