Preconcentration Of Rare Earth Elements Research Articles

Characterization and pre-concentration of rare earth elements in density fractionated samples from the Waterberg Coalfield, South Africa

The increased global demand for rare earth elements (REEs) from unconventional sources has led to increased interest and research in coal deposits. South Africa has extensive coal resources, but understanding of the concentration, mode of occurrence, and distribution of REEs in the coals and associated sediments is limited. This study aims to assess selected coal samples obtained from an exploration project underway in the Waterberg Coalfield (South Africa) to determine the concentration and mode of occurrence of REEs, and to gain insight into the behaviour of REEs during density fractionation. Density fractionation of coal is considered a pre-concentration method prior to REE extraction. Samples were selected from zones 8, 7, 4, and 3, spanning the Grootegeluk and Vryheid Formations of the Waterberg Coalfield. Density fractionation was conducted at relative densities (RD) of 1.3 to 1.8, providing float (F) and sink (S) products. Five parent and thirty density-fractionated coal samples were characterized using proximate analysis, petrography, X-ray diffraction (XRD), and the concentration of REEs determined using Inductively Coupled Plasma- Mass Spectrometry (ICP-MS) (after microwave digestion).The samples are classified as medium-rank C bituminous coals with variable maceral composition. The dominant minerals are kaolinite and quartz, occurring as both syngenetic and epigenetic phases. The total REY (REEs + yttrium) concentrations range from 45.1 to 389.2 ppm, higher than for world coals (except sample 8H F1.30, REY = 45.1 ppm), and generally higher than the average for Chinese coals. Float products obtained at 1.40 to 1.80 RD show greater variation of light REY (LREY) compared to medium REY (MREY) and heavy REY (HREY), whereas float fractions at 1.30 and sink fractions at 1.80 RD show no distinct enrichment patterns. Although the results suggest a relationship between the concentration of LREY with float fractions obtained between 1.40 and 1.80 RD, pre-concentration using density fractionation generally shows limited benefits for these coals. Ashing of the coals may be more effective in concentrating the REEs and further investigations are therefore required.

Preconcentration and ICP-OES determination of rare earth elements using silicas chemically modified with aminophosphonic groups in fossil raw materials

ABSTRACT Silica-based adsorbents (Silica gel 60 and Silochrom S-80) chemically modified with aminophosphonic groups with various surface concentrations have been proposed for the preconcentration of rare earth elements (REE). The resulting adsorbents were studied by FT-IR, SEM, TGA and compared with unmodified matrices. Adsorbents quantitatively extracted REE from solutions with pH 1.0–5.0. Solid phase extraction at pH 1.0–2.0 made it possible to quantitatively separate rare earth elements from the predominant amounts of accompanying metal ions. An increase in the concentration of aminophosphonic groups on the silica surface led to an increase in the adsorption capacity of the adsorbent for Gd(III) both in batch and dynamic modes. A technique for solid-phase extraction followed by inductively coupled plasma optical emission (SPE-ICP-OES) determination of REE has been developed; it includes pumping 200 mL of the sample solution (pH 1) through a mini-column with an adsorbent at a flow rate of 1 mL min−1, eluting REE with 10 mL of 1 M HNO3 (preconcentration factor 20), and then determination of the elements in the eluate by ICP-OES. The technique was used for the determination of REE in lignite and coal from the Krasnoyarsk Krai (Russia). The accuracy of the results was confirmed by comparison with ICP-MS determination and by the analysis of certified reference material of coal ash.

Eco-friendly dispersive liquid–liquid microextraction procedure based on solidification of floated organic drop coupled with back-extraction for preconcentration of rare earth elements

ABSTRACT In this study, a simple and efficient eco-friendly procedure for preconcentration of trace amounts of Y, Sm, Eu, Gd, Er and Yb was developed prior to determination by inductively coupled plasma optical emission spectrometry (ICP-OES). The extraction process involved two sequential steps. The first is based on ultrasonic-assisted emulsification solidified floating organic drop microextraction using morin and 1-undecanol as complexing and extraction agents, respectively. The analyte in the solidified floated organic drop was then back-extracted into aqueous solution of HNO3 to prevent the relapsing effect of the organic matrix on the performance of ICP-OES. The effect of various experimental parameters on the extraction efficiency was studied and optimised. The limits of detection were in the range of 0.053 (Y) – 0.086 (Sm) µg L−1 with linear dynamic analytical range of 0.3–1000 µg L−1 at the optimal conditions. The relative standard deviations (C = 20 µg L−1, n = 10) ranged from 1.7% (Eu) to 2.5% (Yb). Finally, the approach represented high efficiency in determining the rare earth elements in certified reference material and phosphite rock samples.

