Comparative study on rare earth elements from Flos Sophorae and Fructus Sophorae

Flos Sophorae and Fructus Sophorae are two kinds of traditional Chinese medicines. In this work, the two kinds of traditional Chi-nese medicines collected from eleven areas of Dezhou, were analyzed by inductively couple plasma-mass spectrometry (ICP-MS) to compare the content and distribution of 14 kinds of rare earth elements (REEs). The method was verified by analyzing GBW07605 certified reference material. The results showed that ICP-MS is an accurate, sensitive and reliable technique for determining REEs in traditional Chinese medi-cine. There were big differences in contents for REEs in Flos Sophorae and Fructus Sophorae from different areas. The contents of total REEs in Flos Sophorae samples from different areas ranged from 1.0785 to 2.2659 g/g, while those in Fructus Sophorae from 0.6826 to 1.0527 g/g. The contents of total REEs in Flos Sophorae samples from different areas were obviously higher than those in Fructus Sophorae of the same area and there was big difference between various Flos Sophorae samples. Interestingly, the higher the content of total REEs in Flos Sophorae samples, the lower the content of total REEs in Fructus Sophorae samples of the same area. The plots of normalized element con-centration versus atomic number showed some characteristic distribution trends. The distribution trend of light REEs (La-Gd) was relatively flat except a positive Eu anomaly, however, that was steep and discrepant for heavy REEs (Tb-Lu). The results could provide a valuable ref-erence for understanding the relationship between the curative mechanism, pharmacology characteristics and their geological condition for the two traditional Chinese medicines investigated.     

La,Ce,Pr,Nd and Sm concentrations in Pu'er tea of Yunnan,China

The rare earth elements contents (La, Ce, Pr, Nd, Sm) in 150 Pu'er tea samples were analyzed by using inductively coupled plasma atomic emission spectroscopy (ICP-AES), to evaluate the safety of Pu'er tea. Among the investigated rare earth elements (REEs), Ce was the highest (35% of the total REEs content) whose concentrations were found to be in the range of 0.11–1.39 mg/kg, whereas that of Sm in the range 0.01–0.21 mg/kg, showing minimum levels (5.2%). La was the second highest element (28%) found in Pu'e...     

Rare earth elements in flotation products of coals from East Kootenay coalfields,British Columbia

With the identification of coal deposits that are enriched in rare earth elements (REEs) across the world, coal and coal by-products are considered as an alternative source for REEs due to the combined supply and demand restrictions for these elements. Studies are being conducted to recover these elements from various coal sources. In this study, coal samples from the East Kootenay coalfields in British Columbia, Canada were examined for the presence of REEs in run-of-mine coal samples and flotation products.Results reveal that on an ash basis, the concentration of REEs varies from 174 to 1038 mg/kg in the samples. To understand the REE as sociation, which is essential for extraction purposes, a three-step sequential extraction process along with a mineralogical evaluation using scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX) and quantitative X-ray diffraction (XRD) data was used. It is found that a significant portion of REEs in the feed samples were reported to middling and tailings streams. The mineralogical analyses reveal REE association with aluminosilicate mineral in the samples.     

Effects of the accumulation of the rare earth elements on soil macrofauna community

The accumulation of rare earth elements(REEs)in soil has occurred due to the pollution caused by the exploitation of rare earth resources and the wide rare earth fertilizers in agriculture.The accumulation of REEs has a toxic effect on the soil macrofauna community.12study samples were collected near a mine tailings dam with a large amount of REEs by distance gradient sample method.The total concentration of REEs was analyzed and the results were compared with that of the sample from a control site.The effects of the amount of REEs in the soil on the soil macrofauna community were also analyzed.The results showed that the accumulation of REEs in soil was significant in the study area and its concentration was strongly correlated with the distance from the pollution source.One-way ANOVA analysis indicated the significant differences in soil macrofauna communities among the different sites.The ordination obtained through the redundancy analysis demonstrated that the concentration of REEs and the total nitrogen,total potassium and pH,had affected the soil macrofauna community.A small amount of REEs in the soil can promote the diversity of soil macrofauna,but a large amount of REEs can reduce its diversity.The insect groups of Carabidae and Dermaptera were comparatively sensitive to the concentration of REEs in soil,and could be used as an indicator of soil pollution of REEs.However,the Formicidae and Stibaropus formosanus exhibited a high tolerance to REEs in soil.We believe that it is very important for the soil environment protection to strictly control the application of the rare earth fertilizers in agriculture in China.     

