Element distribution in electrochemically treated mine wastewater for efficient resource recovery and water treatment: A pilot study

The feasibility of recovering major and critical elements from acid mine drainage using a pilot-scale electrochemical reactor (ECR) was investigated by assessing elements concentration and species distribution in the liquid and solid phase (sludge) in multistage tests. These were carried out at different electrical currents (18-22 amps) and thus, pH (8-12). The results showed that major metals Al, Cu and Fe were removed from the liquid phase at pH 5.9 while remaining the majority of Zn (57.2 ppm). On the other hand, at pH 7, the effluent was mainly composed of Mn (7.3 ppm). These results were confirmed by the simulation results using the PHREEQC model, which also identified the main chemical species in solution and the precipitates formed after the treatment (oxyhydroxides/sulfates/oxides). The ECR treatment led to sludges with targeted critical elements, some up to 20 times (Co, Be and Sb) higher than their earth's crustal abundance. At pH 10, rare earth elements in the sludge targeted Ce, followed by Nd and La. This study is one of the few studies carrying a detailed analysis of the behavioural distribution pattern of these elements at each pH, which opens the door for the potential of recovering these elements.

Improved recovery selectivity of rare earth elements from mining wastewater utilizing phytosynthesized iron nanoparticles

While rare earth elements (REEs) play key roles in many modern technologies, the selectivity of recovering of REEs from mining wastewater remains a critical problem. In this study, iron nanoparticles (FeNPs) synthesized from euphorbia cochinchinensis extracts were successfully used for selective recovery of REEs from real mining wastewater with removal efficiencies of 89.4% for Y(III), 79.8% for Ce(III) and only 6.15% for Zn(Ⅱ). FTIR and XPS analysis suggested that the high selective removal efficiency of Y(III) and Ce(III) relative to Zn(Ⅱ) on FeNPs was due to a combination of selective REEs adsorption via complexing with O or N, ion exchange with H+ present in functional groups contained within the capping layer and electrostatic interactions. Adsorptions of Y(III) and Ce(III) on FeNPs conformed to pseudo second-order kinetics and the Langmuir isotherm model with maximum adsorption capacities of 5.10 and 0.695 mg∙g-1, respectively. The desorption efficiencies of Y(III) and Ce(III) were, respectively, 95.0 and 97.9% in 0.05 M acetic acid, where desorption involved competitive ion exchange between Y(III), Ce(III) and Zn(Ⅱ) with H+ contained in acetic acid and intraparticle diffusion. After four consecutive adsorption-desorption cycles, adsorption efficiencies for Y(III) and Ce(III) remained relatively high at 52.7% and 50.1%, respectively, while desorption efficiencies of Y(III) and Ce(III) were > 80.0% and 95.0%, respectively. Overall, excellent reusability suggests that FeNPs can practically serve as a potential high-quality selectivity material for recovering REEs from mining wastewaters.

Synthesis, Solid State Structure, and Cytotoxic Activity of a Complex Dimer of Yttrium with Anthranilic Acid against Cancer Cells

This paper presents the synthesis and isolation of a new binuclear complex of yttrium with anthranilic acid (HA). The complex [Y2(HA)6(H2O)4] Cl6.2C2H5OH (C1) was obtained as single crystals that its X-ray analysis revealed its triclinic P-1 space group in addition to anti-prismatic geometry around each of the yttrium ions. In the complex, the anthranilic acid ligands are bidentate, zwitter ionic and neutral, and the yttrium ions' charge is only compensated by six chloride ions. The cytotoxicity of this complex against human breast cancer MDA-MB-231 cells, prostate cancer PC-3 cells, and bladder cancer T-24 cells was evaluated. This yttrium complex displayed more cytotoxic activity against the bladder cancer cells with an IC50 value of 307.7 μg/ml (223 μM). On the other hand, the activities of complex C1 against the MDA-MB-231 and PC-3 cells were less significant respectively with IC50 values of 1097 μg/ml (796 μM) and 921 μg/ml (669 μM).