Modes of occurrence and pre-concentration of rare earth elements in No. 17 coal in Liupanshui coalfield, China

Rare earth elements (lanthanide and yttrium, abbreviated as REY) provide important support for national security, energy production, environmental protection and economic growth. In recent years, many studies have shown that the content of REY in some coal or coal by-products is close to or even higher than that in traditional REY ore, which makes coal a potential source of REY. This study took the No. 17 coal of Panzhou mining area in Liupanshui coal field as the research object, and the content and occurrence modes of REY in raw coal and 7 density fraction samples were studied. The results show that the content of REY in the raw coal reaches 220.67 μg/g, which is significantly higher than the average REY content in the world coal and Chinese coal as reported in the literature. Gravity separation has a certain pre-enrichment effect on REY and the fraction sample ＞1.8 g/cm3 has the highest REY of 426.27 μg/g (equal to rare earth oxide 0.1%). Study on correlation between REY and ash yields reveals that the organic affinity of the light rare earth is higher than that of the medium rare earth and the heavy rare earth. As shown by X-ray diffraction (XRD) and X-ray flouresence spectroscopy (XRF), the major minerals in coal are kaolinite, quartz and calcite, and the content of REY in coal is significantly related to Al, Si and kaolinite, which implies that REY occur mainly in kaolinite. Laser ablation inductively coupled plasma mass spectroscopy (LA-ICP-MS) was adopted to determine chemical composition of micro-zone in kaolinite in coal and the results show that there is no obvious correlation between REY and the contents of Al and Si. This indicates that the REY occur probably in the form of adsorption. The research results provide a scientific reference for the potential extraction of the associated REY in the coal.

Dual column HPLC method for determination of lanthanides in zirconium matrix

A high performance liquid chromatography (HPLC) method is developed for the determination of lanthanides present in zirconium matrix. α-Hydroxyisobutyric acid (α-HIBA) is used as an eluent for the removal of bulk of zirconium and pre-concentration of lanthanides. Later the pre-concentrated lanthanides are individually separated by dynamic ion exchange method. The method offers linearity in the concentration range of lanthanides from 2 to 100 ppb. The developed methodology is validated by analyzing simulated zirconium sample containing known amounts of lanthanides. The method is then used for quantitative recovery and determination of lanthanides in ZrO2 matrix with Zr/Ln amount ratios up to 250,000.

The genesis of regolith-hosted rare earth element and scandium deposits: Current understanding and outlook to future prospecting

Rare earth elements (REE) and scandium (Sc) have become strategical and critical resources to nations worldwide. Currently, regolith-hosted REE deposits in South China and the neighbouring regions provide more than 90% of the global heavy REE (HREE) production. Recent discoveries highlight the potential of exploitable Sc resources from regolith-hosted deposits. Hence, knowledge about the nature and ore-forming processes of these REE and Sc deposits is important to facilitate identification of favourable geological and geomorphological environments and thus to guide exploration of these deposits. Previous studies have confirmed that felsic and mafic-ultramafic rocks are favourable parent rocks for the formation of REE and Sc deposits, respectively. Apparently, these parent rocks are already enriched in REE and Sc, both geochemically and mineralogically, during their petrogenesis. Favorable protolith for the formation of regolith-hosted REE deposits includes granites, syenites, and volcanic rocks with most of the REE hosted in weathering susceptible minerals, for example, synchysite, gadolinite, and hingganite for the HREEs, and allanite, titanite, apatite for the LREEs. Clinopyroxene-rich mafic-ultramafic rocks are ideal protolith for the formation of regolith-hosted Sc deposits. During weathering, REE are liberated during decomposition of the parental minerals and mainly sorbed on clay minerals, notably kaolinite and halloysite. A critical transformation from poorly crystallized, nano-sized halloysite and kaolinite to much more crystalline and larger vermicular kaolinite is observed with progressive weathering. Adsorption capacity of the clay minerals significantly decreases in this transformation, thereby, REE adsorption becomes unfavorable and desorption dominates in the shallow soils, whereas efficient adsorption on the clay minerals could take place in deep regolith. Weathering behavior of Sc is different from the REE. A case study from Australia reveals that Sc is initially sorbed on smectite after decomposition of parental Sc-rich clinopyroxene. Subsequently, Sc is sorbed on neoformed Fe oxyhydroxides, thereby efficiently retain in the shallow Fe-rich duricrust, when smectite is dissolved in more advanced weathering. Mobilization, re-distribution, and accumulation of REE and Sc to form deposits are closely related to the groundwater flow and adsorption-desorption processes of these elements on the supergene minerals. Transport of REE would be dominated as free cations in shallow, acidic soils but the importance of REE-carbonate complexes dramatically increase with depth, facilitating the mobilization of HREE. Moreover, external elemental input from local groundwater would result in precipitation of supergene REE minerals, for example chernovite-(Y) at the Zudong deposit in South China. Supergene processes are key in controlling the formation and preservation of ore bodies. Alternating episodes of intense and weak erosion are favourable to form giant regolith-hosted deposits, whereas an equilibrium state between weathering and erosion also plays a role in the ore formation. Intense erosion would accelerate chemical weathering and liberation of REE and Sc from the protolith for ore formation, whereas intervals of minimal erosion are also required for preservation of thick ore bodies. Pre-concentration of REE and Sc in parent rocks, and favourable supergene environments for the ore formation and preservation remain for further studies. Key scientific questions awaited to be solved include the petrogenesis of geochemically and mineralogically favorable protolith as ground preparation for the supergene ore formation and the concentration mechanism of REE and Sc in this process. Moreover, it is crucial to decipher the occurrence of REE and Sc in different clay minerals and Fe oxyhydroxides in these deposits, and the associated sorption-desorption mechanism. Application of visible light-infrared spectroscopy to the exploration of regolith-hosted REE and Sc deposits deserves particular attention in the future endeavour.