Geochemical Characteristics of Rare Earth Elements in Intertidal Sediments of Tianjin Coastal Zone

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不同降雨条件下城市路尘中稀土元素流失特征

通过对包头市路尘中14种稀土元素(rare earth elements,REEs)含量的测定分析以及小型人工降雨冲刷模拟,对稀土元素在路尘中的赋存特征及在其降雨径流中的流失特征进行了分析和探讨。结果表明,(1)路尘中的稀土元素随降雨过程发生迁移并在径流产生"流失浓缩"效应,浓缩强度随雨强增加而增强;相同雨强下,水泥下垫面的聚集效应高于沥青混凝土下垫面。(2)径流中水相稀土元素含量随降雨时间下降。(3)径流流失过程中,固相颗粒态中稀土元素的配分模式与路尘样品基本一致,呈现轻稀土富集的特征,轻重稀土之间的分馏程度较高;而水相中稀土元素的配分模式与原始路尘样品中有一定差异,轻重稀土之间的分馏程度降低。     

Precipitation-dissolution behaviors of rare earth ions in H_3PO_4-Ca(H_2PO_4)_2 solutions

In order to achieve deeper understanding of rare earth elements(REEs) behaviors during phosphate rock processing with H_3PO_4. The solubility of REEs in Ca(H_2PO_4)_2-H_3PO_4 solutions with various concentrations of Ca(H_2PO_4)_2 at different temperatures were tested. The results demonstrate that REEs solubility decreases sharply with the increasing concentration of Ca(H_2PO_4)_2. Equations between [REE~(3+)] and [H~+],[H~+] and [Ca~(2+)] in Ca(H_2PO_4)_2-H_3PO_4 solutions were built based on the precipitation-dissolution equilibrium of rare earth phosphates and the ionization equilibrium of H_3PO_4. According to the equations, the decreasing mechanism of REEs solubility caused by elevated concentration of Ca(H_2PO_4)_2 was determined. The mechanism can be illustrated as that the elevated concentration of [H_2 PO_4~-] decreases the concentration of hydrogen ion by retarding the ionization process of H_3PO_4 and directly promotes the precipitation of rare earth phosphates. Furthermore, it can be easy deduced that similar effect would be caused by the other cation impurities(Fe~(3+), Al~(3+), etc.) on REEs solubility based on the mechanism. In addition, superimposed reduction effect on REEs solubility caused by the elevated concentration of Ca(H_2PO_4)_2 and the elevated temperature is found. This superimposed effect leads to a super low solubility of REEs in Ca(H_2PO_4)_2-H_3PO_4 solution. On the basis of the experimental study, outlooks and suggestions for further development of REEs recovery method are given.     

Geochemistry of rare earth elements in cobalt-rich crusts from the Mid-Pacific M seamount

Rare earth elements (REEs) and major elements of 25 cobalt-rich crusts obtained from different depths of Mid-Pacific M seamount were analyzed using inductively coupled plasma-atomic emission spectrometer and gravimetric method. The results showed that they were hydrogenous crusts with average ∑REE content of 2084.69 μg/g and the light REE (LREE)/heavy REE (HREE) ratio of 4.84. The shale-normalized REE patterns showed positive Ce anomalies. The total content of strictly trivalent REEs increased with water depth. The Ce content and LREE/HREE ratios in Fe-Mn crusts above 2000 m were lower than those below 2000 m. The change in REE with water depth could be explained by two processes: adsorptive scavenging by setting matters and behaviors of REE in seawater. However, the Ce abundance took no obvious correlation with water depth reflects the constant Ce flux. The Ce in crusts existed mainly as Ce(IV), implying that the oxidative-enriching process was controlled by kinetic factors.     