Geochemical characteristics of the Rajmahal coals in Dhulia North Block, Eastern India: implication to their utilization and environment

The borehole coal samples of Dhulia North Block from the Rajmahal Basin, Eastern India, were systematically analyzed based on the chemical composition and concentration of major and trace elements (including rare earth elements, REEs) to assess the distribution of REEs and their environmental implications with utilization potential. The Dhulia North Block coals are characterized by the predominant major oxides of SiO2, Al2O3, and Fe2O3, accounting for 94% of the total ash composition, indicating the presence of quartz, clay-rich minerals, and pyrite. Compared with the average world coal ash, the total REE content in the analyzed samples ranged from 341.0 to 810.4 ppm, which is substantially higher. Hot humid climate conditions with intermediate igneous source rocks of the basin were demonstrated by the major oxide ratios (Al2O3/TiO2 < 20) and plots of TiO2 with Al2O3 and Zr. The redox-sensitive elements such as V, Ni, Cr, and Co found in the Dhulia North Block coal indicate that an oxic sedimentary environment existed in the basin when coal was formed. The low sulfur content (1% in most samples) indicates freshwater conditions in the basin at the time of organic matter deposition. The outlook coefficient (Coutl) varies between 0.7 and 1.6, indicating that the Dhulia North Block coals are a prospective source of REEs. The Dhulia North Block coals are characterized by low H/C and O/C atomic ratios ranging from 0.56 to 0.90 and 0.10 to 0.22, respectively, and contain type-III kerogens, indicating gas-prone source rock. Further, the basic-to-acid oxide ratio suggested that Dhulia North Block coals were suitable for utilization during combustion processes.

Mechanisms of water-rock interaction and implications for remediating flooded mine workings elucidated from environmental tracers, stable isotopes, and rare earth elements

Contamination from acid mine drainage affects ecosystems and usability of groundwater for domestic and municipal purposes. The Captain Jack Superfund Site outside of Ward, Boulder County, Colorado, USA, hosts a draining mine adit that was remediated through emplacement of a hydraulic bulkhead to preclude acid mine drainage from entering nearby Lefthand Creek. During impoundment of water within the mine workings in 2020, a diverse and novel dataset of stable isotopes of water, sulfate, and carbon (δ 2 H , δ 18 O H 2 O , δ 18 O SO 4 , δ 34 S , δ 13 C DIC ), rare earth elements, and environmental tracers (noble gases and tritium) were collected to understand groundwater recharge and mixing, mechanisms of sulfide oxidation and water-rock interaction, and the influence of remediation on the hydrologic and geochemical system. Water isotopes indicate that groundwater distal from the mine workings has seasonally variable recharge sources whereas water within the workings has a distinctive composition with minimal temporal variability. Sulfate isotopes indicate that sulfide oxidation occurs both within the mine workings and in adjacent igneous dikes, and that sulfide oxidation may occur under suboxic conditions with ferric iron as the oxidant. Carbon isotopes track the neutralization of acidic waters and the carbon mass budget of the system. Rare earth elements corroborate stable isotopes in indicating groundwater compartmentalization, and additionally illustrate enhanced mineral weathering in the mine workings. Environmental tracers indicate mixing of modern and pre-modern groundwater and inform timelines that active remediation may be needed. Together these datasets provide a useful template for similar investigations of abandoned mine sites where physical mixing processes, sources of solute loading, or remediation timeframes are of importance.