Assessment of the leaching potential of flotation tailings from rare earth mineral extraction in cold climates

Increasing use of rare earth elements (REEs) in modern technologies and existing or expected imbalances between demand and supply have led many countries, including Canada, to consider the exploitation of their own REEs primary sources. The objective of this study is a thorough characterization of the flotation tailings generated during the pre-concentration of REEs from a carbonatite type deposit with the aim of predicting their geochemical behaviour over time. These tailings were characterized based on physicochemical and mineralogical properties. Weathering cells were also used to assess the impact of temperature (3 and 19 °C) on the geochemical behaviour of the tailings exposed to a sub-arctic climate. Because the tailings consisted mainly of carbonates (97.4%) and had very high neutralization potential (859 kg CaCO3/t) relative to their acidity potential (3.94 kg CaCO3/t), no acid mine drainage (AMD) is anticipated. Compared to regional environmental standards and guidelines, the concentrations of Cd (0.20 μg/l), Zn (17 μg/l), and Pb (close to 4 μg/l) in leachates obtained during kinetic testing may be considered as potentially problematic. Finally, the results of the weathering cells at 3 °C indicate that the exposure to low temperatures may increase the concentrations of elements leached from the tailings. This study confirms that low temperatures and freeze-thaw events, which occur readily in a sub-arctic climate, may impact the geochemical behaviour of tailings produced from the extraction of REEs from carbonatite type deposit.

Polyethylenimine-modified chitosan materials for the recovery of La(III) from leachates of bauxite residue

The separation and recovery of rare earth elements (REEs) from leachates of bauxite residue has attracted increasing attention. Yet, the characteristics of bauxite residue leachates (low pH, low concentration of REEs, and co-existence of other trivalent ions) results in a longstanding challenge in the recovery of REEs. Here, we reported on the development of polyethylenimine (PEI) modified chitosan materials as efficient adsorbents for REE, La(III). The introduction of PEI brought abundant protonatable amino nitrogen atoms, which endows materials with excellent buffering capacity at extremely acidic pH. The PEI-chitosan materials can easily separate La(III) from Al(III), a major co-existing ion, with a separation factor of 3.1. The single-metal adsorption behavior showed fast and efficient adsorption capacity of 2.015 mmol/g for La(III). In binary systems, La(III) was preferentially adsorbed over Al(III) due to the higher degree of association with PEI. The FT-IR, XPS and EDS mapping results revealed that in the binding mechanism the N atoms form coordination bonds with La(III) by sharing an electron pair, resulting in eight-membered chelate rings. The PEI-chitosan materials also exhibited an excellent reusability with regeneration efficiency of 90% after 4 recycles. Overall, PEI-chitosan demonstrates that it is a viable and economical material for the separation and preconcentration of REEs from leachates of bauxite residue.

