Extraction Of Lanthanides Research Articles

Membrane transport of rare earth metal ions N, N’-bisdioctylphosphorylmethyl-1,4-diaminobutane by the active transport mechanism

The method of membrane extraction for rare earth elements (REE) using the carrier N, N’-bisdioctylphosphorylmethyl-1,4-diaminobutane (DPDA-8) ions, leveraging an active transport mechanism, has been optimized. The distribution of DPDA-8 within the membrane pores was confirmed using scanning electron microscopy (SEM). Both light and heavy REE extractions from a simulated solution using DPDA-8 and trioctylphosphine oxide (TOPO) in 1,2-dichlorobenzene were explored. The influence of feed solution pH, carrier and anion concentration, supported liquid membrane (SLM) type and stability, and cell temperature, among other parameters, were meticulously examined. The results indicate a decrease in permeability with a decrease in feed solution pH attributed to competitive acid transport through the membrane. Additionally, the formation of H-complexes between carriers and perchloric or phosphoric acids was investigated using Fourier Transform Infrared (FTIR) spectroscopy and X-ray diffraction (XRD) techniques. Changes in the stretching bands of amino and phosphine oxide groups in DPDA-8 were monitored and characterized. XRD analysis of the crystal structures of salts DPDA-6·ClO4 and DPDA-12·H2PO4 revealed a two-dimensional layered supramolecular organization with varying anion positions relative to hydrophobic fragments. The DPDA-8 carrier demonstrated significantly higher permeability values compared to TOPO, with differences in permeability exceeding twofold for certain metals. FTIR spectroscopy identified the main coordination centers of DPDA-8 during the liquid–liquid extraction of specific REEs.

Novel nitrogen-rich hydrogel adsorbent for selective extraction of rare earth elements from wastewater

Efficient recovery of rare earth elements (REEs) from wastewater is crucial for advancing resource utilization and environmental protection. Herein, a novel nitrogen-rich hydrogel adsorbent (PEI-ALG@KLN) was synthesized by modifying coated kaolinite-alginate composite hydrogels with polyethylenimine through polyelectrolyte interactions and Schiff’s base reaction. Various characterizations revealed that the high selective adsorption capacity of Ho (155 mg/g) and Nd (125 mg/g) on PEI-ALG@KLN is due to a combination of REEs (Lewis acids) via coordination interactions with nitrogen-containing functional groups (Lewis bases) and electrostatic interactions; its adsorption capacity remains more than 85 % after five adsorption-desorption cycles. In waste NdFeB magnet hydrometallurgical wastewater, the recovery rate of PEI-ALG@KLN for Nd and Dy can reach more than 93 %, whereas that of Fe is only 5.04 %. Machine learning prediction was used to evaluate adsorbent properties via different predictive models, with the random forest (RF) model showing superior predictive accuracy. The order of significance for adsorption capacity was pH > time > initial concentration > electronegativity > ion radius, as indicated by the RF model feature importance analysis and SHapley Additive exPlanations values. These results confirm that PEI-ALG@KLN has considerable potential in the selective extraction of REEs from wastewater.

Efficient extraction of rare earth elements from coal-series kaolin by combining alkali fusion and sulfamic acid leaching

As a solid waste produced by coal mining, the comprehensive utilization of coal-series kaolin is the focus of attention. In this paper, the extraction of rare earth elements (REEs) from coal-series kaolin was carried out by alkali fusion and sulfamic acid leaching. The occurrence modes of REEs in coal-series kaolin was analyzed by means of inductively coupled plasma-mass spectrometry analyse and sequential chemical extraction. The influence of alkali fusion conditions on the leaching of REEs was investigated, and the activation mechanism of alkali fusion was revealed by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and field emission scanning electron microscope (FESEM) analysis. In addition, the effect of key operating parameters on the leaching efficiency of REEs from coal-series kaolin was further investigated. The results show that REEs mainly existed in silicate & aluminosilicate state of coal-series kaolin. The mineral structure was destroyed by alkali fusion, and the leaching efficiency of REEs was increased by 59.08 %. At the sulfamic acid concentration of 0.5 mol/L, H2O2 concentration of 0.2 mol/L, solid to liquid ratio of 1/50, the leaching efficiencies of total rare earth elements, light rare earth elements and heavy rare earth elements were 84.91 %, 88.43 % and 71.03 %, respectively.