Vertical distribution of rare earth elements in a wetland soil core from the Sanjiang Plain in China

The objective of this study was to investigate the vertical distribution of rare earth elements (REEs) in a natural wetland soil core to understand the influence of natural and anthropogenic activities on geochemical behavior of REEs. A natural wetland soil core of 95 cm was collected from the Sanjiang Plain in China and sliced into 5 cm slices for analyses of REEs, Fe, Al, Mn, Sc, Y, and soil organic matter (SOM). Results indicated that SOM was accumulated in the upper part of the soil core (0 to 20 cm depth), while Fe and Mn was reductively leached from the upper part of the soil core and accumulated in the low part. The content of total REEs ranged from 137.9 to 225.9 mg/kg in the soil core. Content profiles obtained for all REEs were almost identical except for Ce. The highest contents of REEs generally occurred at about 20 cm depth, but enrichment factor (EF) of REEs except Ce was usually the highest in the surface horizon. Average EF ranged from 1.1 for La to 2.1 for Gd. The pronounced shift in EF occurred at about 40 cm depth and it gradually increased from 40 cm depth to surface (except for Ce), probably suggesting anthropogenic atmospheric deposition of REEs. In comparison with chondrite, Eu was depleted in all horizons, while Ce was negatively anomalous in the top horizons and positively anomalous in the bottom horizons. This positive anomaly of Ce in the bottom horizons was due to its preferential adsorption on Fe and Mn oxides, relative to other REEs. Although both natural and anthropogenic activi-ties influence the geochemical behaviors of REEs in soils, enrichment or mobility of REEs is low in the natural wetland soil core of the San-jiang Plain.     

Rapid recovery of rare earth elements in industrial wastewater by CuFe2O4 synthesized from Cu sludge

This study systematically evaluates the recovery of rare earth elements (REEs) from aqueous solution and industrial wastewater using magnetic nanoparticles CuFe₂O₄. The industrially manufactured CuFe₂O₄ displays a nonlinear isotherm for REEs adsorption, suggesting limiting binding sites on the CuFe₂O₄ surface. The recovery of REEs increases significantly from 0.1% to 99.99% with increasing pH (2.29–8.15). At room temperature, the maxima recovery rates of Nd, La, and Ce are observed to be in a high capacity of 51.02, 42.02, and 40.16 mg/g, respectively. No significant attenuation of REE adsorption is observed with increasing NaCl concentration from 0.001 to 1.0 mol/L, showing high selectivity of REEs even in such high NaCl concentration matrix. In addition, desorption efficiency increases with the increasing concentration of HNO₃ in the range of 0.005–0.05 mol/L. When HNO₃ concentration is over 0.05 mol/L, the desorption efficiency can reach almost 100% in each batch experiment. Importantly, our results show that REEs can be sorbed and recycled from liquid crystal display (LCD) polishing wastewater, suggesting that CuFe₂O₄ may be a good candidate in the efficient and rapid recovery of REEs from industrial wastewater.     

Recovery of thorium and rare earths from leachate of ion-absorbed rare earth radioactive residues with N1923 and Cyanex® 572