Size-Selective Separation of Rare Earth Elements Using Functionalized Mesoporous Silica Materials

The separation and preconcentration of rare earth elements (REEs) from mineral concentrates in an economically and environmentally sustainable manner are difficult tasks due to their similar physicochemical properties. Herein, a series of tetradentate phenylenedioxy diamide (PDDA) ligands were synthesized and grafted on large-pore three-dimensional KIT-6 mesoporous silica. In solid-phase extraction, the hybrid sorbents enable a size-selective separation of REEs on the basis of the bite angles of the ligands. In particular, smaller REE3+ ions are preferentially extracted by KIT-6-1,2-PDDA, whereas light REEs with larger ionic radius are favored by KIT-6-1,3-PDDA. The exposure of bauxite residue digestion solution containing REEs as well as a number of types of competitive ions (including Th and U) to the sorbents results in selective recovery of target REEs. The possibility of regenerating the mesoporous sorbents through a simple loading-stripping-regeneration process is demonstrated over up to five cycles with no significant loss in REE extraction capacity, suggesting adequate chemical and structural stability of the new sorbent materials.

High-capacity extraction chromatographic materials based on polysulfone microcapsules for the separation and preconcentration of lanthanides from aqueous solution

Extractant-loaded polysulfone (PS) capsules suitable for the separation and preconcentration of rare earth ions from acidic media have been prepared and characterized. Specifically, PS macro- and microcapsules have been impregnated with bis(2-ethylhexyl)phosphoric acid (HDEHP), and their performance in the extraction of europium (Eu3+) from nitric acid solution evaluated. The HDEHP-loaded microcapsules were found to exhibit sorption efficiency superior to those of analogous macrocapsules. Comparison to a conventional (i.e., commercial) extraction chromatographic (EXC) material (Ln•Resin), comprising HDEHP-loaded beads of poly(methyl methacrylate) (PMMA) of comparable size (50–100 µm), showed that the capacity of the HDEHP-loaded microcapsules for europium is ca. 2.5-fold greater than that of the conventional material. This larger capacity is the apparent result of both the higher extractant loading achievable with the microcapsules and an unexpected change in the complexation stoichiometry of europium by HDEHP upon extractant encapsulation. The microcapsule-based sorbent equaled or exceeded the performance of the commercial EXC material in other respects as well, most notably uptake kinetics and column efficiency, making it a promising alternative to established EXC resins.

Diglycolamide-grafted Fe3O4/polydopamine nanomaterial as a novel magnetic adsorbent for preconcentration of rare earth elements in water samples prior to inductively coupled plasma optical emission spectrometry determination

In this work, magnetic nanomaterials were synthesized by grafting diglycolamide (DGA) derivatives onto polydopamine (PDA) functionalized magnetic nanomaterials (Fe3O4@PDA@DGA). The adsorption behaviors of Fe3O4@PDA@DGA for rare earth elements (REEs) were evaluated. The characterization results indicated that the Fe3O4 nanoparticles form a hexagonal-like two-dimensional projection shape, and DGA is successfully grafted onto the surface of the nanomaterials. By using Fe3O4@PDA@DGA nanomaterials as the adsorption material, a novel method for magnetic solid phase extraction (MSPE) coupled with inductively coupled plasma optical emission spectrometry (ICP-OES) was developed, which can quantitatively determine trace REEs in environmental water. With the MSPE procedure, the parameters affecting the adsorption behaviors of the REEs on Fe3O4@PDA@DGA nanomaterials, such as pH, ultrasonic adsorption time, mass and solution volume were investigated systematically. Under the optimum experimental conditions, the limits of detections (LODs) and the relative standard deviations (RSDs) of 16 REEs (C = 10 µg L−1, n = 7) were in the range of 0.039 µg L−1 for Eu to 0.425 µg L−1 for Nd and 1% for La to 3.9% for Gd. The linear range of the calibration curve over 2–1000 ng mL−1 (R2 > 0.999) was obtained for the target analytes. This developed method was applied for the environmental samples and the recoveries were 95.8–105.8% for the spiked water. The proposed MSPE-ICP-OES method has the advantages of easy separation, simple operation, good anti-interference capability, fast adsorption and elution kinetics, low detection limits, high sensitivity and fast analysis speed, thereby acting as a potential application for the simultaneous analysis of trace REEs in environmental samples.

Silica-supported pyrolyzed lignin for solid-phase extraction of rare earth elements from fresh and sea waters followed by ICP-MS detection.