A cationic three-dimensional covalent organic framework membrane for nanofiltration of molecules and rare Earth ions

Permanently microporous materials have evolved as focal point of research for tackling issues in separation science and membrane technology. Covalent organic frameworks (COFs) stand out for their distinctive synergy of crystalline nature, uniform channels, and structural diversities. Three-dimensional (3D) COFs, distinguished by angstrom-sized and interconnected channels, hold special promise for separating small targets; however, this potential remains underexplored. Here, we report feasible growth of cationic 3D COF membranes on a flexible polymer substrate for versatile nanofiltration toward both molecules and ions. Through comprehensive performance evaluations, we reveal that the resultant membrane exhibits durable and prominent molecular selectivity to separate fine species with molecular weights above 300 g mol−1 at fast methanol permeation. Lanthanide ions of industrial value also can be harvested by the membrane with rejection rates of up to 91.4%. Together with its nonselectivity to competing ions, our membrane implements efficient extraction of rare earth elements from ion mixtures. These findings illuminate the potential of 3D COFs for liquid separation and offer a solution to building versatile membranes.

New Insights on Y, La, Nd, and Sm Extraction with Bifunctional Ionic Liquid Cyphos IL 104 Incorporated in a Polymer Inclusion Membrane.

In this study, an ionic liquid-based polymer inclusion membrane (IL-PIM) made of (50% polymer-50% CyphosIL104) was used to extract and separate the rare earth elements (REEs) Y, La, Nd, and Sm in chloride solutions. The effect of extraction time and pH was studied to optimize the extraction and separation conditions. The four REEs were effectively extracted at pH 4-5 from both single and mixed metals solutions. However, at pH 2, only Y was extracted. The recovery of the extracted REEs from the loaded PIM was achieved using HNO3 and H2SO4. In the case of La, it was quantitatively back-extracted with H2SO4 after a contact time of 1 h, while up to 4 h was necessary to recover 70% of the extracted Y, Sm, and Nd. Extraction isotherms were studied, and the Freundlich isotherm model was the most adequate to describe the interaction between the PIM and the REEs. Finally, the developed PIM was investigated for the extraction of REEs from mixtures containing other metals, which showed great selectivity for the REEs.

Iron(III) and neodymium co-extraction mechanism with TODGA from chloride medium

In the context of NdFeB magnets recycling, solvent extraction of lanthanides using diglycolamides is promising but their separation from iron(III) remains a challenge. Here, the extraction mechanisms of iron(III) and neodymium by TODGA (N,N,N′,N′-tetraoctyldiglycolamide) were examined in chloride medium. The choice of chloride media was driven by the efficiency of HCl in dissolving NdFeB magnets. Neodymium was chosen as a representative lanthanide to examine the co-extraction mechanism. For the extraction of iron(III), UV–visible and FT-IR spectra provide evidence for the extraction of FeCl4- with the participation of TODGA carbonyl groups. For the extraction with both elements, the solvent extraction study points out that there is co-extraction of neodymium and iron(III). Neodymium(III) extraction percentage increases from 6 to more than 97 % by adding iron(III). From spectroscopic studies (UV–visible, FT-IR) and thermodynamic modelling of extraction data, it is shown that three molecules of TODGA extract neodymium, as for neodymium-only extraction. They also reveal the presence of Fe(III) as FeCl4- anion in the outer sphere of [Nd(TODGA)3]3+. This brings to the conclusion that [Nd(TODGA)3](FeCl4)3 complex is formed in the organic phase. DFT (Density Functional Theory) calculations confirm that FeCl4- can replace Cl- in the outer sphere of [Nd(TODGA)3]3+, in a two-step reaction, with the initial formation of [Nd(TODGA)3]Cl3 followed by the binding of FeCl3 to the outer-sphere chloride ion. These results pave the way to the design of new diglycolamides that are selective towards iron(III) from chloride medium. The complete dissolution solution of NdFeB is represented by a highly acidic medium (a solution of 3 M HCl), whereas the leaching solution (partial dissolution of NdFeB) is represented by a weakly acidic medium (NaCl).

