In this paper,core samples from the Well LS33 in the deep-water area of the Qiongdongnan Basin(QDNB)in the South China Sea were selected and analyzed by group(authigenic carbonate and terrigenous detritus)to obtain th...In this paper,core samples from the Well LS33 in the deep-water area of the Qiongdongnan Basin(QDNB)in the South China Sea were selected and analyzed by group(authigenic carbonate and terrigenous detritus)to obtain the contents of rare earth elements(REE)to explore the degree of preservation of paleo-seawater information by carbonate components and elucidate the provenance relationship between the QDNB and the Yinggehai Basin and the provenance changes in the deep-water area of the QDNB since the Oligocene.The main achievements of this paper are as follows:(1)In the process of extracting the autogenic carbonate,the iron-manganese oxide envelope on the surface of the sediment particles(which can adsorb REE or its complexes in seawater)will partially dissolve into the autogenic carbonate components,thus covering the REE geochem-ical information of paleo-seawater carried by the auto-genic carbonate.Therefore,caution should be exercised when using the geochemical characteristics of REE in the carbonate component of impure carbonate rocks to reflect the sedimentary paleoenvironment.(2)The analysis of the REE geochemical characteristics of multiple cores in the Ying-gehai-QDNB shows that there is a close provenance rela-tionship between the two Basins.The sediments in the central depression area of the Yinggehai Basin and the deep-water area in the western part of the QDNB generally contain more feldspar(Eu-rich)minerals.Since the Eocene,paleo-rivers have carried ultramafic-mafic materials originating from the western South China Sea into the sea.Affected by the transport distance and sea level changes,the content of feldspar(Eu-rich)minerals in the sediments of the QDNB from west to east gradually decreased.展开更多
Rare earth elements(REEs)play a crucial role in many technologies from daily appliances in cell phones to more advanced wind turbines and electric cars.Permanent magnets account for a quarter of total global REEs prod...Rare earth elements(REEs)play a crucial role in many technologies from daily appliances in cell phones to more advanced wind turbines and electric cars.Permanent magnets account for a quarter of total global REEs production and have high recycling value.In this study,smelting process was used to selectively oxidize REEs in the permanent magnets by adding Fe_(2)O_(3).This separates REEs into a slag phase from an iron-rich metallic phase.B_(2)O_(3) was also added to the system as a flux to lower the slag melting temperature.This minimizes REEs loss to the metallic phase and allows a more efficient phase separation.The effect of flux and oxidizing agent addition was investigated on both regular and cerium-rich NdFeB(NdCeFeB)magnets.At 1350℃and for 1 h,the slag phase was successfully separated from the metallic phase with the addition of 0.8 stoichiometric amount of Fe_(2)O_(3) and 40 wt%of B_(2)O_(3).Scanning electron microscopy-energy dispersive X-ray spectroscopy(SEM-EDX)analysis reveals that REEs in the magnet do not migrate to the metal phase while the REE-rich slag phase contains almost no iron.After the selective removal of iron into the metallic phase,REEs are recovered from the slag phase through an acid leaching process allowing>99%of REEs recovery.Boron in the magnet can also be recovered as useful boric acid by evaporation and crystallisation technique.The proposed process in this study is reagent and energy-efficient with almost complete valorisation of both NdCeFeB and NdFeB magnets.展开更多
With the growing awareness of environmental protection and the increasing demand for rare earth elements(REEs),it has become necessary to efficiently remove and recover REEs from mine wastewater.In this study,jarosite...With the growing awareness of environmental protection and the increasing demand for rare earth elements(REEs),it has become necessary to efficiently remove and recover REEs from mine wastewater.In this study,jarosite(Jar)and schwertmannite(Sch)were biosynthesized using Acidithiobacillus ferrooxidans for the adsorption of REEs.Additionally,the adsorption capacities of Jar and Sch for La^(3+),Ce^(3+),Pr^(3+),Nd^(3+),Sm^(3+),Gd^(3+),Dy^(3+),and Y^(3+)in mine wastewater were improved by mechanical activation.XRD,FTIR,BET,and SEM-EDS analyses revealed that mechanical activation did not alter the phase of the material,but increased the amount of surface-OH and SO42−groups,as well as the specific surface area.This significantly enhanced the adsorption performance of Jar and Sch for REEs.The optimum adsorption time and pH were determined through batch adsorption experiments.Besides,the adsorption kinetics were studied and found to align well with the pseudo-second-order model.Furthermore,the thermodynamic parameters(ΔG^(Θ),ΔH^(Θ)andΔS^(Θ))and adsorption isotherms were analyzed.The results indicated that mechanically activated schwertmannite(M-Sch)exhibited superior adsorption performance for REEs compared to mechanically activated jarosite(M-Jar).Moreover,M-Sch was reusable and exhibited high adsorption efficiency of REEs in actual mine wastewater,exceeding 92%.展开更多
This study investigates the distribution,geochemical behavior,and potential anthropogenic influences of rare earth elements(REEs)in the surface sediments of Qinghai Lake,the largest saline lake in China.A total of 36 ...This study investigates the distribution,geochemical behavior,and potential anthropogenic influences of rare earth elements(REEs)in the surface sediments of Qinghai Lake,the largest saline lake in China.A total of 36 surface sediment samples were analyzed for REE concentrations with a combination of self-organizing maps(SOM)and positive matrix factorization(PMF).Results indicate distinct enrichment patterns,with light REEs(LREEs)exhibiting higher concentrations than heavy REEs(HREEs),reflecting natural abundances and geochemical behaviors.The minimum value was found in Lu as low as 0.091 mg/kg,and the maximum concentration was exhibited in Ce at 78.877 mg/kg.Geoaccumulation index(I_(geo))analysis reveals minor to moderate enrichment of specific REEs of Sm and Nd,suggesting possible localized anthropogenic inputs,particularly near river mouths.Spatial analysis using inverse distance weighting(IDW)and self-organizing maps(SOM)highlights significant correlations between REE distributions and riverine inputs,underscoring fluvial transport's role in sedimentary REE dynamics.PMF identifies mixed natural and anthropogenic sources,with agricultural and industrial activities contributing to elevated REE levels in sediment.These findings provide critical insights into the geochemical behavior of REEs in saline lake systems and off er a foundation for pollution control and sustainable resource management in sensitive environments like Qinghai Lake.展开更多
The demand for neodymium(NdFeB) permanent magnets for electric vehicles and eco-friendly generators is increasing.However,NdFeB magnets contain rare earth elements(REEs),which are limited in supply.In this study,we pe...The demand for neodymium(NdFeB) permanent magnets for electric vehicles and eco-friendly generators is increasing.However,NdFeB magnets contain rare earth elements(REEs),which are limited in supply.In this study,we performed an exchange reaction between magnesium halides(fluoride and chloride) and waste NdFeB scrap and then compared the characteristics of the extracted halides salts.The compositions of the ternary Mg fluoride(LiF:NaF:MgF_(2)=50:40:10 in mole ratio) and chloride(LiCl:NaCl:MgCl_(2)=10:50:40 in mole ratio) salts were thermodynamically determined for achieving low eutectic temperatures.The reactions between the NdFeB scrap powder(1-2 mm) and Mg halide salts were carried out at 1073 and 873 K for the fluoride and chloride systems,respectively,in an argon atmosphere.After the reaction,we separated Nd halide from the residual salt and evaluated the Ndextraction rate.The phase formation of the salt was analyzed using X-ray diffraction(XRD),and the extraction rate of Nd was analyzed using inductively coupled plasma optical emission spectroscopy(ICPOES).Nd was extracted in the form of Nd halide(NdF_(3) or NdCl_(3)),and the extraction rates in the fluoride and chloride systems are 98.64% and 84.59%,respectively.Thus,the fluoride system is more effective than the chloride system for Nd extraction.Our study provides a comprehensive comparative analysis of the effectiveness of fluo ride and chlo ride systems in extracting REEs from NdFeB magnet scrap.Our study findings can be used to develop an effective method for recycling magnet scraps.展开更多
