Eu Gd Research Articles

Optimization of ion-pairing HPLC method for mutual separation of rare earth elements: unveiling the “diad-effect” appraisal utilizing periodic variations in their properties

A new ion-pairing HPLC method has been developed for the analytical separation of rare earth elements (REEs), utilizing the unique “diad-effect” of the lanthanides. A chemometric approach was used to optimize the separation process, examining the impact of mobile phase pH and ion-pairing reagent concentration on resolution and elution time. A triple gradient elution program was proposed, involving changes in the pH of the mobile phase from 3.5 to 4.5, the ion-pairing reagent concentration from 25 mM to 0.05 M, and the mobile phase complexing additive (hydroxyisobutyric acid) concentration from 0.05 M to 0.5 M. With the proposed method, all REEs, including pairs that are typically difficult to separate (Pr–Nd, Eu–Gd, and Dy–Y), were effectively separated in less than eight minutes. The method validation conducted following ICH guidelines showed accurate results, with an accuracy of 99–108% across a concentration range of 50–150% of the target concentration for REEs. It also exhibited good linearity (0.9998–0.9992) across a concentration range of 5–15 µg/mL for REEs and a detection limit of 0.27–0.98 µg/mL for the various species. The proposed HPLC method proved reliable and successfully separated a commercial sample of yttrium-group oxides.

Heterobimetallic lanthanide tetrahedral cages: Synthesis, design and application for potential multimodal imaging contrast agent

The construction and functionalization of lanthanide-organic cages have been a research hotspot in coordination chemistry. Benefiting from the unique luminescent and magnetic properties of lanthanide ions, the potential applications of lanthanide-organic cages in biological imaging applications are promising, but only a few corresponding explorations have been reported. Herein, we introduced a series of lanthanide tetrahedral cages, (EunGd4–nL4) (sol)8 (n = 0, 1, 2, 3 and 4, where L = (4,4′,4″-tris(4,4,4-trifluoro-1,3-dioxobutyl)-triphenylamine, and sol = dimethyl sulfoxide and methanol), with potential applications in biological imaging. Given the good luminescent and magnetic properties of Eu3+ and Gd3+ ions, Eu4L4 and Gd4L4 complexes show a high luminescence quantum yield of 29% in DMSO and large longitudinal relaxivity (r1) of 11.4 (mmol/L)−1/s at 0.5 T in water containing 1 vol% DMSO, respectively. The heterobimetallic Eu–Gd complexes achieve a dual imaging mode by combining luminescent and magnetic centers in one cage. When the Gd:Eu ratio increases from 1:3 to 3:1, the r1 values increases from 5.33 to 8.64 (mmol/L)−1/s, higher than that of commercial contrast agent Gd-DOTA (3.23 (mmol/L)−1/s). Owing to their low toxicity and good cell imaging ability toward ECA 109 cells, the self-assembled Eu–Gd heterobimetallic tetrahedral cages could be potential candidates for the multimodal imaging contrast agent.

2.E. Workshop: Health in Green Deal and Climate Pact

Abstract Health does not only imply the absence of disease but complete physical, mental and social well-being as well. Nowadays, it seems, more than ever, that we are aware of how solemn these words are and how unreachable health is. Public health can be regarded as the science and art of achieving health in the community and implementing preventive measures and all activities contributing to public health. However, this cannot be achieved without proper environmental conditions. The EU Green Deal (EU GD) and the Climate Pact (CP) initiative, provide a clear trajectory and highlights priorities for improving the environment. Since the pollution emitted in one country affects other countries, the scope of the EU GD encompasses the whole continent, including the Western Balkans. South east Europe will be used as a case study in this workshop. The workshop is dedicated to the topic of the EU GD and the CP and connecting research, project activities and the activities of citizens and civil society in achieving the set goals of the EU Green Deal. Health impact assessment (HIA) combined with scenario analysis provides useful quantitative estimations about the implications of air quality policies that should be used for air quality management design. The impact of these international initiatives and its instruments will be analysed. Will this improve the health situation enough? Priority task of EU GD is certainly to improve of air quality throughout Europe, which requires research into the best ways for HIA of air pollution. The activities in engaging with key decision makers involved in climate change and health adaptation across Europe, providing knowledge, understanding interlinkages and identifying areas for action to promote climate policies that enhance health benefits will be presented by ENBEL project. Public health professionals should insist on health in these priorities, use them to reduce externalities, activate citizens to contribute through certain individual and non-health-related decisions and invest in the health of future generations. The GD and the CP are therefore essential processes for improving both individual and public health. An example, by delivering on the Green Deal's zero pollution ambition for health, which will be presented by HEAL. Furthermore, the role of Climate Pact Ambassadors (CPA) could be used as opportunity for dissemination aims and mission of EU GD, Western Balkan Green Agenda, as well as to provide better communication, collaboration and actions among researchers, citizens and decision makers. CPA could help in advocacy and actions to achieve better health through EU GD and CP.