Acute and chronic toxicity of rare earth elements-enriched sediments from a prospective mining area: Effects on life history traits, behavioural and physiological responses of Gammarus fossarum (Crustacea Amphipoda)

Rare earth elements (REE) have an essential role and growing importance in the world's economy. They are attracting interest from society, policymakers, and scientists. The rapidly growing global demand for REE in several strategic industrial and agricultural sectors led many countries to consider the (re)-opening of mining activities for REE extraction. Hence, their increasing use led to the disruption of their biogeochemical cycles with anthropic abnormalities already observed in aquatic ecosystems. Nonetheless, REE remain less studied, and their mechanisms of toxicity actions are not fully understood. As amphipods, Gammarus fossarum represent an important part of the aquatic macroinvertebrate assemblage and are generally used in ecotoxicological studies for their high ecological relevance. However, their use for the study of REE effects has been rather limited so far. The current study aims to assess the potential effects of two naturally REE-enriched sediments (N2 and B4) on G. fossarum. Effects on life history traits, behavioural and physiological responses have been evaluated. Exposing G. fossarum males for 72h to sediments N2 and B4 led to a decrease in haemolymph osmolality and locomotion while an increase in ventilatory activity was observed. Exposing G. fossarum pre-copula pairs with females at the same reproductive stage to the naturally REE-enriched sediments, for one moult cycle duration (∼30 days) showed that sediment B4 led to i) a significant uptake of REE, ii) a significant decrease in the proportion of females with oocytes and iii) a significant reduction in the total number of juveniles. The physicochemical analyses of sediments showed that B4 contains the highest amount of REE with a higher proportion of light REE. The present study gives the first insights into the potential toxicity of REE on G. fossarum as they may have deleterious effects on G. fossarum population's dynamics, which may alter the functioning of aquatic ecosystems.

Critical minerals and rare earth elements in a planetary just transition: An interdisciplinary perspective

While vital for the development of ‘clean’ energy technologies, the extraction and processing of critical minerals and rare earth elements entail a range of overlapping social and environmental harms in local communities across the world. The transition to low-carbon economies invokes a host of multiscalar dilemmas, injustices and trade-offs, notably between the global imperative to reduce greenhouse gas emissions and the local consequences of mineral mining. There are profound barriers to delivering a just energy transition at a planetary scale given the reliance of green technologies upon socio-environmentally harmful extractive practices across critical mineral supply chains. Adopting an interdisciplinary lens and drawing from a set of international case studies, we critically examine the intersection of critical minerals with just transition governance and explore possibilities for more plural, holistic and integrated just energy transition pathways. In this introduction article, we detail the ways in which the production of low-carbon technologies is bound up with global inequalities and ongoing coloniality. We then demonstrate the importance of adopting a global, inclusive outlook on just energy transitions. Drawing from the concept of planetary just transition, we provide an overview of the key debates around the role of critical minerals in a just energy transition.

Maximized Lanthanide Extraction Using Supercritical CO2 and Fluorinated Organophosphate Extractants

Maximized Lanthanide Extraction Using Supercritical CO₂ and Fluorinated Organophosphate Extractants

Intra-lanthanide separation performance of DOTP: Solid-phase extraction and selective precipitation studies