Co-associated rare earth elements(lanthanide and yttrium,REY)in coal and its by-products have been considered important potential nontraditional rare earth sources.In this study,a coal gangue sample collected from a c...Co-associated rare earth elements(lanthanide and yttrium,REY)in coal and its by-products have been considered important potential nontraditional rare earth sources.In this study,a coal gangue sample collected from a coal processing plant in Jinsha County of Guizhou Province,southwest China,was used as the research object.The content,modes of occurrence,and extraction(acid leaching after pretreatment of selective grinding,tailings discarding,and alkali roasting)of REY from the sample were analyzed.The result shows that the content of REY(1038.26μg/g)in pyrite and quartz is low but mainly enriched in kaolinite.Under the following conditions of a filling ratio of 40%(grinding media steel ball)and grinding time of 8 min,selective grinding pretreatment is applied to achieve 176.95μg/g(yield 24.08%)and 1104.93μg/g(yield 75.92%)of REY in+2 mm and-2 mm fractions,respectively.Thus,the-2 mm coal gangue fraction is selected,used as the feed,and roasted and leached with HCl.When Na_(2)CO_(3)and NaCl are separately used as roasting activators,the REY leaching ratios are 91.41%and 68.88%,respectively,under the optimum conditions.The contents of REY in the final leachate are 1010.02 and 761.08μg/g when Na_(2)CO_(3)and NaCl are used,respectively.The two REY contents are relatively higher than the impurity ions in the leachate,which facilitates further REY separation.The mechanism study reveals that high-temperature roasting increases the pore size and the total pore area of the gangue,which promotes leachate penetration and improves reaction efficiency.In addition,roasting facilitates the reaction between the sodium salt activator and kaolinite and other aluminosilicate minerals in the coal gangue to generate soluble salts,thus releasing REY into the solution.The appropriate roasting temperature transforms the activator into a molten state.Thus,the reaction between coal gangue and activator is a solid-liquid reaction rather than a solid-solid reaction,which improves the efficiency of the chemical reaction.展开更多
The increasing demand for electronics has led to a desire to recover rare earth elements(REEs) from nonconventional sources,including mining and liquid waste effluents.Biosorption could be a promising method for adsor...The increasing demand for electronics has led to a desire to recover rare earth elements(REEs) from nonconventional sources,including mining and liquid waste effluents.Biosorption could be a promising method for adsorbing REEs onto microalgae,but biomass immobilization and light delivery challenges remain.It was recently shown that REEs biosorb 160% more on algal biofilms than suspended biomass due to the extracellular polymeric substance(EPS) matrix that grows abundantly in biofilms.In this work,we present findings on biosorption selectivity for different REEs in sulfate solutions.The maximum adsorption capacities of Euglena mutabilis suspensions and biofilms were determined for a mixed REE sulfate solution at an equimolar initial concentration range of 0.1-1 mol/L of each REE ion.The highest adsorption capacities for the suspension are for Sm and Eu which are 57% and 46% higher,respectively,compared to the average REE adsorption capacity.The biofilms also preferentially adsorb Sm,Eu,Yb and Lu at 0.035,0.033,0.033,and 0.031 mmol/g,respectively.The impact of dissolved divalent ions of Ca,Mg,and Fe on REE adsorption was also assessed.When Ca and Mg are added in equimolar amounts to0.1-1 mmol/L solutions of equimolar La,Eu,and Yb sulfate,the amount of REEs adsorbed onto suspensions increases by 30% while when Fe is added,it decreases by 10%.No change is observed in biofilms except when Fe is added resulting in a reduction of the adsorption capacity by 40%.A possible explanation for the role of Fe is attributed to the formation of stronger bonds at the binding sites compared to Ca and Mg.展开更多
The presence of inorganic constituents in coal is controlled by different geological factors,which,in turn,affect the technological,environmental,and health impacts of the coal.The main aim of this study is to objecti...The presence of inorganic constituents in coal is controlled by different geological factors,which,in turn,affect the technological,environmental,and health impacts of the coal.The main aim of this study is to objectively assess the mineralogical and geochemical characteristics of a thickest low-rank coal seam in the Lower Indus Basin southeastern Pakistan,and further investigate different controlling factors.The analytical results of major oxides,trace elements,and rare earth elements revealed that the weathering conditions were progressively variable and moderate.The sediment source,mainly of felsic and intermediate composition,was dominated by granitic rocks.The geochemical assessment reveals different depositional factors like marine environment influenced,while transitional and freshwater sediments influenced the center of the coal peat mire.Strontium,Zinc,and several hazardous trace elements,including Cu,Ni,Cr,and Co,have higher concentrations in these coals compared to world low-rank,U.S.,and Chinese coals.The relatively higher concentration of Sr in the thick coal seam in the Lower Indus Basin,compared to other coals seams in Pakistan and the enrichment of Sr was primarily controlled by the denudation of crystalline rocks and marine influx in the coal-basin.The REY distribution pattern showed that enrichment of medium and heavy rare earth elements is higher than light rare earth elements in the coal seam.The Gd distribution pattern in the coal seam demonstrated that strong positive anomalies had a good affinity with paleo-acidic water concentration in the study area.The higher concentration of Sr and other elements enables a better assessment understanding of the coal geochemical history.展开更多
This study details a comprehensive approach focusing on the effective separation of light rare earth elements(REEs)via solvent extraction technique.A stock solution containing lanthanum,cerium,neodymium,praseodymium,a...This study details a comprehensive approach focusing on the effective separation of light rare earth elements(REEs)via solvent extraction technique.A stock solution containing lanthanum,cerium,neodymium,praseodymium,and samarium was prepared by dissolving their pure mixed oxide(reclaimed from spent Ni-MH batteries)in a diluted HCl solution.Key extractants,including bis(2,4,4-trimethylpentyl)phosphinic acid(Cyanex 272),Cyanex 572,trialkylphosphine oxide(Cyanex 923),and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester(PC 88A),along with tributyl phosphate(TBP)as a phase modifier,were utilized to form organic systems.The extraction behavior and separability of these systems at various pH levels as well as their extraction mechanisms were investigated.The results demonstrated a direct relationship between the extraction trend and the experimental pH value,with enhanced selectivity when TBP was added.Notably,Nd and Pr exhibited similar extraction behaviors,with minor deviations from Ce,making their separation difficult to achieve.Sm extraction followed a distinct trend,allowing for its separation from other elements at pH≤2.In contrast,La exhibited a low affinity for coordination with extractants when pH was≤3.5,facilitating the separation of other elements from La,which could then be isolated in the raffinate.Among the studied organic systems,combinations of Cyanex 572 and PC 88A with TBP demonstrated superior performance in element separation.Optimum separation factors were calculated withβ_(Ce/La)=12,βNd/La=87,β_(Pr/La)=127,andβ_(Sm/La)=3191 for the former,andβ_(Sm/Ce)=54,β_(Sm/Nd)=20,andβ_(Sm/Pr)=14 for the latter.These findings provide valuable insights for selecting extraction systems and designing experiments for the effective solvent extraction separation of light REEs from their mixture.展开更多
Rare earth elements(REEs) are associated with phosphorite,which is an important strategic reserve resource.During sorting process of phosphorite,REEs may move with specific host minerals,however,occurrence state and m...Rare earth elements(REEs) are associated with phosphorite,which is an important strategic reserve resource.During sorting process of phosphorite,REEs may move with specific host minerals,however,occurrence state and moving pattern of REEs from rock to products are still unclear,which limits separation and enrichment of REEs from phosphorite.Mappings of scanning electron microscope(SEM) and electron probe X-ray micro-analyzer(EPMA) of REEs are highly consistent with those of calcium and phosphorus,and complementary with that of magnesium,which indicates that fluorapatite(Fap) is the main host mineral of REEs.The results of flotation and leaching experiments further indicate that REEs are enriched along with Fap from phosphorite to products.Occupied sites and occupation number of REEs were obtained by X-ray diffraction(XRD) refinement based on the Rietveld method.La,Ce,Nd,and Y can occupy both Ca1 and Ca2 sites.The ratios of La,Ce,Nd,and Y at Ca2 and Cal sites are 4.20,3.70,3.00,and 1.33,showing a decreasing trend,indicating that La,Ce,and Nd tend to occupy Ca2 sites,while Y tends to occupy Ca1 sites.X-ray absorption fine structure(XAFS) shows that REEs mainly form coordinate structures with oxygen and fluorine,which is a direct evidence that REEs replace calcium(Ⅱ) in phosphorite in an isomorphism form.Coordination structure and polyhedral configuration analysis indicate that substitution degree of La,Ce,Nd,and Y is Y> La> Ce≈Nd from easy to difficult at Cal and Ca2 sites.The research enriches the mineralization theory of REEs-bearing phosphorite and provides certain theoretical guidance for selective enrichment of REEs from phosphorite.展开更多