Ferromagnetic alloy for high-efficiency photovoltaic conversion in solar cells: first-principles insights when doping SnO2 rutile with coupled Eu-Gd.

From results of first-principles all-electron full-potential augmented spherical-wave calculations within a generalized gradient approximation, a materials design for half-metallic ferromagnetic semiconductors based on (Eu,Gd)-doped SnO2 rutile is proposed. Moreover, their half-metallic ferromagnetic properties are homogenous and energetically stable for different crystallographic directions. Therefore, the interatomic exchange interaction between the spins of double impurity ions is a long-range ferromagnetic interaction that is sharply weakened when the distance between Eu–Gd increases. The double impurities most likely substitute adjacent Sn sites and result in strong ferromagnetic interactions by p–f hybridization between rare earth 4f and Op states. There is great interest in the configuration that has the lowest energy difference, where the double impurity substitutes the nearest neighbor Sn sites along the z-axis of SnO2 rutile. Generalized gradient approximation GGA and GGA+U calculations were performed. According to our revPBE-GGA calculations, the ferromagnetic compound is capable of absorbing 96% from the visible light. Furthermore, the transport properties at room temperature ensure excellent electrical conductivity, low thermal conductivity, and the most optimal figure of merit (ZT), which leads to high thermoelectric performance. As the latter are closely related to free flow charge carriers, we can subsequently predict that the ferromagnetic alloy will be able to be a great power source for highly effective photovoltaic conversion in solar cells. Further experimentation will be necessary to obtain confirmation of our ab initio predictions.

Ultrasmall Mixed Eu-Gd Oxide Nanoparticles for Multimodal Fluorescence and Magnetic Resonance Imaging of Passive Accumulation and Retention in TBI.

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide. TBI can have a long-term impact on the quality of life for survivors of all ages. However, there remains no approved treatment that improves outcomes following TBI, which is partially due to poor delivery of therapies into the brain. Therefore, there is a significant unmet need to develop more effective delivery strategies that increase the accumulation and retention of potentially efficacious treatments in the injured brain. Recent work has revealed that nanoparticles (NPs) may offer a promising approach for site-specific delivery; however, a detailed understanding of the specific NP properties that promote brain accumulation and retention are still being developed. Multimodal imaging plays a vital role in the understanding of physicochemical properties that initiate the uptake and accumulation of NPs in the brain at both high spatial (e.g., fluorescence imaging) and temporal (e.g., magnetic resonance imaging, MRI) frequency. However, many NP systems that are currently used in TBI only provide contrast in a single imaging modality limiting the imaging data that can be obtained, and those that offer multimodal imaging capabilities have complicated multistep synthesis methods. Therefore, the goal of this work was to develop an ultrasmall NP with simple fabrication capable of multimodal imaging. Here, we describe the development, characterization, accumulation, and retention of poly(ethylene glycol) (PEG)-coated europium–gadolinium (Eu–Gd) mixed magnetic NPs (MNPs) in a controlled cortical impact mouse model of TBI. We find that these NPs having an ultrasmall core size of 2 nm and a small hydrodynamic size of 13.5 nm can be detected in both fluorescence and MR imaging modalities and rapidly accumulate and are retained in injured brain parenchyma. These NPs should allow for further testing of NP physicochemical properties that promote accumulation and retention in TBI and other disease models.