The applicability of 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetra(methylene phosphonic acid) (DOTP) for intra-lanthanide (Ln) separation was investigated through two approaches: the synthesis of inorganic–organic hybrid sorbents and selective precipitation in an aqueous solution. Hybrid sorbents combining zirconium oxide and DOTP were fabricated through post-synthetic grafting and hydrothermal synthesis. The successful syntheses were verified by FTIR and 31P magic-angle spinning (MAS) NMR spectroscopies. All the hybrid sorbents showed a lanthanide uptake of approximately 10–20 μmol/g at pH 3 and displayed only moderate selectivity, with the highest separation factor (SF) of about 10 for Lu3+ over La3+. In contrast, the selective precipitation of lanthanides by DOTP in an aqueous solution was successful in the presence of Cu2+. When a Cu-DOTP complex was introduced into a La/Lu equimolar solution, lanthanide ions were selectively precipitated with an SF of approximately 30–190. When the initial stoichiometry was set to Ln:Cu-DOTP = 8:1, roughly 95 % of the lanthanides in the precipitate were Lu3+, regardless of the pH ranging from 3 to 5. This precipitation process demonstrated selectivity even for adjacent lanthanide pairs. The selectivity is assumed to be a result of structural variations in the precipitates of Ln-Cu-DOTP, which is supported by the characterization results obtained from X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and UV–Vis spectroscopy. The findings presented in this study indicate that DOTP has the potential for use in the selective extraction of lanthanides, which may offer promising advancements in intra-lanthanide separation.

Selective extraction and recovery of rare earth elements from coal fly ash by carboxylated mesoporous carbon

The separation of Rare Earth Elements (REEs) from non-conventional sources is very critical to maintain the supply-chain balance of REEs in the Western world. Despite Coal Fly Ash (CFA) being designated as a prominent non-conventional source of REEs and several studies have reported on the extraction of REEs from CFA, the selectivity of REEs with respect to non-REEs in the CFA has never been reported. In this work, for the time, we have reported the selectivity of REEs over non-REEs using carboxylated mesoporous carbon (CMC) as the sorbent. The CMC was produced by carboxylating the soft-templated mesoporous carbon and then it was characterized successfully for porosity, FTIR, and SEM-EDX. The leachate produced from REEs contains 16 REEs and 20 non-REEs from groups 1 through 3 and 6 through 15 of the modern periodic table. The REEs were extracted within 80–90% in the 3 cycles along with the elements from groups of 1,3, 5, 8, and 11. Although a few other elements were also extracted, the values of the distribution coefficient confirmed that the CMC has a much higher affinity towards REEs except the non-REEs from groups 1 and 3. In the recovery mode, the REEs were recovered in the range of 20–100%, and heavier REEs demonstrated a better recovery. The recovery percent of non-REEs was also much lower compared to that of REEs, except for the elements from groups 3, 8, and 11. The non-REEs from group 3 demonstrated the highest competition, which can be attributed to the fact the REEs also belong to the same group of the periodic table. The ratio of extracted and recovered REEs over non-REEs was always greater than unity, suggesting that the CMC was selective towards REEs over non-REEs in extraction and recovery. The overall results suggest that CMC can potentially be used for selective extraction and recovery of REEs from coal fly ash.

Effect of Ionic Liquid on the Extraction of Lanthanides(III) from Nitric Acid Solutions with Phosphoryl-Containing Podands

Effect of Ionic Liquid on the Extraction of Lanthanides(III) from Nitric Acid Solutions with Phosphoryl-Containing Podands

Rare Earth Element Speciation in Coal and Coal Combustion Byproducts: A XANES and EXAFS Study.

Transitioning to a low-carbon economy, necessary to mitigate the impacts of anthropogenic climate change, will lead to a significant increase in demand for critical minerals such as rare earth elements (REE). Meeting these raw materials requirements will be challenging, so there is increasing interest in new sources of REE including coal combustion byproducts (CCBs). Extraction of REE from CCBs can be advantageous as it involves reusing a waste product, thereby contributing to the circular economy. While a growing body of literature reports on the abundance of REE in CCBs globally, studies examining the key factors which control their recovery, including speciation and mode of occurrence, are lacking. This study employed synchrotron-based X-ray absorption spectroscopy to probe the speciation and local bonding environment of yttrium in coals and their associated CCBs. Linear Combination Fitting identified silicate and phosphate minerals as the dominant REE-bearing phases. Taken together with the results of extended X-ray absorption fine structure (EXAFS) curve fitting, we find there is minimal transformation in the REE host phase during combustion, indicating it is transferred in bulk from the coals to the CCBs. Accordingly, these findings can be incorporated into the development of an efficient, environmentally conscious recovery process.