Ion-absorption deposits(IADs)of rare earth elements(REEs)constitute the main economic resources of the essential heavy rare earth elements(HREE).Nonetheless,the existing leaching methods for extracting REEs from IADs ...Ion-absorption deposits(IADs)of rare earth elements(REEs)constitute the main economic resources of the essential heavy rare earth elements(HREE).Nonetheless,the existing leaching methods for extracting REEs from IADs face limitations stemming from significant environmental consequences and a poor REE recovery rate.In a recent development,electrokinetic mining(EKM)has emerged as a novel technology for extracting REEs from ion-adsorption deposits,demonstrating the potential for environmentally friendly and efficient recovery of REEs from weathering crusts.However,the transport mechanism of REE in weathering crust soil in an applied electric field remains poorly understood,and the influence of the EKM process has yet to be studied.In this study,we systematically investigated the transport characteristics of REE in weathering crust soil under the influence of an electric field.We demonstrate that the transport of REE is simultaneous with the transport of water,H+,and OH-in the applied electric field,where the EKM process is influenced by the voltage gradient,initial soil water content,electrode numbers,and power-on time.Under the optimal EKM conditions,78,8%of REE is recovered from a 45 kg-scale weathering crust soil.Additionally,we identify the transport diversity between light REE(LREE)and HREE,which assists in the separation and pre-enrichment of LREE and HREE.Furthermore,we demonstrate that the mechanism for REE transport under an electric field involves a combination of electromigration,electroosmosis,and electrolysis working synergistically.This study provides new perspectives on the transport behavior and mechanism of REEs in weathering crust soil under an electric field.These findings pave the way for the practical implementation of EKM technology.展开更多
Toxic effects in terms of mitochondria and hereditary substances have been characterized in vitro for individual rare earth elements,while,the joint effects of mixed elements exposure in the population remain ambiguou...Toxic effects in terms of mitochondria and hereditary substances have been characterized in vitro for individual rare earth elements,while,the joint effects of mixed elements exposure in the population remain ambiguous.Based on the Occupational Chromate Exposure Dynamic Cohort of China,this study investigated the relationship between 15 blood rare earth elements(cerium,dysprosium,erbium,europium,gadolinium,holmium,lanthanum,lutetium,neodymium,praseodymium,samarium,terbium,thulium,yttrium,and ytterbium)and mitochondrial DNA copy number(MtDNACN)as well as peripheral blood lymphocyte micronucleus frequency(MNF).The elastic net was used to select elements highly correlated with effect indicators,whose dose-response relationships were further illustrated by restricted cubic splines.Bayesian kernel regressionwas employed to explore the combined effects of elements and the contributions of single element.The results showed that most rare earth elementswere positively correlatedwith effect indicators,with yttrium showing the strongest association(β(95%CI):0.139(0.1089–0.189)for MtDNACN,0.937(0.345–1.684)for MNF).In the mixed exposure model,with the exposure level fixed at the 50th percentile as the reference,the effect estimates on MtDNACN and MNF increased by 0.228 and 0.598 units,respectively,at the 75th percentile.The single effect analysis implied that yttrium,lanthanum and terbium contributed the most to the elevation of MtDNACN,while yttrium posed the highest risk for genetic damage,accordingly,we provided recommendations to prioritize these elements of concern.In addition,we observed a chief mediating effect of MtDNACN on the elevation of MNF caused by lanthanum,whereas further mechanistic exploration is required to confirm this finding.展开更多
Rare-earth elements(REEs)received special attention and widespread application because of their extremely active chemical property.Many researches demonstrated that doping of REEs(Y,La and Ce)in superalloys can signif...Rare-earth elements(REEs)received special attention and widespread application because of their extremely active chemical property.Many researches demonstrated that doping of REEs(Y,La and Ce)in superalloys can significantly improve the high temperature oxidation resistance,corrosion resistance and mechanical properties,which are recognized as a promising route to broaden the manufacturing process window and enhance the overall performance of next-generation superalloys.The first part of this review described the special behavior of REEs during the metallurgical solidification process,including the REEs loss in the melt and the macro-segregation phenomenon.The second part summarized a broad spectrum of works reporting the dual role of REEs addition on the mechanical properties of superalloys.The third part overviewed the effect of REEs on the anti-oxidation resistance of the fourth and fifth nickel-based superalloys.Finally,the prospect of development of REEs-containing superalloys was discussed.展开更多
Co/NC catalysts modified with rare earth elements(La,Ce,Pr)were prepared by pyrolysis of rare earth elements doped ZIF-67.The experimental results show that the modification of rare earth elements significantly improv...Co/NC catalysts modified with rare earth elements(La,Ce,Pr)were prepared by pyrolysis of rare earth elements doped ZIF-67.The experimental results show that the modification of rare earth elements significantly improves the ammonia decomposition activity and stability of the Co/NC catalyst.The La-Co/NC catalyst can achieve an 82.3%ammonia decomposition and 18.4 mmol hydrogen production rate at 550℃with a GHSV of 20000 cm^(3)·h^(-1).Furthermore,no obvious performance degradation is observed after 72 hours of reaction for all rare earth elements modified catalysts.It is shown that the modification of rare earth elements significantly improves the surface alkalinity and surface chemical state of the catalyst,and thus improves the ammonia decomposition activity of the catalyst.A new type of high-performance ammonia decomposition Co-based catalyst is proposed,and the promoting effect of rare earth elements on the activity of ammonia decomposition is revealed.展开更多
Objective The study aimed to investigate the impact of rare earth elements(REEs)exposure on pregnancy outcomes of in vitro fertilization-embryo transfer(IVF-ET)by analyzing samples from spouses.Methods A total of 141 ...Objective The study aimed to investigate the impact of rare earth elements(REEs)exposure on pregnancy outcomes of in vitro fertilization-embryo transfer(IVF-ET)by analyzing samples from spouses.Methods A total of 141 couples were included.Blood and follicular fluid from the wives and semen plasma from the husbands,were analyzed for REEs using inductively coupled plasma mass spectrometry(ICP-MS).Spearman's correlation coefficients and the Mann–Whitney U test were used to assess correlations and compare REE concentrations among three types of samples,respectively.Logistic models were utilized to estimate the individual REE effect on IVF-ET outcomes,while BKMR and WQS models explored the mixture of REE interaction effects on IVF-ET outcomes.Results Higher La concentration in semen(median 0.089 ng/mL,P=0.03)was associated with a lower fertilization rate.However,this effect was not observed after artificial selection intervention through intracytoplasmic sperm injection(ICSI)(P=0.27).In semen,the REEs mixture did not exhibit any significant association with clinical pregnancy.Conclusion Our study revealed a potential association between high La exposure in semen and a decline in fertilization rate,but not clinical pregnancy rate.This is the first to report REEs concentrations in follicular fluid with La,Ce,Pr,and Nd found at significantly lower concentrations than in serum,suggesting that these four REEs may not accumulate in the female reproductive system.However,at the current exposure levels,mixed REEs exposure did not exhibit reproductive toxicity.展开更多
In this decade,coal fly ash(CFA)is considered a potential secondary source of rare earth elements(REEs).However,most REEs in coal fly ash are encapsulated in aluminosilicate glass,making it challenging to recover them...In this decade,coal fly ash(CFA)is considered a potential secondary source of rare earth elements(REEs).However,most REEs in coal fly ash are encapsulated in aluminosilicate glass,making it challenging to recover them through acid leaching.In this study,a sequential alkaline-organic acid leaching was developed for the recovery of REEs from CFA.The effect of alkaline leaching using NaOH solution on the destructive ability of aluminosilicate glass,as well as the mineralogy and morphology changes of the resulting coal fly ash,was first studied.Furthermore,the effectiveness of alkaline leaching on the recovery ability of REEs through organic acid leaching was evaluated.The results show that the maximum leaching efficiency for Si and Al,which was obtained at the optimum alkaline leaching conditions,namely NaOH concentration of 10 mol/L,reaction temperature of 65℃,liquid/solid(L/S)ratio of 10 mL/g,and reaction time of 90 min,is 28%and 32%,respectively.The digestion reaction with NaOH lixiviants also causes coal fly ash to become more porous,making it advantageous in the organic acid-leaching process at the REEs recovery stage.The utilization of the desilicated residue produced from the digestion process in acid leaching effectively increases the overall REEs recovery from 32.2%to 77.6%.展开更多