A critical review of the occurrence of scandium and yttrium in mushrooms

Scandium (Sc) and Yttrium (Y) along with the other rare earth elements (REE) are being increasingly extracted to meet the escalating demand for their use in modern high technology applications. Concern has been voiced that releases from this escalating usage may pollute environments, including the habitats of wild species of mushrooms, many of which are foraged and prized as foods. This review collates the scarce information on occurrence of these elements in wild mushrooms and also reviews soil substrate levels, including forested habitats. Sc and Y occurred at lower levels in mushrooms (<1.0-1000 µg kg-1 dw for Sc and<1.8-1500 µg kg-1 dw for Y) compared to the corresponding range for the sum of the lanthanides in the same species (16-8400 µg kg-1 dw). The reported species showed considerably more variation in Y contents than Sc which show a narrow median distribution range (20-40 µg kg-1 dw). Data allowing temporal examination was very limited but showed no increasing trend between the 1970s to 2019, nor were any geographical influences apparent. The study of the essentiality, toxicity or other effects of REE including Sc and Y at levels of current dietary intake are as yet undefined. High intake scenarios using the highest median concentrations of Sc and Y, resulted in daily intakes of 1.2 and 3.3 μg respectively from 300 g portions of mushroom meals. These could be considered as low unless future toxicological insights make these intake levels relevant.

Co-treatment of diamond-wire-saw silicon kerf and spent automotive catalysts for simultaneous recovery of PGMs, REEs, Zr, and high-purity Si

Spent automotive catalysts (SACs) and diamond-wire-saw silicon kerf (DWSSK) are classified as hazardous wastes. Currently, the two wastes are treated separately using unrelated approaches. More than two independent approaches are required to recover platinum group metals (PGMs), Zr and rare earth elements (REEs) from SACs, and recover Si from DWSSK, which is time-consuming and laborious. In this study, a new approach was proposed to co-treat the two wastes based on the concept of using waste treats waste: using DWSSK (∼89.85 wt% Si) as a new metal collector to extract PGMs, REEs, and Zr simultaneously from SACs to obtain a Si-VM alloy (VM: valuable metal); meanwhile, using the carrier of SACs to form molten slag to eliminate the main impurity, O, from DWSSK. The largest recovery ratios of Pd, Rh, Zr, Ce, La, and Nd from SACs were 99.50 ± 0.10%, 99.14 ± 0.14 %, 96.19 ± 0.76%, 67.18 ± 4.57%, 61.24 ± 4.93% and 47.65 ± 7.27%, respectively, and the largest removal ratio of O from DWSSK was 99.96%. After smelting, the Si-VM alloy was separated into high-purity Si and VM-containing acid solutions via acid leaching. The leaching ratios of Pd, Rh, Ce, La, Nd, and Zr were 99.78%, 98.15%, 99.93%, ∼100%, 99.76% and 99.98%, respectively. The purity of Si was upgraded from 89.85 wt% (in DWSSK) to 99.98 wt% after acid leaching. The new approach proposed in this study is considered more environmentally friendly and cost-effective than the regular approaches that treat the two wastes separately.

Wet gravity separation and froth floatation techniques for rare earth elements beneficiation from monazite ore in Jordan

The demand for extracting Rare Earth Elements (REEs) from their deposits is growing significantly around the world since they are essential in many mature and growing industries. This study investigated the elemental and mineralogical composition of a Bulk sample and its potential for rare earth elements (REEs) beneficiation through Wet Gravity Separation (WGS) and Froth Floatation (FF) processes. Results obtained from WDXRF analysis showed that Si, Hf, Ti, Fe and Zr were the major elements present in the Bulk sample, with SiO2 accounting for 64.79 wt%. The TREOs concentration was around 0.90 wt%, dominated by Ce, La, and Nd, with other REEs present in smaller concentrations. XRD analysis indicated that Quartz was the major mineral present in the Bulk sample. WGS and FF were then used to beneficiate the oxides CeO2, La2O3, Nd2O3, Pr6O11, Y2O3, Gd2O3, and Sm2O3. Results showed significant concentration increases of these elements in the WGS concentrate, with high grade and good recoveries achieved for Ce, La, and Nd. Overall, the study provides insights into the potential of WGS and FF as a beneficiation technique for REEs in monazite ore.