Silica-supported pyrolyzed lignin (pLG@silica) was investigated as a solid sorbent for the pre-concentration of rare earth elements (REE) from natural waters followed by inductively coupled plasma mass spectrometry (ICP-MS) analysis. The carbon-based material was easily prepared by pyrolytic treatment of lignin at 600°C after its adsorption onto silica micro-particles. pLG@silica was characterized by scanning electron microscopy (SEM), surface area measurements (BET method), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), point of zero charge measurement, and X-ray photoelectron spectroscopy (XPS). The as-prepared material (50mg) was tested as fixed-bed sorbent for the solid-phase extraction (SPE) of tap, river, and sea water samples spiked with REE in the 10-150ngL-1 range, followed by ICP-MS analysis. A quantitative adsorption was observed for all REE with recoveries in the range of 72-118%. A suitable inter-day precision (RSDs 5-12%, n = 3) was obtained. Sample volumes up to 250mL provided enrichment factors up to 100. The method detection and quantification limits (MDLs and MQLs) were in the range of 0.4-0.6ngL-1 and 1-2ngL-1, respectively. The batch-to-batch reproducibility was verified on four pLG@silica independent preparations. As remarkable advantages, pLG@silica proved to be of easy preparation using a waste material, inexpensive, and reusable for at least 20 SPE cycles.

Investigation of adverse effect of coexisting aminopolycarboxylates on the determination of rare earth elements by ICP-MS after solid phase extraction using an iminodiacetate-based chelating-resin

When iminodiacetic acid chelating-resin solid phase extraction (SPE) was used for the preconcentration of rare earth elements (REEs) in river water samples around sewage treatment plant (STP), low recovery values for heavy REEs were observed. In order to find out the reason for the low recovery, in the present paper, organic ligands in the STP effluent, which may compete with iminodiacetic acids, were analyzed by GC-NPD. It was found that EDTA was contained in the STP effluent at several-100 nM level and interfered with the adsorption of REEs, especially heavy REEs (present at pM level) on the chelating-resin due to the formation of stable complexes. Therefore, acid treatment was applied to decompose EDTA molecules. As a result of acid treatment with HNO3 and H2O2 at 170 °C for 4 h, all REEs were almost quantitatively recovered from the STP effluent with chelating-resin SPE with good reproducibility. After the acid treatment and subsequent 40-times preconcentration with SPE, all REEs in river water samples were precisely determined by ICP-MS at several-10 to sub pg mL−1 levels.

Calcium alginate microparticles for rare earth elements preconcentration prior to ICP-MS measurements in fresh water

Calcium alginate microparticles were used for the preconcentration of rare earth elements for ICP-MS analysis of fresh waters.

Comments on: Simultaneous Separation and Preconcentration of Rare Earth Elements on Activated Carbon for its Determination by ICP-OES in Beneficiation Products

Comments on simultaneous separation and preconcentration of rare earth elements on activated carbon/charcoal for its determination by ICP-OES in beneficiation products and different geological matrices has been presented. The manuscript published on benefication products is lacking in any innovation, originality or novelty over the earlier published paper titled “Determination of Rare earth elements in different geological matrices by ICP-AES after solid phase micro extraction on activated charcoal” by Murty, Mohanta and Radhamani published in the journal, Atomic Spectroscopy. There is a repetition of the “The unique feature of the method’ in the above cited manuscript and also in his earlier publication titled “A single stage simultaneous separation and preconcentration of rare earth elements on activated carbon for its determination by ICP-OES after wet ashing–application to soil samples by Chakrapani, Mahanta, Hanuman, Srivastava published in the journal “Exploration and Research for Atomic Minerals on bromoheavies. Moreover, there are contradictory and misleading statements /findings on the role of AC as adsorbent, amount of AC and desorption of REEs from AC in the published papers by Chakrapani et al. [1] and other authors from AMD laboratories. The findings have previously published elsewhere without proper cross referencing /justification in manuscripts. The desorption of REEs from AC simply by treating AC with 3.2 M HNO3 is the best analytical protocol, thus avoiding the tedious and time consuming operation of ashing AC. Moreover, regenerated AC can be re-used for further experiments. Dry-ashing of the charcoal pellet is the alternate option and can be completed in 1 hr. Wet-ashing of charcoal pellet with HNO3 and HClO4 involves toxic acids fuming, is a health hazard and may lead to serious explosions. Separation of rare earth metals through biosorption using low cost biomaterials or modified AC will continue to remain a greatest challenge.