Conventional mining of economically and strategically important critical rare earth elements(REEs)(such as neodymium,lanthanum and dysprosium),and chalcogens(such as selenium and tellurium)are associated with a huge e...Conventional mining of economically and strategically important critical rare earth elements(REEs)(such as neodymium,lanthanum and dysprosium),and chalcogens(such as selenium and tellurium)are associated with a huge economic and environmental cost.Therefore,the need to recover REEs as well as chalcogens from different waste streams including wastewaters is becoming urgent.Batch assays on synthetic chalcogen/REE-laden wastewater showed that the presence of REEs significantly improved the tellurite removal rate(>80%)and enhanced selenate removal by 66%±10%.Three 3.9 L continuous upflow anaerobic granular sludge bed(UASB)reactors were operated at a hydraulic retention time of 24 h and 30℃.Selenate reduction was achieved with a removal efficiency of~98% with an influent p H of 4.0 for more than 28 days.The effect of REEs on tellurite removal in the UASB bioreactor could not be clearly established since a soluble tellurium removal efficiency of more than 98%was observed already before the addition of REEs at elevated tellurite concentrations.The complete REE removal in both batch assays and UASB reactors at higher pH(7.0±0.5)was attributed to precipitation,whereas chalcogen oxyanions removal was due to microbial reduction.However,at acidic p H,biosorption was responsible for REE's removal,and the Se-enriched sludge exhibited a superior REE's removal efficiency than the non-enriched and Te-enriched sludge.展开更多
The booming development of rare earth industry and the extensive utilization of its products accompanied by urban development have led to the accelerated accumulation of rare earth elements(REEs)as emerging pollutants...The booming development of rare earth industry and the extensive utilization of its products accompanied by urban development have led to the accelerated accumulation of rare earth elements(REEs)as emerging pollutants in atmospheric environment.In this study,the variation of REEs in PM_(2.5)with urban(a non-mining city)transformation was investigated through five consecutive years of sample collection.The compositional variability and provenance contribution of REEs in PM_(2.5)were characterized,and the REEs exposure risks of children and adults via inhalation,ingestion and dermal absorption were also evaluated.The results showed an increase in the total REEs concentration from 46.46±35.16 mg/kg(2017)to 81.22±38.98 mg/kg(2021)over the five-year period,with Ce and La making the largest contribution.The actual increment of industrial and traffic emission source among the three pollution sources was 1.34 ng/m^(3).Coal combustion source displayed a downward trend.Ingestion was the main exposure pathway for REEs in PM_(2.5)for both children and adults.Ce contributed the most to the total intake of REEs in PM_(2.5)among the population,followed by La and Nd.The exposure risks of REEs in PM_(2.5)in the region were relatively low,but the trend of change was of great concern.It was strongly recommended to strengthen the concern about traffic-related non-exhaust emissions of particulate matter.展开更多
The small muddy areas developed in the southern Shandong Peninsula have attracted increasing attention from researchers because of complex changes in sediment sources driven by sea-level fluctuations and land-sea inte...The small muddy areas developed in the southern Shandong Peninsula have attracted increasing attention from researchers because of complex changes in sediment sources driven by sea-level fluctuations and land-sea interactions since the late Pleistocene.This study investigates the evolution of sediment sources and their responses to environmental changes since the late Pleistocene,using core WHZK01 collected from the nearshore muddy area in southern Weihai for rare earth element(REE)analysis.In doing so,this work highlights the changing patterns of material sources and the primary control factors.The results reveal that the sedimentary deposits in core WHZK01 exhibit distinct terrestrial characteristics.Discriminant function analysis(F_(D))and source discrimination dia-grams both suggest that the primary sources of these deposits are the Yellow River and adjacent small and medium-sized rivers,although the sources vary among different sedimentary units.Furthermore,the DU3 layer(17.82-25.10 m)displays typical riverine sedimentation,dominated by terrestrial detrital input,primarily from the local rivers,namely the Huanglei and Muzhu Rivers.The material in the DU2 layer(14.91-17.82 m)is mainly influenced by a mixture of the Qinglong and Yellow Rivers.The DU1 layer(0-14.91 m)is influenced by sea-level changes during the Holocene,with the Yellow River being the primary source,although there is also some input from local rivers.The changes in sea level during the Holocene and the input of Yellow River material carried by the coastal currents of the Yellow Sea are identified as the main controlling factors for the changes in material sources in the study area since the late Pleistocene,with small and mediumsized rivers also exerting some influence on the material sources.The above mentioned findings not only contribute to a better understanding of the source-sink systems of the Yellow River and adjacent small and mediumsized rivers but also deepen our understanding of the late Quaternary land-sea interactions in the Shandong Peninsula.展开更多
The luminescent phosphor powder in the fluorescent lamp constitutes 2%of the lamp’s weight.It can be mentioned that fluorescent wastes are a crucial raw material to produce rare earth oxides.In the present study,micr...The luminescent phosphor powder in the fluorescent lamp constitutes 2%of the lamp’s weight.It can be mentioned that fluorescent wastes are a crucial raw material to produce rare earth oxides.In the present study,microwave leaching process was conducted to dissolve rare earth elements yttrium(Y),europium(Eu),and remaining rare earth elements(REEs)present in the phosphor powder of the fluorescent lamp.and the yields were compared.In the microwave leaching process,the effects of the temperature(80-160℃),acid type(hydrochloric acid(HCl),nitric acid(HNO_(3)),sulphuric acid(H_(2)SO_(4))),acid concentration(0.5-6 mol/L),solid to liquid ratio(0.1:10-0.5:10)and reaction time(5-90 min)parameters on leaching efficiencies of varying rare earth elements and calcium were investigated.The highest yield was obtained in the direct microwave leaching of fluorescent waste with the experimental conditions of 6 mol/L HCl,160℃,0.1:10 solid-to-liquid ratio(S:L),and 90 min.Activation energy calculations were made,and kinetic models of the reactions were obtained,and it is observed that Y and Eu dissolution is diffusion-controlled,on the other hand,lanthanum(La),cerium(Ce),and terbium(Tb)were examined to be chemical reaction controlled.Moreover,calcium(Ca)and gadolinium(Gd)seem coherent with the mixed model.Concurrently,mathematical models of all experimental studies are created with the response surface Box-Behnken method and the correlation coefficients of all the models are over 90%.展开更多
基金supported by The National Science and Technology Major Project under contract(No.2011ZX05025-002-03)The Project of China National Offshore Oil Corporation(CNOOC)Limited under contract(No.CCL2013ZJFNO729)The National Natural Science Foundation of China under contract(No.41530963)。
文摘In this paper,core samples from the Well LS33 in the deep-water area of the Qiongdongnan Basin(QDNB)in the South China Sea were selected and analyzed by group(authigenic carbonate and terrigenous detritus)to obtain the contents of rare earth elements(REE)to explore the degree of preservation of paleo-seawater information by carbonate components and elucidate the provenance relationship between the QDNB and the Yinggehai Basin and the provenance changes in the deep-water area of the QDNB since the Oligocene.The main achievements of this paper are as follows:(1)In the process of extracting the autogenic carbonate,the iron-manganese oxide envelope on the surface of the sediment particles(which can adsorb REE or its complexes in seawater)will partially dissolve into the autogenic carbonate components,thus covering the REE geochem-ical information of paleo-seawater carried by the auto-genic carbonate.Therefore,caution should be exercised when using the geochemical characteristics of REE in the carbonate component of impure carbonate rocks to reflect the sedimentary paleoenvironment.(2)The analysis of the REE geochemical characteristics of multiple cores in the Ying-gehai-QDNB shows that there is a close provenance rela-tionship between the two Basins.The sediments in the central depression area of the Yinggehai Basin and the deep-water area in the western part of the QDNB generally contain more feldspar(Eu-rich)minerals.Since the Eocene,paleo-rivers have carried ultramafic-mafic materials originating from the western South China Sea into the sea.Affected by the transport distance and sea level changes,the content of feldspar(Eu-rich)minerals in the sediments of the QDNB from west to east gradually decreased.
