Rare Earth Elements In Environmental Samples Research Articles

A Feasibility Study of Rare-Earth Element Vapor Generation by Nebulized Film Dielectric Barrier Discharge and Its Application in Environmental Sample Determination.

The feasibility of 16 types of rare-earth elements (REEs) containing Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu vapor, generated simultaneously, was demonstrated by nebulized film dielectric barrier discharge (NFDBD) in this work. Note that this is the first report on the simultaneous vapor generation of 16 types of REEs, which previously was difficult to realize. Combining it with inductively coupled plasma-mass spectroscopy (ICP-MS) as the sampling technique, a 4-fold to 10-fold improvement in the detection limits (LODs) of the REEs was observed, compared with the conventional solution nebulization, and no obvious interferences from other metal ions and the mutual interferences between REEs at the mg L-1 level were found. Compared with ultrasonic nebulization, microconcentric (MCN) and membrane-desolvation (Aridus) and electrothermal vaporization (ETV) for REEs sampling, this NFDBD sampling technique operates not only with low cost and low power, but also without any requirement of extra reagents and easy coupling with flow injection for volume limited samples. Under optimized conditions, the relative standard deviation (RSD) of 16 types of REEs determined at 5 μg L-1 was between 0.2% and 1.9%, and the LODs of REEs were between 0.002 ng L-1 and 0.422 ng L-1, depending on the element. This technique provides an alternative green and highly efficient vapor generation approach for the determination of REEs in environmental samples, especially in natural water.

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.

Rare Earth Elements in Soils of Jharia Coal Field

There are many sources trough which the soil get enriched and contaminated with REEs. The determination of REEs in environmental samples has been limited because of the lack of sensitive analytical techniques. Soil samples were collected from four sites including open cast coal mine, natural coal burning, coal washery and control in the coal field located in Dhanbad, India. Total concentrations of rare earth elements (REEs) were determined using the inductively coupled plasma atomic absorption spectrometry in order to assess enrichment status in the coal field. Results showed that the mean concentrations of La, Pr, Eu, Tb, Ho, and Tm in open cast mine and natural coal burning sites were elevated compared to the reference concentrations, while Ce, Nd, Sm, and Gd were elevated in coal washery site. When compared to reference soil, heavy REEs (HREEs) were enriched in open cast mines and natural coal burning affected soils, however, the HREEs were depleted in the coal washery sites. But, the Chondrite-normalization diagram showed significant enrichment for light REEs (LREEs) in all the soils. High concentration of Pr, Eu, Tb, Ho, Tm, and Lu in coal mining and coal burning sites may pose human health risks. Factor analysis showed that distribution and relative abundance of REEs of the coal washery site is comparable with the control. Eventually washing or cleaning of coal could significantly decrease the emission of REEs from coal into the environment.

Speciation of rare earth elements in soil by sequential extraction then HPLC coupled with visible and ICP-MS detection.

The distribution of rare earth elements (REE) in a pooled soil sample collected from Zhangzhou, Fujian Province, China, was screened by a five-step sequential extraction procedure coupled with ICP-MS determination after preconcentration of REE and removal of the matrix by extraction with 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (HPMBP). The results showed that the distribution of REE in the different fractions of the pooled soil sample studied followed the order soluble species (46.76%) > species bound to organic matter (22.08%) > species in the residue (16.77%) > species bound to Fe-Mn oxides (2.02%). An effective method for speciation of REE, which utilized weak cation-exchange HPLC separation hyphenated with post-column derivatization and visible or on line ICP-MS detection, was, moreover, developed and successfully applied to the speciation of REE in the soluble extract of the pooled soil sample. The stability of known complexes of lanthanum during the HPLC separation was investigated with fluoride, citrate, and ethylenediamine tetraacetic acid (EDTA) chosen as ligands modeling those in the soil. REE in the soluble extract of the pooled soil sample were subsequently classified into three types of species--< or = +1 charged complexes (negatively charged, neutral, and +1 charged), +2 charged complexes, and "free" REE species. This method is expected to be useful for identification of bioavailable (or toxic) species of REE in environmental samples.

Determination of rare-earth elements in environmental samples

A procedure is suggested of extraction-chromatographic pre-separation of REE's for the next activation determination. This method was applied for analyzing geological samples, underground and surface water, some technological materials.