Separation and preconcentration of rare earth elements in geological materials using used tea leaves and their determination by ICP-OES

Separation and preconcentration of rare earth elements in geological materials using used tea leaves and their determination by ICP-OES

Sorbents with non-covalently immobilized β-diketones for preconcentration of rare earth elements

A comparison of the efficiency of sorbents obtained by different methods of non-covalent immobilization of β-diketones on some low-polar matrices with respect to extraction of rare earth elements (REEs) was carried out. It was shown that sorbents containing reagent amounts of 1–8mmol/g can be obtained by sorption of reagents on low-polar matrices from aqueous and aqueous-organic solutions, and the value for the maximum capacity of the sorbent correlates with the specific surface of the matrix. Similar sorbents were also prepared by impregnating the matrix with reagent. It was found out that, under the chosen conditions, sorbents modified by extracting reagent from the aqueous solutions are more stable and extract lanthanum with higher distribution coefficients than those obtained by impregnation. We have found conditions for quantitative extraction of REEs from seawater in the proposed preconcentration systems (pH 4.0, minicolumn dimensions 2×10mm, v=4ml/min). It was shown that all REE may be quantitatively recovered in both ways: on modified sorbents and as complexes with reagents on unmodified matrices. We have proposed a sorbent for lanthanum preconcentration from large volumes of water samples (500ml). The sorbent is stable in dynamic conditions and is based on hyper cross-linked polystyrene modified with 1-phenyl-3-methyl-4-benzoylpyrazol-5-one (PMBP). Desorption could be carried out with 1–2M HNO3. REEs were determined by ICP-MS, LODs achieved were in ng/l range.

Preparation, characterization and application of Saussurea tridactyla Sch-Bip as green adsorbents for preconcentration of rare earth elements in environmental water samples

This paper deals with preparation, characterization and application of the Saussurea tridactyla Sch-Bip (STSB) as a new green adsorbent for separation of matrix elements and preconcentration of rare earth elements (REEs) in environmental water samples. The pretreated STSB adsorbent with 2molL−1 NaOH is characterized with higher surface area and adsorption capacities in comparison with a raw STSB material. The new adsorbent was used for the development of on-line solid phase extraction (SPE) for the determination of REEs by radial viewing 27MHz inductively coupled plasma optical emission spectrometry (ICP-OES). Various parameters affecting the adsorption/desorption procedure were optimized. The adsorption capacities for the STSB were found to be 62.2 (Y)–153mgg−1 (Tm). Under the optimized conditions, the limits of detection (LODs, 3σ) for REEs were in the range of 0.06 (Yb)–8.77 (Sm) ngmL−1. The relative standard deviations (RSDs) for 7 replicate determinations of target REEs at low concentration level ranged from 2.4 (Yb) to 8.9 (Sm)%. The adsorption isotherm fitted Langmuir model and the adsorption kinetics fitted well with both Pseudo-first order and Pseudo-second order models. The predominant adsorption mechanism is ion exchange. The STSB pretreated with 2molL−1 NaOH has been demonstrated to be low cost, green and environment friendly adsorbent, featuring with high adsorption capacity, wide pH range, and fast adsorption/desorption kinetics for target REEs with long lifetime. The proposed method was applied to the determination of REEs in East Lake, Yangtze River and rain water samples.

On-line Green Solid Phase Extraction of Trace Rare Earth Elements and Uranium in Environmental Samples and ICP OES Detection

An on-line solid phase extraction (SPE) method using mini column packed with natural sorbent based on cotton roll dyed by quinalizarin was developed for simultaneously pre-concentration of rare earth elements and uranium at trace levels in environmental samples followed by inductively coupled plasma optical emission spectrometry (ICP OES) determination. Various parameters such as sample and eluent flow rate, sample volume and matrix ions on the method efficiency have been investigated. Under the optimized conditions, the limits of detection (LODs, 3σ) for rare earth elements were in the range of 0.002-0.300 µg L-1 and 0.420 µg L-1 for uranium. The relative standard deviation (n = 5) were lower than 6% except for samarium and uranium. The method was successfully applied for determination of trace rare earth elements and uranium in lake, well, tap water and carbonate mineral samples. The accuracy of the proposed method was validated by add-found method and direct analysis by ICP OES. This method has some advantages such as simplicity, rapidity, green chemistry and high sensitivity.

Bioparticles coated with an ionic liquid for the pre-concentration of rare earth elements from microwave-digested tea samples and the subsequent quantification by ETV-ICP-OES

An analytical procedure for straight-forward quantification of rare earth elements (REEs) in tea was developed.