基金Project supported by the Science and Engineering Research Board of India(SRG/2020/002096)。
文摘Rare earth elements(REEs)play a crucial role in many technologies from daily appliances in cell phones to more advanced wind turbines and electric cars.Permanent magnets account for a quarter of total global REEs production and have high recycling value.In this study,smelting process was used to selectively oxidize REEs in the permanent magnets by adding Fe_(2)O_(3).This separates REEs into a slag phase from an iron-rich metallic phase.B_(2)O_(3) was also added to the system as a flux to lower the slag melting temperature.This minimizes REEs loss to the metallic phase and allows a more efficient phase separation.The effect of flux and oxidizing agent addition was investigated on both regular and cerium-rich NdFeB(NdCeFeB)magnets.At 1350℃and for 1 h,the slag phase was successfully separated from the metallic phase with the addition of 0.8 stoichiometric amount of Fe_(2)O_(3) and 40 wt%of B_(2)O_(3).Scanning electron microscopy-energy dispersive X-ray spectroscopy(SEM-EDX)analysis reveals that REEs in the magnet do not migrate to the metal phase while the REE-rich slag phase contains almost no iron.After the selective removal of iron into the metallic phase,REEs are recovered from the slag phase through an acid leaching process allowing>99%of REEs recovery.Boron in the magnet can also be recovered as useful boric acid by evaporation and crystallisation technique.The proposed process in this study is reagent and energy-efficient with almost complete valorisation of both NdCeFeB and NdFeB magnets.
基金Project(2022YFC2105300) supported by the National Key Research and Development Program of ChinaProject(52274288) supported by the National Natural Science Foundation of China。
文摘With the growing awareness of environmental protection and the increasing demand for rare earth elements(REEs),it has become necessary to efficiently remove and recover REEs from mine wastewater.In this study,jarosite(Jar)and schwertmannite(Sch)were biosynthesized using Acidithiobacillus ferrooxidans for the adsorption of REEs.Additionally,the adsorption capacities of Jar and Sch for La^(3+),Ce^(3+),Pr^(3+),Nd^(3+),Sm^(3+),Gd^(3+),Dy^(3+),and Y^(3+)in mine wastewater were improved by mechanical activation.XRD,FTIR,BET,and SEM-EDS analyses revealed that mechanical activation did not alter the phase of the material,but increased the amount of surface-OH and SO42−groups,as well as the specific surface area.This significantly enhanced the adsorption performance of Jar and Sch for REEs.The optimum adsorption time and pH were determined through batch adsorption experiments.Besides,the adsorption kinetics were studied and found to align well with the pseudo-second-order model.Furthermore,the thermodynamic parameters(ΔG^(Θ),ΔH^(Θ)andΔS^(Θ))and adsorption isotherms were analyzed.The results indicated that mechanically activated schwertmannite(M-Sch)exhibited superior adsorption performance for REEs compared to mechanically activated jarosite(M-Jar).Moreover,M-Sch was reusable and exhibited high adsorption efficiency of REEs in actual mine wastewater,exceeding 92%.
基金funded by the Basic Research Program of Qinghai Province(2023-ZJ-910M)。
文摘This study investigates the distribution,geochemical behavior,and potential anthropogenic influences of rare earth elements(REEs)in the surface sediments of Qinghai Lake,the largest saline lake in China.A total of 36 surface sediment samples were analyzed for REE concentrations with a combination of self-organizing maps(SOM)and positive matrix factorization(PMF).Results indicate distinct enrichment patterns,with light REEs(LREEs)exhibiting higher concentrations than heavy REEs(HREEs),reflecting natural abundances and geochemical behaviors.The minimum value was found in Lu as low as 0.091 mg/kg,and the maximum concentration was exhibited in Ce at 78.877 mg/kg.Geoaccumulation index(I_(geo))analysis reveals minor to moderate enrichment of specific REEs of Sm and Nd,suggesting possible localized anthropogenic inputs,particularly near river mouths.Spatial analysis using inverse distance weighting(IDW)and self-organizing maps(SOM)highlights significant correlations between REE distributions and riverine inputs,underscoring fluvial transport's role in sedimentary REE dynamics.PMF identifies mixed natural and anthropogenic sources,with agricultural and industrial activities contributing to elevated REE levels in sediment.These findings provide critical insights into the geochemical behavior of REEs in saline lake systems and off er a foundation for pollution control and sustainable resource management in sensitive environments like Qinghai Lake.
基金supported by the Technology Innovation (20010817,Technology for the ecofriendly rare earth refining from used motors and manufacture of permanent magnet materials) funded by the Ministry of Trade,Industry & Energy (MOTIE),Korea。
文摘The demand for neodymium(NdFeB) permanent magnets for electric vehicles and eco-friendly generators is increasing.However,NdFeB magnets contain rare earth elements(REEs),which are limited in supply.In this study,we performed an exchange reaction between magnesium halides(fluoride and chloride) and waste NdFeB scrap and then compared the characteristics of the extracted halides salts.The compositions of the ternary Mg fluoride(LiF:NaF:MgF_(2)=50:40:10 in mole ratio) and chloride(LiCl:NaCl:MgCl_(2)=10:50:40 in mole ratio) salts were thermodynamically determined for achieving low eutectic temperatures.The reactions between the NdFeB scrap powder(1-2 mm) and Mg halide salts were carried out at 1073 and 873 K for the fluoride and chloride systems,respectively,in an argon atmosphere.After the reaction,we separated Nd halide from the residual salt and evaluated the Ndextraction rate.The phase formation of the salt was analyzed using X-ray diffraction(XRD),and the extraction rate of Nd was analyzed using inductively coupled plasma optical emission spectroscopy(ICPOES).Nd was extracted in the form of Nd halide(NdF_(3) or NdCl_(3)),and the extraction rates in the fluoride and chloride systems are 98.64% and 84.59%,respectively.Thus,the fluoride system is more effective than the chloride system for Nd extraction.Our study provides a comprehensive comparative analysis of the effectiveness of fluo ride and chlo ride systems in extracting REEs from NdFeB magnet scrap.Our study findings can be used to develop an effective method for recycling magnet scraps.