Eco-friendly methodology for removing and recovering rare earth elements from saline industrial wastewater

In this study, response surface methodology (RSM) was applied with a Box-Behnken design to optimize the biosorption (removal and bioconcentration) of rare earth elements (REEs) (Y, La, Ce Eu, Gd, Tb) by living Ulva sp. from diluted industrial wastewaters (also containing Pt and the classic contaminants Hg, Pb, Zn, Cu, Co, and Cd). Element concentration (A: 10-190 μg/L), wastewater salinity (B: 15-35), and Ulva sp. dosage (C: 1.0-5.0 g/L) were the operating parameters chosen for optimization. Analysis of the Box-Behnken central point confirmed the reproducibility of the methodology and p-values below 0.0001 validated the developed mathematical models. The largest inter-element differences were observed at 24 h, with most REEs, Cu, Pb and Hg showing removals ≥ 50 %. The factor with the greatest impact (positive) on element removal was the initial seaweed dosage (ANOVA, p < 0.05). The optimal conditions for REEs removal were an initial REEs concentration of 10 μg/L, at a wastewater salinity of 15, and an Ulva sp. dosage of 5.0 g/L, attaining removals up to 88 % in 24 h. Extending the time to 96 h allowed seaweed dosage to be reduced to 4.2 g/L while achieving removals ≥ 90 %. The high concentrations in REE-enriched biomass (∑REEs of 3222 μg/g), which are up to 3000 times higher than those originally found in water and exceed those in common ores, support their use as an alternative source of these critical raw materials.

Multivariate analysis of trace elements in starry sturgeon (Acipenser stellatus) spine in different areas of the Caspian Sea

Sturgeons are one of the most valuable species in the Caspian Sea. There, habitation of the seabed and feeding on benthic organisms makes this species a good indicator of trace element status. Thus, we aimed to determine the concentrations of 31 trace elements in the pectoral fin spine of starry sturgeons, and to evaluate the relationships between the different chemical elements. For this, a total of 40 starry sturgeons were obtained in a repopulation programme from the coastal waters north and south of the Caspian Sea. First, we used a multivariate analysis of variance to establish the differences between zones. Later, to assess relationships between trace elements, we used principal component analysis and cluster analysis. In general, the concentration of many trace elements did not vary between zones. However, some elements, including mercury or arsenic, were found in the north areas at higher concentrations.

An assessment of the strategies for the energy-critical elements necessary for the development of sustainable energy sources

There have been several strategies developed to increase the diversified supply of energy so that it can meet all of the future demands for energy. As a result, to ensure a healthy and sustainable energy future, it is imperative to warrant reliable and diverse energy supply sources if the "green energy economy" is to be realized. The purpose of developing and deploying clean energy technologies is to improve our overall energy security, reduce our carbon footprint, and ensure that the generation of energy is secure and reliable in the future, making sure that we can spur economic growth in the future. In this paper, advancements in alternative sources of energy sustainability and strategies will be examined to ensure there will be enough fuel to supply all the future demands for energy. Several emerging clean energy technologies rely heavily on the availability of materials that exhibit unique properties that are necessary for their development. This paper examines the roles that rare earth and other energy-critical materials play in securing a clean energy economy and the development of clean energy economies in general. For the development of these technologies to be successful and sustainable, a number of these energy-critical materials are at risk of becoming unavailable. This is due to their limited availability, disruptions in supply, and a lack of suitable resources for their development. An action plan focusing on producing energy-critical materials in energy-efficient ways is discussed as part of an initiative to advance the development of clean and sustainable energy.

Characterization of lignite deposits of Barmer Basin, Rajasthan: insights from mineralogical and elemental analysis