Ion-absorbed rare earth ores radioactive residues (IREORR) are a class of waste residue from the production of rare earth elements (REEs). Because of its radioactive dose, IREORR are usually stored in waste warehouses. IREORR are difficult to be disposed of. However, it contains relatively high concentrations of REEs, which can be considered as a valuable secondary resource. In this paper, a novel process is developed for the separation of thorium (Th) and recovery of REEs from IREORR hydrochloric acid leachate with primary amine N1923 and Cyanex® 572, respectively. The effects of sulfate concentration, extractant concentration and pH on N1923 extraction in hydrochloric acid solution were investigated in detail. The results show that the extraction capacity of N1923 can be improved by adding sulfate to the solution and increasing the concentration of N1923. Acidity has little effect on the extraction of Th when pH is higher than 1. As for the stripping, REEs are more easily stripped from loaded organic phase than Th, and nitric acid is a better stripping agent than hydrochloric acid. Combined with the extraction of Cyanex® 572 for REEs, a fractional extraction experiment for separating Th and enriching of REEs was performed. The yield of Th is higher than 99.9% and the concentration of REEs is enriched to 183.84 g/L.     

REEs fractionation and sedimentary implication in surface sediments from eastern South China Sea

To get features of rare earth elements(REEs)fractionation,106 surface sediment samples from eastern South China Sea were determined for REEs combined with major and trace elements by ICP-MS.The distribution pattern of REEs,strong correlation between REEs and Al,North American shale composite(NASC)normalization all suggest a dominant crustal source for REEs in the research area.However, distinct fractionation among REEs was observed in surface sediment from area with water depth over 2000 m,confirmed by the strong positive correlation among light rare earth elements(LREEs)and among heavy rare earth elements(HREEs)but weaker relationship between LREEs and HREEs.Eluviation by Cl – might be a key role on the fractionation of REEs,comparing with factors such as grain size,co-precipitation with Fe and Mn hydroxide,calcareous and siliceous biogenic precipitation.The fractionation among REEs could be used as index to illustrate the sedimentary environment in reverse.     

Simultaneous recovery of rare earth elements and phosphorus from phosphate rock by phosphoric acid leaching and selective precipitation:Towards green process

Phosphate rock has been considered as one of the potential promising resources for rare earth elements(REEs). But the cost issues and the technical challenges caused by the low content of REEs in ores did hinder the further development of REEs recovery technologies. In order to explore a green process for the recovery of REEs from phosphate rock, this study investigates the effects of phosphoric acid concentration, liquid-to-solid ratio(L/S ratio), leaching time and temperature on the leaching efficiencies of the major components from phosphate rock. A REEs recovery of 94.3% and a phosphorus recovery of 95.3%are achieved under the optimal conditions of attacking phosphate rock using 30%P_2 O_5 acid with an L/S ratio of 10:1 and a stirring speed of 250 r/min at 25 ℃ for 4 h. Then,the selective precipitation of REEs with 81.3% REEs recovery is realized by heating up the leaching solution from 25 to 90 ℃ and keeping for4 h. Thereafter, more than 95% phosphoric acid is recovered by H_2 SO_4 and high purity gypsum, more than95% CaSO_4(tested by XRF), is also produced at the same time. Ultimately, a green process that leaches phosphate rock with H_3 PO_4, selectively precipitates REEs from leaching solution by heating up, recovers H_3 PO_4 with H2 SO4 is proposed. Compared with REE recovery in traditional processes, this process owns the merits of simple operation, energy saving and minimum wastes.     

Dissolved rare earth elements estimation of ion-absorption rare earth ores using reflectance spectroscopy in south Jiangxi province,China