基金Project supported by the National Natural Science Foundation of China(51964009)。
文摘Co-associated rare earth elements(lanthanide and yttrium,REY)in coal and its by-products have been considered important potential nontraditional rare earth sources.In this study,a coal gangue sample collected from a coal processing plant in Jinsha County of Guizhou Province,southwest China,was used as the research object.The content,modes of occurrence,and extraction(acid leaching after pretreatment of selective grinding,tailings discarding,and alkali roasting)of REY from the sample were analyzed.The result shows that the content of REY(1038.26μg/g)in pyrite and quartz is low but mainly enriched in kaolinite.Under the following conditions of a filling ratio of 40%(grinding media steel ball)and grinding time of 8 min,selective grinding pretreatment is applied to achieve 176.95μg/g(yield 24.08%)and 1104.93μg/g(yield 75.92%)of REY in+2 mm and-2 mm fractions,respectively.Thus,the-2 mm coal gangue fraction is selected,used as the feed,and roasted and leached with HCl.When Na_(2)CO_(3)and NaCl are separately used as roasting activators,the REY leaching ratios are 91.41%and 68.88%,respectively,under the optimum conditions.The contents of REY in the final leachate are 1010.02 and 761.08μg/g when Na_(2)CO_(3)and NaCl are used,respectively.The two REY contents are relatively higher than the impurity ions in the leachate,which facilitates further REY separation.The mechanism study reveals that high-temperature roasting increases the pore size and the total pore area of the gangue,which promotes leachate penetration and improves reaction efficiency.In addition,roasting facilitates the reaction between the sodium salt activator and kaolinite and other aluminosilicate minerals in the coal gangue to generate soluble salts,thus releasing REY into the solution.The appropriate roasting temperature transforms the activator into a molten state.Thus,the reaction between coal gangue and activator is a solid-liquid reaction rather than a solid-solid reaction,which improves the efficiency of the chemical reaction.
基金supported by Natural Sciences and Engineering Research Council of Canada Strategic Grants program(463037-14)Discovery Grants program(2016-05524,2022-04881,2020-04262)。
文摘The increasing demand for electronics has led to a desire to recover rare earth elements(REEs) from nonconventional sources,including mining and liquid waste effluents.Biosorption could be a promising method for adsorbing REEs onto microalgae,but biomass immobilization and light delivery challenges remain.It was recently shown that REEs biosorb 160% more on algal biofilms than suspended biomass due to the extracellular polymeric substance(EPS) matrix that grows abundantly in biofilms.In this work,we present findings on biosorption selectivity for different REEs in sulfate solutions.The maximum adsorption capacities of Euglena mutabilis suspensions and biofilms were determined for a mixed REE sulfate solution at an equimolar initial concentration range of 0.1-1 mol/L of each REE ion.The highest adsorption capacities for the suspension are for Sm and Eu which are 57% and 46% higher,respectively,compared to the average REE adsorption capacity.The biofilms also preferentially adsorb Sm,Eu,Yb and Lu at 0.035,0.033,0.033,and 0.031 mmol/g,respectively.The impact of dissolved divalent ions of Ca,Mg,and Fe on REE adsorption was also assessed.When Ca and Mg are added in equimolar amounts to0.1-1 mmol/L solutions of equimolar La,Eu,and Yb sulfate,the amount of REEs adsorbed onto suspensions increases by 30% while when Fe is added,it decreases by 10%.No change is observed in biofilms except when Fe is added resulting in a reduction of the adsorption capacity by 40%.A possible explanation for the role of Fe is attributed to the formation of stronger bonds at the binding sites compared to Ca and Mg.
基金supported by the National Natural Science Foundation of China,funding numbers 41690131,41572327,51874280 and 5264015.
文摘The presence of inorganic constituents in coal is controlled by different geological factors,which,in turn,affect the technological,environmental,and health impacts of the coal.The main aim of this study is to objectively assess the mineralogical and geochemical characteristics of a thickest low-rank coal seam in the Lower Indus Basin southeastern Pakistan,and further investigate different controlling factors.The analytical results of major oxides,trace elements,and rare earth elements revealed that the weathering conditions were progressively variable and moderate.The sediment source,mainly of felsic and intermediate composition,was dominated by granitic rocks.The geochemical assessment reveals different depositional factors like marine environment influenced,while transitional and freshwater sediments influenced the center of the coal peat mire.Strontium,Zinc,and several hazardous trace elements,including Cu,Ni,Cr,and Co,have higher concentrations in these coals compared to world low-rank,U.S.,and Chinese coals.The relatively higher concentration of Sr in the thick coal seam in the Lower Indus Basin,compared to other coals seams in Pakistan and the enrichment of Sr was primarily controlled by the denudation of crystalline rocks and marine influx in the coal-basin.The REY distribution pattern showed that enrichment of medium and heavy rare earth elements is higher than light rare earth elements in the coal seam.The Gd distribution pattern in the coal seam demonstrated that strong positive anomalies had a good affinity with paleo-acidic water concentration in the study area.The higher concentration of Sr and other elements enables a better assessment understanding of the coal geochemical history.
基金support from the Australian Research Council’s Industrial Transformation Research Hub funding scheme(project IH190100009).
文摘This study details a comprehensive approach focusing on the effective separation of light rare earth elements(REEs)via solvent extraction technique.A stock solution containing lanthanum,cerium,neodymium,praseodymium,and samarium was prepared by dissolving their pure mixed oxide(reclaimed from spent Ni-MH batteries)in a diluted HCl solution.Key extractants,including bis(2,4,4-trimethylpentyl)phosphinic acid(Cyanex 272),Cyanex 572,trialkylphosphine oxide(Cyanex 923),and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester(PC 88A),along with tributyl phosphate(TBP)as a phase modifier,were utilized to form organic systems.The extraction behavior and separability of these systems at various pH levels as well as their extraction mechanisms were investigated.The results demonstrated a direct relationship between the extraction trend and the experimental pH value,with enhanced selectivity when TBP was added.Notably,Nd and Pr exhibited similar extraction behaviors,with minor deviations from Ce,making their separation difficult to achieve.Sm extraction followed a distinct trend,allowing for its separation from other elements at pH≤2.In contrast,La exhibited a low affinity for coordination with extractants when pH was≤3.5,facilitating the separation of other elements from La,which could then be isolated in the raffinate.Among the studied organic systems,combinations of Cyanex 572 and PC 88A with TBP demonstrated superior performance in element separation.Optimum separation factors were calculated withβ_(Ce/La)=12,βNd/La=87,β_(Pr/La)=127,andβ_(Sm/La)=3191 for the former,andβ_(Sm/Ce)=54,β_(Sm/Nd)=20,andβ_(Sm/Pr)=14 for the latter.These findings provide valuable insights for selecting extraction systems and designing experiments for the effective solvent extraction separation of light REEs from their mixture.