The geochemistry of fly ash produced from the combustion of coal at thermal power plants presents a significant challenge for disposal and environmental impact due to its complex mineralogical and elemental composition. The objective of this study was to investigate the mineralogical and elemental distribution of thirty lignite samples from the Barmer Basin using advanced techniques such as X-ray diffraction (XRD), X-ray fluorescence spectrometry (XRF) and inductively coupled plasma mass spectrometry (ICP-MS). XRD analysis revealed the presence of minerals such as haematite (Fe2O3), nepheline, anhydrite, magnesite, andalusite, spinel and anatase. Other minor minerals included albite, siderite, periclase, calcite, mayenite, hauyne, pyrite, cristobalite, quartz, nosean and kaolinite. XRF analysis demonstrated that the most abundant elements in the Barmer Basin lignite ash were iron oxide (Fe2O3), sulphur oxide (SO3), calcium oxide (CaO), and quartz (SiO2) followed by minor traces of toxic oxides (SrO, V2O5, NiO, Cr2O3, Co2O3, CuO) that are known to have adverse effects on human health and the environment. The rare earth element (REE) composition showed higher concentrations of Tb, Dy, Ho, Er, Tm, Yb, Lu, Y and Sc at the Giral and lower concentrations at Sonari mine. The Barmer lignites recorded higher concentration of trace elements such as V, Cr, Co, Ni, Cu and Sr while lower concentration of Rb, Cs, Ba, Pb, As, Th and U were observed within optimal range. The study findings revealed the predominant mineral concentration, elemental makeup, trace elements and rare earth elements associated with lignite reserves in the Barmer Basin.

Bioaccumulation of rare earth elements and trace elements in different tissues of the golden grey mullet (Chelon auratus) in the southern Caspian Sea

Rare earth elements are essential for modern life, although they are also classified as emerging pollutants. Currently, fish studies on these elements are very limited in general, but, with regard to the Caspian Sea, there is no reference to them at all. For this reason, our objective was to determine the concentrations of these elements in the golden grey mullet (Chelon auratus) and to contrast its bioaccumulation patterns with those of arsenic, cadmium, mercury and lead. For that purpose, 20 fish were caught in the southern part of the Caspian Sea. Heavy rare earth element concentrations were higher than light ones and the terbium levels were very high, probably due to anthropogenic contamination. The intestine tissue gave the highest concentrations, which could be indicative of a very low gastrointestinal absorption. For both rare earth and trace elements, muscle was the tissue that accumulated the least, despite which, cadmium and lead levels in muscle were of concern.

Highly efficient removal of rare earth elements by two-dimensional titanium carbide nanosheets as impacted via water chemistry

The separation and recycling of rare earth elements (REEs) are very important owing to the high demand, limited resource, specific usages, and environmental issues. In this work, two-dimensional Ti3C2Tx MXene was introduced to remove REEs (Nd(III) and La(III)) from water, and its physicochemical properties were conducted by HRTEM, SEM-EDS, XRD, FTIR, and XPS. Various parameters, such as initial pH, REEs initial concentration, contact time, and temperature, were investigated by batch experiment, respectively. Furthermore, the adsorption kinetic and isotherm were examined to analyze the adsorption behavior and adsorption mechanism. Nd(III) and La(III) have a good affinity with Ti3C2Tx MXene surface functional groups (-F, -OH, and containing oxygen groups). The maximum adsorption capacities of Ti3C2Tx MXene for Nd(III) and La(III) were 229.85 mg/g and 175.83 mg/g at T = 333 K, respectively. The adsorption data of Nd(III) on Ti3C2Tx MXene fitted well with the Freundlich isotherms model and pseudo-second-order kinetic model. However, the best fitting for La(III) adsorption on Ti3C2Tx MXene was described by both pseudo-first-order and pseudo-second-order model. Thermodynamic study of Nd(III) and La(III) adsorption on Ti3C2Tx MXene showed that the reaction was a spontaneous and endothermic process. These results indicated Ti3C2Tx MXene had a great potential in extracting REEs from an aqueous solution.