Ion-absorption rare earth ores are an important mineral resource in China. Nowadays, the unauthorized mining has become a serious problem, resulting in severe water pollution and the wastage of rare earth elements (REEs). Being able to estimate the concentration of dissolved REEs in water bodies near mines is essential for tackling this environmental problem. Conventionally, quantitative analyses of the contents of dissolved REEs are performed using laboratory-based techniques, which can be time consuming and costly. Spectral reflectance is a rapid and cost-effective means of characterizing the chemical compositions of light-absorbing materials. In this study, reflectance spectroscopy was performed on dissolved REEs, and the correlation between their reflectance characteristics and REE content was determined. A total of 50 aqueous media samples collected in south Jiangxi Province and 25 laboratory-produced aqueous media samples were tested, and their reflectance spectra and REE contents were measured using reflectance spectroscopy and inductively coupled plasma mass spectrometry, respectively. Next, the reflectance, differential reflectance, and absorption depth were analysed based on the REE content. Six diagnostic absorption features related to REEs are recognised in the visible and near-infrared wavelength regions, along with several smaller peaks. It indicates that the results of the absorption depth analysis are in accordance with the absorption spectra characteristics of the REEs, with the R² value being higher than 0.97. The intensity of each of the six absorption bands exhibits a linear correlation to the total REE content. Therefore, linear regression models can be derived for estimating the total concentration of REEs in aqueous media samples. What's more, the detection limit for REEs is determined to be about 30 μg/L. Thus, it can be concluded that reflectance spectroscopy is a suitable technique for estimating the concentration of dissolved REEs.     

枫香中稀土元素含量区间谱图的测绘与药性分析

应用ICP-MS测定了海南中部山区野生枫香中稀土元素的含量,讨论了其分布区间尺度,稀土元素总含量中占有最大比值的是Ce,为33.14%,其次是La\,Nd.绘制了含量区间谱图.枫香中稀土元素的含量区间位于4.5～7.0μg/g之间,波形平缓,波幅小,可推断其为辛味药性.     

Rare earth element content in the SPM of Daliao river system and its comparison with that in the sediments, loess and soils in China

Content and distribution patterns of rare earth dements （REEs） in the suspended particulate material （SPM） of Daliao River system were investigated and compared with those in the fiver and sea sediments, loess, and soils of China. Twenty-seven samples of SPM were taken in Daliao River system and digested with various acids followed by ICP-MS analysis for REEs and ICP-OES analysis for Al, Fe, Mn, Ti, Mg, Ca, Na, and K, to measure the total concentrations of these elements. Results indicated that the spatial change in the content of REEs was great, with the coefficient of variance （CV） from 84% to 105%, while the contents of REEs were significantly correlated with each other. Chondrite-normalized patterns of REEs were characterized by higher enrichment of light REEs than heavy REEs, and a depletion of Eu in the SPM was generally found. The positive anomaly of Eu in the SPM of Xi River was due to anthropogenic source in Shenyang City. Furthermore, chondfite- and upper continent crust-normalized patterns of REEs in the SPM of Daliao River system, sediments of Yangtze River and Yellow River, sediments of Yellow Sea, East Sea, South Sea of China, and loess and soil of China, were very similar to one another. These demonstrated that the weathering and sedimentary processes resulted in constant REE distribution not only in the typical sedimentary rocks, but also in the modem riverine particle, sea sediments, loess, and soils.     

Aconitum sp. alkaloids: the modulation of voltage-dependent Na+ channels, toxicity and antinociceptive properties

Alkaloids from Aconitum sp., used as analgesics in traditional Chinese medicine, were investigated to elucidate their antinociceptive and toxic properties considering: (1) binding to Na+ channel epitope site 2, (2) alterations in synaptosomal Na+ and Ca2+ concentration ([Na+]i, [Ca2+]i), (3) arrhythmogenic action of isolated atria, (4) antinociceptive and (5) acute toxic action in mice. The study revealed a high affinity group (Ki 1 microM) and a low affinity group (Ki 10 microM) of alkaloids binding to site 2. The compounds of the high affinity group induce an increase in synaptosomal [Na+]i and [Ca2+]i (EC50 3 microM), are antinociceptive (ED50, 25 microg/kg), provoke tachyarrhythmia and are highly toxic (LD50 70 microg/kg), whereas low affinity alkaloids reduce [Ca2+]i, induce bradycardia and are less antinociceptive (ED50 20 mg/kg) and less toxic (LD50 30 mg/kg). These results suggest that the alkaloids can be grouped in Na+ channel activating and blocking compounds, but none of the alkaloids seem to be suitable as analgesics because of the low LD50/ED50 values.     