基金Project supported by Guizhou Provincial Basic Research Program (Natural Science)(Qian Ke He Basic-ZK 2024 General 626)National Natural Science Foundation of China (52164018)Scientific Research Foundation for High-level Talents of Anhui University of Science and Technology (13210025)。
文摘Rare earth elements(REEs) are associated with phosphorite,which is an important strategic reserve resource.During sorting process of phosphorite,REEs may move with specific host minerals,however,occurrence state and moving pattern of REEs from rock to products are still unclear,which limits separation and enrichment of REEs from phosphorite.Mappings of scanning electron microscope(SEM) and electron probe X-ray micro-analyzer(EPMA) of REEs are highly consistent with those of calcium and phosphorus,and complementary with that of magnesium,which indicates that fluorapatite(Fap) is the main host mineral of REEs.The results of flotation and leaching experiments further indicate that REEs are enriched along with Fap from phosphorite to products.Occupied sites and occupation number of REEs were obtained by X-ray diffraction(XRD) refinement based on the Rietveld method.La,Ce,Nd,and Y can occupy both Ca1 and Ca2 sites.The ratios of La,Ce,Nd,and Y at Ca2 and Cal sites are 4.20,3.70,3.00,and 1.33,showing a decreasing trend,indicating that La,Ce,and Nd tend to occupy Ca2 sites,while Y tends to occupy Ca1 sites.X-ray absorption fine structure(XAFS) shows that REEs mainly form coordinate structures with oxygen and fluorine,which is a direct evidence that REEs replace calcium(Ⅱ) in phosphorite in an isomorphism form.Coordination structure and polyhedral configuration analysis indicate that substitution degree of La,Ce,Nd,and Y is Y> La> Ce≈Nd from easy to difficult at Cal and Ca2 sites.The research enriches the mineralization theory of REEs-bearing phosphorite and provides certain theoretical guidance for selective enrichment of REEs from phosphorite.
基金Projects supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA0430205)Guangdong Major Project of Basic and Applied Basic Research(2019B030302013)+2 种基金National Natural Science Foundation of China(42102037,42272158)Guangdong Basic and Applied Basic Research Foundation(2023A1515012927)Science and Technology Planning of Guangdong Province,China(2023B1212060048)。
文摘Ion-absorption deposits(IADs)of rare earth elements(REEs)constitute the main economic resources of the essential heavy rare earth elements(HREE).Nonetheless,the existing leaching methods for extracting REEs from IADs face limitations stemming from significant environmental consequences and a poor REE recovery rate.In a recent development,electrokinetic mining(EKM)has emerged as a novel technology for extracting REEs from ion-adsorption deposits,demonstrating the potential for environmentally friendly and efficient recovery of REEs from weathering crusts.However,the transport mechanism of REE in weathering crust soil in an applied electric field remains poorly understood,and the influence of the EKM process has yet to be studied.In this study,we systematically investigated the transport characteristics of REE in weathering crust soil under the influence of an electric field.We demonstrate that the transport of REE is simultaneous with the transport of water,H+,and OH-in the applied electric field,where the EKM process is influenced by the voltage gradient,initial soil water content,electrode numbers,and power-on time.Under the optimal EKM conditions,78,8%of REE is recovered from a 45 kg-scale weathering crust soil.Additionally,we identify the transport diversity between light REE(LREE)and HREE,which assists in the separation and pre-enrichment of LREE and HREE.Furthermore,we demonstrate that the mechanism for REE transport under an electric field involves a combination of electromigration,electroosmosis,and electrolysis working synergistically.This study provides new perspectives on the transport behavior and mechanism of REEs in weathering crust soil under an electric field.These findings pave the way for the practical implementation of EKM technology.
基金supported by the National Natural Science Foundation of China(Nos.U200420282273603 and 82003427).
文摘Toxic effects in terms of mitochondria and hereditary substances have been characterized in vitro for individual rare earth elements,while,the joint effects of mixed elements exposure in the population remain ambiguous.Based on the Occupational Chromate Exposure Dynamic Cohort of China,this study investigated the relationship between 15 blood rare earth elements(cerium,dysprosium,erbium,europium,gadolinium,holmium,lanthanum,lutetium,neodymium,praseodymium,samarium,terbium,thulium,yttrium,and ytterbium)and mitochondrial DNA copy number(MtDNACN)as well as peripheral blood lymphocyte micronucleus frequency(MNF).The elastic net was used to select elements highly correlated with effect indicators,whose dose-response relationships were further illustrated by restricted cubic splines.Bayesian kernel regressionwas employed to explore the combined effects of elements and the contributions of single element.The results showed that most rare earth elementswere positively correlatedwith effect indicators,with yttrium showing the strongest association(β(95%CI):0.139(0.1089–0.189)for MtDNACN,0.937(0.345–1.684)for MNF).In the mixed exposure model,with the exposure level fixed at the 50th percentile as the reference,the effect estimates on MtDNACN and MNF increased by 0.228 and 0.598 units,respectively,at the 75th percentile.The single effect analysis implied that yttrium,lanthanum and terbium contributed the most to the elevation of MtDNACN,while yttrium posed the highest risk for genetic damage,accordingly,we provided recommendations to prioritize these elements of concern.In addition,we observed a chief mediating effect of MtDNACN on the elevation of MNF caused by lanthanum,whereas further mechanistic exploration is required to confirm this finding.
基金supported by the National Science and Technology Major Project(Nos.J2019-VI-0023-0139 and J2019-VII-0004-0144)the National Key R&D Program of China(No.2020YFA0714904).
文摘Rare-earth elements(REEs)received special attention and widespread application because of their extremely active chemical property.Many researches demonstrated that doping of REEs(Y,La and Ce)in superalloys can significantly improve the high temperature oxidation resistance,corrosion resistance and mechanical properties,which are recognized as a promising route to broaden the manufacturing process window and enhance the overall performance of next-generation superalloys.The first part of this review described the special behavior of REEs during the metallurgical solidification process,including the REEs loss in the melt and the macro-segregation phenomenon.The second part summarized a broad spectrum of works reporting the dual role of REEs addition on the mechanical properties of superalloys.The third part overviewed the effect of REEs on the anti-oxidation resistance of the fourth and fifth nickel-based superalloys.Finally,the prospect of development of REEs-containing superalloys was discussed.
基金Funded in part by the Natural Science Foundation of China(No.22279096)the Guangdong Basic and Applied Basic Research Foundation(No.2021B1515120072)。
文摘Co/NC catalysts modified with rare earth elements(La,Ce,Pr)were prepared by pyrolysis of rare earth elements doped ZIF-67.The experimental results show that the modification of rare earth elements significantly improves the ammonia decomposition activity and stability of the Co/NC catalyst.The La-Co/NC catalyst can achieve an 82.3%ammonia decomposition and 18.4 mmol hydrogen production rate at 550℃with a GHSV of 20000 cm^(3)·h^(-1).Furthermore,no obvious performance degradation is observed after 72 hours of reaction for all rare earth elements modified catalysts.It is shown that the modification of rare earth elements significantly improves the surface alkalinity and surface chemical state of the catalyst,and thus improves the ammonia decomposition activity of the catalyst.A new type of high-performance ammonia decomposition Co-based catalyst is proposed,and the promoting effect of rare earth elements on the activity of ammonia decomposition is revealed.
基金supported by the National Key Research and Development Program of China(2022YFC2702900 and 2021YFC2701103)National Natural Science Foundation of China(82171654)。
文摘Objective The study aimed to investigate the impact of rare earth elements(REEs)exposure on pregnancy outcomes of in vitro fertilization-embryo transfer(IVF-ET)by analyzing samples from spouses.Methods A total of 141 couples were included.Blood and follicular fluid from the wives and semen plasma from the husbands,were analyzed for REEs using inductively coupled plasma mass spectrometry(ICP-MS).Spearman's correlation coefficients and the Mann–Whitney U test were used to assess correlations and compare REE concentrations among three types of samples,respectively.Logistic models were utilized to estimate the individual REE effect on IVF-ET outcomes,while BKMR and WQS models explored the mixture of REE interaction effects on IVF-ET outcomes.Results Higher La concentration in semen(median 0.089 ng/mL,P=0.03)was associated with a lower fertilization rate.However,this effect was not observed after artificial selection intervention through intracytoplasmic sperm injection(ICSI)(P=0.27).In semen,the REEs mixture did not exhibit any significant association with clinical pregnancy.Conclusion Our study revealed a potential association between high La exposure in semen and a decline in fertilization rate,but not clinical pregnancy rate.This is the first to report REEs concentrations in follicular fluid with La,Ce,Pr,and Nd found at significantly lower concentrations than in serum,suggesting that these four REEs may not accumulate in the female reproductive system.However,at the current exposure levels,mixed REEs exposure did not exhibit reproductive toxicity.