High-temperature tribological performance of stir-cast and heat-treated EV31A magnesium alloy: Experiments and predictions

The temperature effect on the wear behaviour of EV31A Mg alloy during dry sliding wear was investigated. Wear tests were carried out at 50, 100, 150, 200, and 250 °C using a standard load of 10 N and a sliding distance of 1000 m. Weight loss method was used to calculate the wear rate. Optical microscopy was used to examine the microstructure of the EV31A alloy. FE-SEM with EDS analysis was used to investigate the wear morphology, and XRD analysis was performed both before and after the wear test. A high wear coefficient (K) value (more than 10-4) indicates extreme wear for EV31A in all the scenarios. T4 EV31A had a maximum wear rate of 20.2 mg at 150 °C. The as-cast EV31A alloy exhibits an excellent wear rate at the price of mechanical properties under all test scenarios. Wear resistance is improved by Nd and Zr oxides, although Mg and Gd oxides have little effect. Zn has no effect on the wear behaviour of the EV31A. In as-cast, T4, and T6 heat-treated conditions, the EV31A alloy exhibits delamination (abrasive wear), oxide development (corrosive wear), and delamination mixed with plastic deformation (adhesive wear). A Three-layered ANN and adapted Fine Gaussian SVM predicted tribological characteristics. In ANN prediction, the maximum R2 was 0.99 for CoF and 0.89 for wear rate, respectively. Despite the fact that the study's normal load is constant, machine learning models allow to deduce that temperature and normal load are the main influential parameters in CoF and wear rate, respectively.

Co-transport of biochar nanoparticles (BC NPs) and rare earth elements (REEs) in water-saturated porous media: New insights into REE fractionation

The present study investigated the co-transport behavior of three REEs³⁺ (La³⁺, Gd³⁺, and Yb³⁺) with and without biochar nanoparticles (BC NPs) in water-saturated porous media. The presence of REEs³⁺ enhanced the retention of BC NPs in quartz sand (QS) due to decreased electrostatic repulsion between BC NPs and QS, enhanced aggregation of BC NPs, and the contribution of straining. The distribution coefficients (K_D) in packed columns in the co-transport of BC NPs and three REEs³⁺ were much smaller than in batch experiments due to the different hydrodynamic conditions. In addition, we, for the first time, found that REE fractionation in the solid-liquid phase occurred during the co-transport of REEs³⁺ in the presence and absence of BC NPs. Note that the REE fractionation during the co-transport, which is helpful for the tracing application during earth surface processes, was driven by the interaction of REEs³⁺ with QS and BC NPs. This study elucidates novel insights into the fate of BC NPs and REEs³⁺ in porous media and indicates that (i) mutual effects between BC NPs and REE³⁺ should be considered when BC was applied to REE contaminated aquatic and soil systems; and (ii) REE fractionation provides a useful tool for identifying the sources of coexisting substances.

Probabilistic ecotoxicological risk assessment of heavy metal and rare earth element mixtures in aquatic biota using the DGT technique in coastal sediments

Heavy metals (HMs) are routine contaminants due to their extensive use worldwide. Rare earth elements (REEs) are emerging contaminants because of their global exploitation for use in the high-tech sector. Diffusive gradients in thin films (DGT) are an effective method for measuring the bioavailable component of pollutants. This study represents the first assessment of the mixture toxicity of HMs and REEs in aquatic biota using the DGT technique in sediments. Xincun Lagoon was chosen as the case study site because it has been contaminated by pollutants. Nonmetric multidimensional scaling (NMS) analysis reveals that a wide variety of pollutants (Cd, Pb, Ni, Cu, InHg, Co, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, and Yb) are primarily impacted by sediment characteristics. Appraisal of single HM-REE toxicity reveals that the risk quotient (RQ) values for Y, Yb and Ce notably exceeded 1, demonstrating that the adverse effects of these single HMs and REEs should not be ignored. The combined toxicity of HM-REE mixtures in terms of probabilistic ecological risk assessment shows that the Xincun surface sediments had a medium probability (31.29%) of toxic effects on aquatic biota.