Extraction Separation of Rare Earth Elements of the Medium Group with Isomolar Mixtures of Aliquat®336–TBP and Cyanex®572–TBP from Nitric Solutions

The results of extraction separation of the medium group of rare earth elements in the composition of the concentrate of JSC SMF with isomolar mixtures of Aliquat®336–TBP and Cyanex®572–TBP from nitric solutions are discussed. The influence of acidity of an aqueous solution on separation factors of representative pairs of REE and on the value of the capacity of mixtures of extractants is studied. The possibility of extraction separation on the lines of Sm–Gd and Eu–Gd (Aliquat®336–TBP) and on the line of Eu–Sm (Cyanex®572–TBP) is shown.

Geology and geochemistry of the Xiaoshanba bauxite deposit, Central Guizhou Province, SW China: Implications for the behavior of trace and rare earth elements

In China, bauxite is mainly of the karst type. Karst bauxite deposits in Central Guizhou are widely distributed in the Qingzhen, Xiuwen, and Zunyi districts. The Xiaoshanba deposit is located in the Xiuwen district and is hosted in the Lower Carboniferous Jiujialu Formation. It shows parallel unconformity with the overlying and underlying strata. The main chemical contents of the bauxite ore in the Xiuwen district is Al2O3 (55.7 to 73.5 wt%), followed by SiO2, Fe2O3, TiO2, CaO, MgO, S, P, etc. There are obvious enrichments in rare earth elements (REEs) and immobile trace elements (such as Ti, Nb, Zr, Hf, Ta, and Th) in the Al-bearing rocks.The mass change calculation (MC) is an effective means of investigating the relative mobility of elements. Here we present the multiples of mass change calculation (MMC), which represents an improvement over the MC, and is effective for element mobile investigations. The MMC results for REEs of the Xiaohsanba Al-bearing rocks showed grouping phenomenon, in which REEs were divided into four groups (Group A: La–Ce–Pr–Nd; Group B: Pm–Sm–Eu–Gd; Group C: Gd–Tb–Dy–Ho, and Group D: Er–Tm–Yb–Lu) and showed different fractionation trends in the MMC curves. The tetrad characteristic of the REEs (tetrad effects) most likely induced the special grouping phenomenon. During bauxite mineralization, REE fractionations caused by mineral control, especially the widespread distribution of accessory minerals that are rich in REEs such as Ti-dioxide minerals (i.e., TiO2 such as rutile and anatase) and zircon, and water–rock interactions resulted in the REE grouping phenomenon in the Xiaoshanba profile.The majority of these immobile elements tend to concentrate in the accessory minerals of bauxite, and barely any elements (except Li and Ga) seem associated with the ore-forming minerals. For instance, Ti-dioxide minerals played an important role in the accumulation of some elements, such as Ti, V, Nb, and Ta. Another important mineral was zircon, which is rich in Zr, Hf, and Th, etc. In general, there were two main factors that influence the content of immobile elements in the karst bauxite profile: (a) the chemical composition of the precursor rock (the higher the content of immobile elements in the parent rock, the higher the content of accessory minerals and immobile elements in bauxite), and (b) the weathering degree of the precursor rock (the stronger the degree of weathering, the higher the content of accessory minerals and immobile elements in bauxite).

RGD/CTX-conjugated multifunctional Eu-Gd2O3 NRs for targeting detection and inhibition of early tumor.