基金Project supported by the Ministry of Research,Technology and Higher Education,Republic of Indonesia(0386/E4/BP/2021)Universitas Gadjah Mada(1501407/UN1.FTK/SK/HK/2022)。
文摘In this decade,coal fly ash(CFA)is considered a potential secondary source of rare earth elements(REEs).However,most REEs in coal fly ash are encapsulated in aluminosilicate glass,making it challenging to recover them through acid leaching.In this study,a sequential alkaline-organic acid leaching was developed for the recovery of REEs from CFA.The effect of alkaline leaching using NaOH solution on the destructive ability of aluminosilicate glass,as well as the mineralogy and morphology changes of the resulting coal fly ash,was first studied.Furthermore,the effectiveness of alkaline leaching on the recovery ability of REEs through organic acid leaching was evaluated.The results show that the maximum leaching efficiency for Si and Al,which was obtained at the optimum alkaline leaching conditions,namely NaOH concentration of 10 mol/L,reaction temperature of 65℃,liquid/solid(L/S)ratio of 10 mL/g,and reaction time of 90 min,is 28%and 32%,respectively.The digestion reaction with NaOH lixiviants also causes coal fly ash to become more porous,making it advantageous in the organic acid-leaching process at the REEs recovery stage.The utilization of the desilicated residue produced from the digestion process in acid leaching effectively increases the overall REEs recovery from 32.2%to 77.6%.
基金financially by the Erasmus+programme of the European Union,the Science Foundation Ireland(SFI)through the SFI Research Professorship Programme entitled Innovative Energy Technologies for Biofuels,Bioenergy and a Sustainable Irish Bioeconomy(IETSBIO3)(No.15/RP/2763)the Research Infrastructure Research Grant Platform for Biofuel Analysis(No.16/RI/3401).
文摘Conventional mining of economically and strategically important critical rare earth elements(REEs)(such as neodymium,lanthanum and dysprosium),and chalcogens(such as selenium and tellurium)are associated with a huge economic and environmental cost.Therefore,the need to recover REEs as well as chalcogens from different waste streams including wastewaters is becoming urgent.Batch assays on synthetic chalcogen/REE-laden wastewater showed that the presence of REEs significantly improved the tellurite removal rate(>80%)and enhanced selenate removal by 66%±10%.Three 3.9 L continuous upflow anaerobic granular sludge bed(UASB)reactors were operated at a hydraulic retention time of 24 h and 30℃.Selenate reduction was achieved with a removal efficiency of~98% with an influent p H of 4.0 for more than 28 days.The effect of REEs on tellurite removal in the UASB bioreactor could not be clearly established since a soluble tellurium removal efficiency of more than 98%was observed already before the addition of REEs at elevated tellurite concentrations.The complete REE removal in both batch assays and UASB reactors at higher pH(7.0±0.5)was attributed to precipitation,whereas chalcogen oxyanions removal was due to microbial reduction.However,at acidic p H,biosorption was responsible for REE's removal,and the Se-enriched sludge exhibited a superior REE's removal efficiency than the non-enriched and Te-enriched sludge.
基金supported by the National Natural Science Foundation of China(No.22176056)the Fundamental Research Funds for the Central Universities(No.2017ZZD07)。
文摘The booming development of rare earth industry and the extensive utilization of its products accompanied by urban development have led to the accelerated accumulation of rare earth elements(REEs)as emerging pollutants in atmospheric environment.In this study,the variation of REEs in PM_(2.5)with urban(a non-mining city)transformation was investigated through five consecutive years of sample collection.The compositional variability and provenance contribution of REEs in PM_(2.5)were characterized,and the REEs exposure risks of children and adults via inhalation,ingestion and dermal absorption were also evaluated.The results showed an increase in the total REEs concentration from 46.46±35.16 mg/kg(2017)to 81.22±38.98 mg/kg(2021)over the five-year period,with Ce and La making the largest contribution.The actual increment of industrial and traffic emission source among the three pollution sources was 1.34 ng/m^(3).Coal combustion source displayed a downward trend.Ingestion was the main exposure pathway for REEs in PM_(2.5)for both children and adults.Ce contributed the most to the total intake of REEs in PM_(2.5)among the population,followed by La and Nd.The exposure risks of REEs in PM_(2.5)in the region were relatively low,but the trend of change was of great concern.It was strongly recommended to strengthen the concern about traffic-related non-exhaust emissions of particulate matter.
基金supported by the Natural Science Foundation of Shandong Province(No.ZR2022MD114)the Project of Global Earth Observation on Asian Delta and Estuary Corresponding to Anthropogenic Impacts and Climate Changes(No.2019YFE0127200).
文摘The small muddy areas developed in the southern Shandong Peninsula have attracted increasing attention from researchers because of complex changes in sediment sources driven by sea-level fluctuations and land-sea interactions since the late Pleistocene.This study investigates the evolution of sediment sources and their responses to environmental changes since the late Pleistocene,using core WHZK01 collected from the nearshore muddy area in southern Weihai for rare earth element(REE)analysis.In doing so,this work highlights the changing patterns of material sources and the primary control factors.The results reveal that the sedimentary deposits in core WHZK01 exhibit distinct terrestrial characteristics.Discriminant function analysis(F_(D))and source discrimination dia-grams both suggest that the primary sources of these deposits are the Yellow River and adjacent small and medium-sized rivers,although the sources vary among different sedimentary units.Furthermore,the DU3 layer(17.82-25.10 m)displays typical riverine sedimentation,dominated by terrestrial detrital input,primarily from the local rivers,namely the Huanglei and Muzhu Rivers.The material in the DU2 layer(14.91-17.82 m)is mainly influenced by a mixture of the Qinglong and Yellow Rivers.The DU1 layer(0-14.91 m)is influenced by sea-level changes during the Holocene,with the Yellow River being the primary source,although there is also some input from local rivers.The changes in sea level during the Holocene and the input of Yellow River material carried by the coastal currents of the Yellow Sea are identified as the main controlling factors for the changes in material sources in the study area since the late Pleistocene,with small and mediumsized rivers also exerting some influence on the material sources.The above mentioned findings not only contribute to a better understanding of the source-sink systems of the Yellow River and adjacent small and mediumsized rivers but also deepen our understanding of the late Quaternary land-sea interactions in the Shandong Peninsula.
基金BAP project FBA-2021-4691 for their financial support。
文摘The luminescent phosphor powder in the fluorescent lamp constitutes 2%of the lamp’s weight.It can be mentioned that fluorescent wastes are a crucial raw material to produce rare earth oxides.In the present study,microwave leaching process was conducted to dissolve rare earth elements yttrium(Y),europium(Eu),and remaining rare earth elements(REEs)present in the phosphor powder of the fluorescent lamp.and the yields were compared.In the microwave leaching process,the effects of the temperature(80-160℃),acid type(hydrochloric acid(HCl),nitric acid(HNO_(3)),sulphuric acid(H_(2)SO_(4))),acid concentration(0.5-6 mol/L),solid to liquid ratio(0.1:10-0.5:10)and reaction time(5-90 min)parameters on leaching efficiencies of varying rare earth elements and calcium were investigated.The highest yield was obtained in the direct microwave leaching of fluorescent waste with the experimental conditions of 6 mol/L HCl,160℃,0.1:10 solid-to-liquid ratio(S:L),and 90 min.Activation energy calculations were made,and kinetic models of the reactions were obtained,and it is observed that Y and Eu dissolution is diffusion-controlled,on the other hand,lanthanum(La),cerium(Ce),and terbium(Tb)were examined to be chemical reaction controlled.Moreover,calcium(Ca)and gadolinium(Gd)seem coherent with the mixed model.Concurrently,mathematical models of all experimental studies are created with the response surface Box-Behnken method and the correlation coefficients of all the models are over 90%.