Coal and coal byproducts:A large and developable unconventional resource for critical materials—Rare earth elements

Rare earth elements(REEs) are critical materials and provide significant values to national security,energy production, environmental protection and economic growth. The supply of REEs in U.S. solely relies on import as domestic production of REEs was ceased because of the environmental concerns during mining and lack of competitiveness. Nonetheless, unconventional REEs-containing resources,including produced water. acid mine drainage, and coal and coal byproducts(CCBs) contain significant amounts of REEs. However, the concentrations of REEs in these resources are several orders of magnitude lower than that of REEs ores. Thus, extraction of REEs from these materials is challenging. Here we report REEs extraction with environmentally friendly method that successfully concentrated REEs from312 ppm in fly ash to 99.4% in the final product. Especially, the five critically important REEs(Dy, Eu, Nd.Tb. and Y) account for up to ～63% of the total weight of all REEs in the final 99.4%-purity product. Coal fly ash is one of the major solid coal utilization byproducts, representing great potential resources for REEs extraction. Extraction of REEs from these unconventional resources could be the way to secure domestic supply of these critical materials.     

韧性剪切变形条件下花岗岩中稀土元素变化特征研究

本文对郯庐断裂带南段安徽境内管店花岗岩及其韧性剪切带中的糜棱化岩石进行了主要元素和稀土元素的研究。在详细的野外工作基础上,由岩体向韧性剪切带中心系统测量地质剖面并采集有代表性的岩石样品进行室内分析研究。分析结果显示,随着岩石受剪切变形作用的加强,稀土元素呈富集的趋势。各岩石球粒陨石标准化图解表现为右倾型,即轻稀土富集型。轻稀土也是随着岩石变形作用的加强而较重稀土元素富集。全文详细探讨了韧性剪切变形作用条件下岩石中稀土元素的活化转移的原因,我们认为变质－变形－流体渗滤的联合作用是导致岩石中稀土元素活化转移的主要因素。     

Efficient extraction and stripping of Nd(III), Eu(III) and Er(III) by membrane dispersion micro-extractors

The extraction of low concentration rare earth elements at high phase ratio was investigated. The traditional extraction set-up, such as mixer-settler, have drawbacks of easy emulsification, difficult separation and low efficiency if operated at the above condition. Membrane dispersion micro-extractor, owing to its well-dispersed, high surface-to-volume ratio and fast mass transfer rate, was employed in our work. Nd(III), Eu(III), Er(III) were chosen to represent light, medium, heavy rare earth elements (REEs). The extraction process of REEs with 2-ethylhexyl phosphoric acid-2-ethylhexyl ester (P507) was investigated by membrane dispersion micro-extractors. Firstly, the extraction equilibrium of these three elements was explored in the stirred conical flasks, and it is indicated that the extraction efficiencies can be 0.95, 0.97 and 0.98, respectively within 40 min at phase ratio of 100:1. Then the effects of operational conditions such as the residence time, organic and aqueous flow rates on extraction efficiency were also explored in micro-extractors. The results indicate that the efficiency decreases and then increases if increasing aqueous phase flow rate, residence time and droplets' diameter are the key factors of this process. Increasing the phase ratio reduces the extraction efficiency significantly. When the REEs solution has an initial pH of 4.00, the flow rates of continuous and dispersed phase are 40 and 1.6 mL/min, respectively, and 90 mg/L Nd (III), Eu(III) and Er(III) is extracted by 1 mol/L P507 at the out-let length of 8 m. The extraction efficiencies are 0.978, 0.983 and 0.991, respectively. Finally the stripping process was also studied with the micro-extractor. The stripping efficiencies of Nd(III), Eu(III) and Er(III) can reach 0.99, 0.96 and 0.91, respectively when the out-let length is 8 m and the concentration of hydrochloric acid is 1 mol/L. The developed approach offers a novel and simple strategy on the fast extraction and enrichment of low concentration rare earth elements from waste water.