Glioblastoma is currently the most common and lethal brain tumor, so accurate detection and effective therapy at the early glioblastoma stage is crucial. Herein, multifunctional Eu-Gd2O3 nanorods (NRs) with good paramagnetic and luminescence properties were fabricated through a hydrothermal method and a subsequent calcination technique, and exhibited good T1-weighted magnetic resonance (MR) imaging (r1 = 5.13 Gd mM-1 s-1) and cell-luminescence imaging properties. Then, Eu-Gd2O3 NRs were coated with difunctionalized polyethylene glycol (Mal-PEG-NHS), and subsequently conjugated through thiolation with arginine-glycine-aspartic (RGD) and chlorotoxin (CTX), respectively. The results of the cell test indicated that RGD/CTX-conjugated Eu-Gd2O3 NRs (RGD-NRs-CTX) could specifically target and adhere on U251 cells, leading to cellular apoptosis. The in vivo investigation revealed that RGD-NRs-CTX possessed no tissue/organ toxicity and a long blood circulation time. The results of in vivo MR imaging showed a significant preferential targeting and accumulation of RGD-NRs-CTX onto the early tumor, and in vivo luminescence imaging displayed a good infiltration capacity in tumor regions. Based on a superimposed targeting property of CTX and RGD, the results of everyday tail-vein injection suggested that RGD-NRs-CTX could effectively inhibit early tumor growth, without any damage to normal tissues/organs. Therefore, these results demonstrate that RGD-NRs-CTX are promising candidates for simultaneous targeting detection and therapy for early tumor.

Europium and strontium anomalies in the MORB source mantle

Lower crustal recycling depletes the continental crust of Eu and Sr and returns Eu and Sr enriched materials into the mantle (e.g., Tang et al., 2015, Geology). To test the hypothesis that the MORB source mantle balances the Eu and Sr deficits in the continental crust, we carried out high precision Eu/Eu∗ and Sr/Sr∗ measurement for 72 MORB glasses with MgO >8.5% from the Pacific, Indian, and Atlantic mid-ocean ridges. MORB glasses with MgO⩾9wt.% have a mean Eu/Eu∗ of 1.025±0.025 (2 σm, n=46) and Sr/Sr∗ of 1.242±0.093 (2 σm, n=41) and these ratios are positively correlated. These samples show both positive and negative Eu and Sr anomalies, with no correlations between Eu/Eu∗ vs. MgO or Sr/Sr∗ vs. MgO, suggesting that the anomalies are not produced by plagioclase fractionation at MgO >9wt.% and, thus, other processes must be responsible for generating the anomalies. We term these MORB samples primitive MORBs, as they record the melt Eu/Eu∗ and Sr/Sr∗ before plagioclase fractionation. Consequently, the mean oceanic crust, including cumulates, has a bulk Eu/Eu∗ of ∼1 and 20% Sr excess.Considering that divalent Sr and Eu(II) diffuse faster than trivalent Pr, Nd, Sm, and Gd, we evaluated this kinetic effect on Sm–Eu–Gd and Pr–Sr–Nd fractionations during spinel peridotite partial melting in the MORB source mantle. Our modeling shows that the correlated Eu and Sr anomalies seen in primitive MORBs may result from disequilibrium mantle melting. Melt fractions produced during early- and late-stage melting may carry positive and negative Eu and Sr anomalies, respectively, that overlap with the ranges documented in primitive MORBs. Because the net effect of disequilibrium melting is to produce partial melts with bulk positive Eu and Sr anomalies, the MORB source mantle must have Eu/Eu∗<1.025±0.025 (2 σm) and Sr/Sr∗<1.242±0.093 (2 σm). Although we cannot rule out the possibility that recycled lower continental crustal materials, which have positive Eu and Sr anomalies, are partially mixed into the upper mantle (i.e., MORB source region), a significant amount of this crustal component must have been sequestered into the deep mantle, as supported by the negative 206Pb/204Pb–Eu/Eu∗ and 206Pb/204Pb–Sr/Sr∗ correlations in ocean island basalts.

Tuning of exchange by band filling in low-carrier-density magnet Eu(Gd)B6

Tuning of exchange by band filling in low-carrier-density magnet Eu(Gd)B₆

Ultrafast optical tuning of ferromagnetism via the carrier density.