Effect of cooking temperature on metal concentrations and speciation in fish muscle and seal liver

Fish and marine mammals constitute a significant part of the country food diet of many Indigenous communities in Canada. These animals sometimes accumulate essential elements as well as elevated levels of toxic metals. We experimentally assessed how changes in cooking temperature (23-99 °C by boiling) modified elemental concentrations in whitefish muscle and grey seal liver (two organs commonly consumed in some northern communities). Wet and dry elemental concentrations changed linearly as a function of temperature, and two patterns were observed: methylmercury, selenium, and rare earth elements tended to remain associated with the food during cooking, whereas alkali, alkaline-earth metals, and arsenic were significantly transferred to cooking juices. Mass balances indicated that speciation of mercury was stable during cooking. Because elements generally behaved similarly as those of their periodic table group or their ecotoxicological classes (A, B, intermediate), we propose that elemental behavior during cooking is partly a function of chemical affinity, and this relationship can be used to predict the behavior of data-poor elements of emerging concern, such as technology-critical elements. Furthermore, the marked increases and decreases in elemental concentrations during cooking (e.g., -14% As and +39% Se in whitefish; -22% Cd and +55% Hg in seal liver, on a wet weight basis) should be considered when assessing risk because current exposure models usually only consider elemental concentrations in raw food.

Cytotoxicity and hemolysis of rare earth ions and nanoscale/bulk oxides (La, Gd, and Yb): Interaction with lipid membranes and protein corona formation

The widespread application of rare earth elements (REEs) has raised concerns about their potential release into the environment and subsequent ingestion by humans. Therefore, it is essential to evaluate the cytotoxicity of REEs. Here, we investigated the interactions between three typical REEs (La, Gd, and Yb) ions as well as their nanometer/μm-sized oxides and red blood cells (RBCs), a plausible contact target for nanoparticles when they enter the bloodstream. Hemolysis of REEs at 50-2000 μmol L^-1 was examined to simulate their cytotoxicity under medical or occupational exposure. We found that the hemolysis due to the exposure of REEs was highly dependent on their concentration, and the cytotoxicity followed the order of La³⁺ > Gd³⁺ > Yb³⁺. The cytotoxicity of REE ions (REIs) is higher than REE oxides (REOs), while nanometer-sized REO caused more hemolysis than that μm-sized REO. The production of reactive oxygen species (ROS), ROS quenching experiment, as well as the detection of lipid peroxidation, confirmed that REEs causes cell membrane rupture by ROS-related chemical oxidation. In addition, we found that the formation of a protein corona on REEs increased the steric repulsion between REEs and cell membranes, hence mitigating the cytotoxicity of REEs. The theoretical simulation indicated the favorable interaction of REEs with phospholipids and proteins. Therefore, our findings provide a mechanistic explanation for the cytotoxicity of REEs to RBCs once they have entered the blood circulation system of organisms.

High-efficiency recovery of cerium ions from monazite leach liquor by polyamines and polycarboxylates chitosan sorbents prepared from marine industrial wastes

Rare earth elements have received a lot of attention in recent years due to their increasing demand in high-tech industries. Cerium is of current interest and is commonly used in different industries and medical applications. Cerium's uses are expanding due to its superior chemical characteristics over other metals. In this study, different functionalized chitosan macromolecule sorbents were developed from shrimp waste for cerium recovery from a leached monazite liquor. The process involves demineralization, deproteinization, deacetylation, and chemical modification steps. A new class of two-multi-dentate nitrogen and nitrogen‑oxygen donor ligand-based macromolecule biosorbents was synthesized and characterized for cerium biosorption. The crosslinked chitosan/epichlorohydrin, chitosan/polyamines, and chitosan/polycarboxylate biosorbents have been produced from marine industrial waste (shrimp waste) using a chemical modification approach. The produced biosorbents were used to recover cerium ions from aqueous mediums. The affinity of the adsorbents towards cerium was tested in batch systems under different experimental conditions. The biosorbents showed high affinities for cerium ions. The percentage of cerium ions removed (%) from its aqueous system by polyamines and polycarboxylate chitosan sorbents is 85.73 and 90.92 %, respectively. The results indicated that the biosorbents have a high biosorption capacity for cerium ions from aqueous and leach liquor streams.