Extractability and mineralogical evaluation of rare earth elements from Waterberg Coalfield run-of-mine and discard coal

This study explores the extraction of rare earth elements (REEs) from high-ash run-of-mine and discard coal sourced from the Waterberg Coalfield. Three distinct methods were employed: (1) ultrasonic-assisted caustic digestion; (2) direct acid leaching; and (3) ultrasonic-assisted caustic-acid leaching. Inductively coupled plasma mass spectrometry was utilized to quantify REEs in both the coals and resultant leachates. Leaching the coals with 40% NaOH at 80 °C, along with 40 kHz sonication, yielded a total rare earth element (TREE) recovery of less than 2%. Notable enrichment of REEs was observed in the run-of-mine and discard coal by 17% and 19%, respectively. Upon employing 7.5% HCl, a recovery of less than 11.0% for TREE was achieved in both coal samples. However, leaching the caustic digested coal samples with 7.5% HCl significantly enhanced the TREE recovery to 88.8% and 80.0% for run-of-mine and discard coal, respectively. X-ray diffraction analysis identified kaolinite and quartz as the predominant minerals. Scanning electron microscopy-energy dispersive microanalysis revealed monazite and xenotime as the REE-bearing minerals within the coal samples. These minerals were found either liberated, attached to, or encapsulated by the clay-quartz matrices. Further mineralogical assessments highlighted the increased REE concentrations in coals post-caustic digestion and subsequent recovery during acid leaching. This increase was attributed to the partial dissolution of kaolinite encapsulating the RE-phosphates and the digestion of REE-bearing minerals. Notably, undissolved REE-bearing elements in the caustic-acid-leached coal indicated the necessity of harsh leaching conditions to augment REE recovery from these coal samples.

Microbial consortia-driven bioweathering provides new potential for sustainable recovery of rare earth elements (REE) in fly ash: From metagenome exploration to performance verification

This study presents a novel approach to extracting rare earth elements (REE) from fly ash (FA) using environmentally adapted microbial consortia, highlighting a sustainable alternative to traditional extraction methods. Through comprehensive geochemical characterization of FA obtained from a power plant in China, a complex matrix rich in REE was identified. Microbial consortia isolated from both sludge and FA demonstrated distinct and interactive communities with specialized adaptations for REE bioweathering, as revealed by metagenomic analysis and molecular ecological network assessments. These communities exhibited diverse metabolic profiles, emphasizing ion transport, energy production, and carbohydrate and lipid metabolism tailored to their specific environmental contexts. Enzymatic profiling further elucidated the critical roles of siderophore production and redox reactions in the bioweathering process. Ex-situ bioweathering experiments showcased the consortia's capability to efficiently mobilize specific REE. Notably, under optimized conditions (10 % inoculum of Sludge_LB at 30 °C), significant extraction efficiencies were observed, such as 0.119 mg/g for Sc and 0.068 mg/g for Y; similarly, 10 % inoculum of FA_M9 at 30 °C showed an extraction efficiency of 0.036 mg/g for La. Recovery rates for various REE ranged from 29 % to 83 %, were obtained in a short time (48 hours) demonstrates the effectiveness of this method. These results demonstrate the sustainability of microbial consortia for REE extraction, offering reduced environmental impact compared to conventional methods. This research not only provides a viable method for REE recovery from industrial waste but also contributes to broader goals of sustainable resource utilization and environmental protection.

Interface Modulation of 2D Superlattice Heterostructures with Oxygen-enriched Sites and Dissolution Restraint for Effective Rare-earth Elements Extraction