Interest in manipulating the magnetic order by ultrashort laser pulses has thrived since it was observed that such pulses can be used to alter the magnetization on a sub-picosecond timescale. Usually this involves demagnetization by laser heating or, in rare cases, a transient increase of magnetization. Here we demonstrate a mechanism that allows the magnetic order of a material to be enhanced or attenuated at will. This is possible in systems simultaneously possessing a low, tunable density of conduction band carriers and a high density of magnetic moments. In such systems, the thermalization time can be set such that adiabatic processes dominate the photoinduced change of the magnetic order--the three-temperature model for interacting thermalized electron, spin and lattice reservoirs is bypassed. In ferromagnetic Eu(1-x)Gd(x)O, we thereby demonstrate the strengthening as well as the weakening of the magnetic order by ~10% and within ≤3 ps by optically controlling the magnetic exchange interaction.

Temperature Dependence of the Electronic Structure and Fermi-Surface Reconstruction ofEu1−xGdxOthrough the Ferromagnetic Metal-Insulator Transition

We present angle-resolved photoemission spectroscopy of Eu(1-x)Gd(x)O through the ferromagnetic metal-insulator transition. In the ferromagnetic phase, we observe Fermi surface pockets at the Brillouin zone boundary, consistent with density functional theory, which predicts a half-metal. Upon warming into the paramagnetic state, our results reveal a strong momentum-dependent evolution of the electronic structure, where the metallic states at the zone boundary are replaced by pseudogapped states at the Brillouin zone center due to the absence of magnetic long-range order of the Eu 4f moments.

Electron-Deficient Eu6.5Gd0.5Ge6 Intermetallic: A Layered Intergrowth Phase of the Gd5Si4- and FeB-Type Structures

A novel electron-poor Eu(6.5)Gd(0.5)Ge₆ compound adopts the Ca₇Sn₆-type structure (space group Pnma, Z = 4, a = 7.5943(5) Å, b = 22.905(1) Å, c = 8.3610(4) Å, and V = 1454.4(1) ų). The compound can be seen as an intergrowth of the Gd₅Si₄-type (Pnma) R₅Ge₄ (R = rare earth) and FeB-type (Pnma) RGe compounds. The phase analysis suggests that the Eu(7-x)Gd(x)Ge₆ series displays a narrow homogneity range of stabilizing the Ca₇Sn₆ structure at x ≈ 0.5. The structural results illustrate the structural rigidity of the ²(∝)[R₅X₄] slabs (X = p-element) and a possibility for discovering new intermetallics by combining the ²(∝)[R₅X₄] slabs with other symmetry-approximate building blocks. Electronic structure analysis suggests that the stability and composition of Eu(6.5)Gd(0.5)Ge₆ represents a compromise between the valence electron concentration, bonding, and existence of the neighboring EuGe and (Eu,Gd)₅Ge₄ phases.

Synthesis and magnetic properties of Gd doped EuS nanocrystals with enhanced Curie temperatures.

EuS nanocrystals (NCs) were doped with Gd resulting in an enhancement of their magnetic properties. New EuS and GdS single source precursors (SSPs) were synthesized, characterized, and employed to synthesize Eu(1-x)Gd(x)S NCs by decomposition in oleylamine and trioctylphosphine at 290 °C. The doped NCs were characterized using X-ray diffraction, transmission electron microscopy, and scanning transmission electron microscopy, which support the uniform distribution of Gd dopants through electron energy loss spectroscopy (EELS) mapping. X-ray absorption spectroscopy (XAS) revealed the dopant ions in Eu(1-x)Gd(x)S NCs to be predominantly Gd(3+). NCs with a variety of doping ratios of Gd (0 ≤ x < 1) were systematically studied using vibrating sample magnetometry and the observed magnetic properties were correlated with the Gd doping levels (x) as quantified with ICP-AES. Enhancement of the Curie temperature (T(C)) was observed for samples with low Gd concentrations (x ≤ 10%) with a maximum T(C) of 29.4 K observed for NCs containing 5.3% Gd. Overall, the observed T(C), Weiss temperature (θ), and hysteretic behavior correspond directly to the doping level in Eu(1-x)Gd(x)S NCs and the trends qualitatively follow those previously reported for bulk and thin film samples.

Rare earth element signatures in the Messinian pre-evaporitic Calcare di Base formation (Northern Calabria, Italy): evidence of normal seawater deposition

The Calcare di Base (CdB), a carbonate unit deposited at the base of the evaporitic succession, is a key to understanding the paleoenvironmental conditions before the Messinian Salinity Crisis. The concentration of rare earth elements and yttrium (REE + Y) in the CdB, cropping out in the Rossano Basin, were measured with inductively coupled mass spectrometry (ICP-MS). The CdB shows coherent and reliable REE + Y patterns with typical characteristics of microbial carbonates: (1) enrichment in heavy REE (NdSN/YbSN = 0.52, SD = 0.09), (2) negative Ce and positive La anomalies, (3) marine Y/Ho ratios (57.08, SD = 3.07), (4) slightly positive Gd anomalies, and (5) tetrad effect especially in the La–Ce–Pr–Nd, and [Pm]–Sm–Eu–Gd tetrads. These features suggest that the CdB incorporated REEs in equilibrium with oxygenated seawater. They also corroborate the depositional model of Guido et al. in Palaeogeogr Palaeoclimatol Palaeoecol 255:265–283, (2007) that maintains carbonatogenesis occurred via heterotrophic microbial activity. The REE + Y signatures of the CdB support the interpretation that these sediments were deposited in normal marine condition and cannot belong to the evaporite succession.

Geochemical distinctions between “crustal” and mantle-derived peridotites/pyroxenites in high/ultrahigh pressure metamorphic complexes

Basic and ultrabasic rocks in high- and ultrahigh-pressure collision belts can provide important petrological information. Mantle-derived and “crustal” peridotites and pyroxenites are recognized among these rocks in Phanerozoic orogenic zones. The former were emplaced as mantle magma intrusions or tectonically transferred solid fragments of mantle material in the deeply subsided lithosphere, while the latter are shallow complexes of dikes and sills, which were altered and metamorphosed during subduction process. Both rock types were later exhumed at the Earth's surface. For geochemical comparison of these types, four groups of rocks were chosen: two sample sets of mantle-derived rocks and two sets of crustal rocks. The mantle-derived rocks include a set of spinel and garnet peridotites of alpine-type bodies from the Eastern and Western Alps and the Ronda massif in Spain as well as a set of pyroxenites from the Eastern Alps. The “crustal” rocks include a set of garnet and spinel peridotites from the Kokchetav massif, northern Kazakhstan, and garnet peridotites from the Western Gneiss Region, western Norway, together with a set of pyroxenites from the Kokchetav massif. Geochemical investigation has revealed that mantle-derived peridotites are characterized, as a rule, by high contents of MgO (35–46 wt.%), Cr (1750–12,770 ppm), and Ni (900–2500 ppm), low contents of FeO (5–10 wt.%), TiO 2 (0.01–0.3 wt.%), Zr (0.002–1.2 ppm), Nb (0.001–0.3 ppm), Sm (0.003–0.5 ppm), La (0.005–1 ppm), and Yb (0.006–0.54 ppm), and the total content of REE equal to 0.06–5.2 ppm. Mantle-derived pyroxenites contain 27–35 wt.% MgO, 2300–3300 ppm Cr, 5.5–9 wt.% FeO, 0.02–0.08 wt.% TiO 2, 0.2–1.4 ppm Zr, 0.007–0.06 ppm Nb, 0–0.13 ppm Sm, 0.007–0.23 ppm La, 0.02–0.2 ppm Yb, and 0.05–1.6 ppm total REE. “Crustal” peridotites are characterized by high contents of FeO (12–25 wt.%), TiO 2 (0.64–2.6 wt.%), Zr (33–179 ppm), Nb (3.4–13.8 ppm), Sm (0.7–4 ppm), La (1–8 ppm), Yb (0.8–3.3 ppm), and total REE (11.5–48 ppm) as well as by comparatively low contents of MgO (15–26 wt.%), Cr (79–244 ppm), and Ni (450–730 ppm). “Crustal” pyroxenites contain 6–21.5 wt.% MgO, 90–230 ppm Cr, 11–21 wt.% FeO, 0.7–1.3 wt.% TiO 2, 45–493 ppm Zr, 1–8 Nb, 1.6–4.3 ppm Sm, 4.7–14 ppm La, 1.3–7.4 ppm Yb, and 27–80 ppm total REE. These data permit us to develop D. Carswell's idea of distinctions between the mantle-derived and “crustal” peridotites and suggest some promising geochemical criteria. The criteria are based on distinctions between the contents of MgO, FeO, TiO 2, Cr, Ni, Zr, Nb, REE, etc. in peridotites and pyroxenites. Binary MgO–Cr, FeO–TiO 2, La–Yb, Lu–Nd, Eu–Gd, and Sm–ΣREE diagrams give an opportunity to discriminate the compositions in detail and are the most appropriate for practical use. The obtained information may be helpful in understanding the nature of protoliths when studying mafic/ultramafic granulites in high-grade metamorphic rocks.