Effective recovery of rare earth elements from wastewater is crucial for the modern industry, as well as for protecting the human health and ecosystem. Nevertheless, it is still challenging to realize efficient and selective low-concentration rare earth extraction in systems containing high levels competing metal ions. Here, we report on the fabrication of two-dimensional superlattice heterostructures (VOGO-x) through the alternating restacking of VOPO4 nanosheets and GO-PDDA nanosheets via electrostatic self-assembly. The meticulously organized molecular scale of superlattice heterostructures enable the full exposure of accessible adsorption sites and facilitate the transport of rare earth ions, meanwhile the abundant oxygen-containing phosphate groups within the interlayer can realize selective rare earth ions extraction. Furthermore, the tunable interlayer interaction can promote structure stability to prevent dissolution. Consequently, VOGO-11 possesses excellent rare earth adsorption performance, with a saturated adsorption capacity (Nd(III) 631.52 mg/g, Dy(III) 689.48 mg/g, Lu(III) 716.06 mg/g), high utilization rate of adsorption sites and short adsorption equilibrium time of simply 10 min in the REE aqueous solution. Furthermore, VOGO-11 exhibits outstanding selective rare earth adsorption ability over a wide range of metal ions in the low-concentration simulated wastewater and actual leaching tailings. These results demonstrate the material’s promising potential in capturing rare earth ions and pave the way to the development of two-dimensional superlattice heterostructures through interface modulation for effective rare earth extraction.

Extraction of Rare Earth Elements from Water by Trioctylphosphine Oxide-Based Hydrophobic Deep Eutectic Solvents

Extraction of Rare Earth Elements from Water by Trioctylphosphine Oxide-Based Hydrophobic Deep Eutectic Solvents

Biomining using microalgae to recover rare earth elements (REEs) from bauxite

Biomining using microalgae has emerged as a sustainable option to extract rare earth elements (REEs). This study aims to (i) explore the capability of REEs recovery from bauxite by microalgae, (ii) assess the change of biochemical function affected by bauxite, and (iii) investigate the effects of operating conditions (i.e., aeration rate, pH, hydraulic retention time) to REEs recovery. The results showed that increasing bauxite in microalgae culture increases REEs recovery in biomass and production of biochemical compounds (e.g., pigments and Ca-Mg ATPase enzyme) up to 10 %. The optimum pulp ratio of bauxite in the microalgae culture ranges from 0.2 % to 0.6 %. Chlorella vulgaris was the most promising, with two times higher in REEs recovery in biomass than the other species. REEs accumulated in microalgae biomass decreased with increasing pH in the culture. This study establishes a platform to make the scaling up of REEs biomining by microalgae plausible.

Extraction of Actinides and Lanthanides from Nitric Acid Solutions with Mixtures of 1,5-N,N'-Bis[(Diphenylphosphoryl)Acetyl(Hexyl)Amino]pentane and New Asymmetrical Phosphonium- and Imidazolium-Based Ionic Liquid

Extraction of Actinides and Lanthanides from Nitric Acid Solutions with Mixtures of 1,5-N,N'-Bis[(Diphenylphosphoryl)Acetyl(Hexyl)Amino]pentane and New Asymmetrical Phosphonium- and Imidazolium-Based Ionic Liquid

Optimization of rare earth magnet recovery processes using oxalic acid in precipitation stripping: Insights from experimental investigation and statistical analysis

Recycling the valuable metals found in spent permanent magnets (REPMs) poses a significant global challenge for the future. This study examines the efficiency of back extraction of rare earth elements (REEs) by oxalic acid solution from di-(2-ethylhexyl) phosphoric acid (D2EHPA) in recycling REPMs. To evaluate the efficiency of this process, several experiments were carried out using designed BOX-Behnken methodology to investigate the effects of various operational and chemical parameters, including stripping solution to loaded organic phase volume ratio (in the range of 1.0–2.0), oxalic acid concentration (ranging from 0.25 to 0.75 M), the stirring rate (ranged between 150 and 350 rpm), and stripping time (ranging from 15 to 45 min) on the REEs recovery and the purity of final production. Analysis of variance was applied to rigorously examine the results statistically. The results showed that more than 85 % of light and 80 % of heavy REEs can be recovered under optimal conditions. Moreover, the final product contained 43.5 % REEs and approximately 0.1 % iron. The stripping experiment using phosphoric acid as the reagent demonstrated ∼57 % light and ∼4 % heavy REEs recovery. Additionally, the recyclability of the organic phase showed its effective reuse for up to four cycles. This study underscores significant progress in the selective recovery of rare earth elements through a relatively straightforward process consuming mild reagents.