Hydrothermal Synthesis, Structural Investigation, Photoluminescence Features, and Emission Quantum Yield of Eu and Eu—Gd Silicates with Apatite‐Type Structure.

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The Co-luminescence Effect of Eu–Gd–Ofloxacin–SDBS System and its Analytical Application

A fluorescence enhancement phenomenon in the europium (Eu)-Ofloxacin (OF)-Sodium Dodecyl Benzene Sulfonate (SDBS) fluorescence system was observed when Gd(3+) was added. The fluorescence intensity of the systems was measured (lambda (ex)/lambda (em) = 280/612 nm) at pH 7.8. Under optimum conditions, a linear relationship between the enhanced fluorescence intensity and the Eu(3+) concentration in the range of 5.0 x 10(-10) approximately 2.0 x 10(-7) mol x L(-1) was observed. The detection limit of Eu(3+) was 1.46 x 10(-10) mol x L(-1) (S/N = 3). This method was used for the determination of trace amounts of europium in synthetic rare earth samples with satisfactory results. In addition, the interaction mechanism is also studied.

Trinuclear lanthanide complexes of a compartmental ligand N,N′-bis(2-pyridinyl)-2,6-pyridinedicarboxamide: A spectroscopic investigation

Trinuclear lanthanide complexes of the formula [Ln3(PPDA)(NO3)6(H2O)2]·NO3·2H2O where Ln=La(III), Pr(III), Sm(III), Nd(III), Eu(III) Gd(III) Tb(III), Dy(III) and Y(III); H2PPDA=N,N′-bis(2-pyridinyl)-2,6-pyridinedicarboxamide, have been isolated. The complexes were characterized by elemental analyses, conductivity measurements, magnetic susceptibility measurements and spectral (IR, NMR, UV–vis, fluorescence, FAB and EPR) and thermal studies.

Separation and Recovery of Rare Earths in Reciprocating Extraction Columns

Multi‐component rare earth (RE) separation (Nd group/Sm group) and recovery (Nd group) in sulfuric acid solution by di(2‐ethyl‐hexyl) phosphoric acid (D2EHPA) dissolved in kerosene were investigated using two 3.7 cm inner diameter reciprocating extraction columns (RPCs) (height: 5.0–5.6 m) connected in sequence. The height equivalent to a theoretical stage (HETS) for Nd group/Sm group separation was in the range of 0.80–0.90 m and 0.66 m for extraction and scrubbing process, respectively. Under testing conditions, the concentration of Sm2O3 left in the raffinate (Nd group) was less than 0.1 wt% and the concentration of Eu2O3 in concentrated Sm Eu Gd oxides in the scrubbed organic phase was larger than 8.0 wt% (commercial grade). In the concentrating process of Nd group elements, the total RE concentration left in the raffinate was less than 0.1 g/L with a recovering efficiency more than 99%. The concentrated RE concentration was more than 250 g/L in the stripping raffinate and more than 14 times the feed concentration (17 g/L). The results show that the RPC has a great promise as an alternative of mixer‐settlers for saving space, solvent input, and operating (energy) cost in rare earth extraction and separation using the D2EHPA/RE2(SO4)3 system.