Characteristics and provenances of rare earth elements and Nd isotopes in surface sediments of mangrove wetlands in the Jiulong River Estuary, China

Rare earth elements (REEs) and Nd isotopes are frequently employed to determine provenance, although their characteristics and provenances in the surface sediments of mangrove wetlands are rarely analyzed. In this study, a thorough analysis of the characteristics and provenances of REEs and Nd isotopes in the surface sediments of mangrove wetland in the Jiulong River Estuary was carried out. According to the results, the mean concentration of REEs in the surface sediments was 290.9 mg·kg-1, which was greater than the background value. Unpolluted to moderately polluted for La and Ce, as well as a moderate ecological risk for Lu, were indicated by the geoaccumulation index (Igeo) and potential ecological risk of individual factors ([Formula: see text]), respectively. The surface sediments showed substantial negative Eu anomalies but no significant Ce anomalies. The enrichments in LREE and flat HREE patterns are visible in the chondrite-normalized REE patterns. REEs in the surface sediments might be attributed to both natural sources (granite and magmatic rocks) and anthropogenic activities, including coal combustion, vehicle exhaust, steel smelting, and fertilizer, based on the (La/Yb)N-∑REE and ternary (La/Yb)N-(La/Sm)N-(Gd/Yb)N plots. The three-dimensional ∑LREE/∑HREE-Eu/Eu*-εNd(0) plot, when combined with the Nd isotope, further demonstrated that the REEs in the surface sediments appeared to have come from additional nonlocal potential sources.

Biointeraction of cerium oxide and neodymium oxide nanoparticles with pure culture methylobacterium extorquens AM1

Rare earth elements (REE) are valuable raw materials in our modern life. Extensive REE application from electronic devices to medical instruments and wind turbines, and non-uniform distribution of these resources around the world, make them strategically and economically important for countries. Current REE physical and chemical mining and recycling methods could have negative environmental consequences, and biologically-mediated techniques could be applied to overcome this issue. In this study, the bioextraction of cerium oxide and neodymium oxide nanoparticles (REE-NP) by a pure culture Methylobacterium extorquens AM1 (ATCC®14718™) was investigated in batch experiments. Results show that adding up to 1000 ppm CeO₂ or Nd₂O₃ nanoparticles (REE-NP) did not seem to affect the bacterial growth over 14-days contact time. Effect of methylamine hydrochloride as an essential electron donor and carbon source for microbial oxidation and growth was also observed inasmuch as there was approximately no growth when it does not exist in the medium. Although very low concentrations of cerium and neodymium in the liquid phase were measured, concentrations of 45 μg/g_cell Ce and 154 μg/g_cell Nd could be extracted by M. extorquens AM1. Furthermore, SEM-EDS and STEM-EDS confirmed surface and intracellular accumulation of nanoparticles. These results confirmed the ability of M. extorquens to accumulate REE nanoparticles.

Rare earths release from dissolving atmospheric dust and their accumulation into crystallising halite: The Dead Sea example

The industrial extraction of Y and lanthanides (hereafter defined as Rare Earth Elements, REE) often requires the achievement of leaching procedures removing these metals from primary rocks and their transfer in aqueous leachates or incorporated in newly forming soluble solids. These procedures are the most dangerous to the environment in relation to the composition of leachates. Hence, the recognition of natural settings where these processes currently occur, represents a worthy challenge for learning how to carry out similar industrial procedures under natural and more eco-friendly conditions. Accordingly, the REE distribution was studied in the brine of Dead Sea, a terminal evaporating basin where brines dissolve atmospheric fallout particles and crystallise halite. Our results indicate that the shale-like fractionation of shale-normalised REE patterns in brines, inherited during the dissolution of atmospheric fallout, changes because of the halite crystallisation. This process leads to crystallising halite mainly enriched in elements from Sm to Ho (medium REE, MREE) and coexisting mother brines enriched in La and some other light REE (LREE). We suggest that the dissolution of atmospheric dust in brines corresponds to the REE extraction from primary silicate rocks, whereas halite crystallisation represents the REE transfer into a secondary more soluble deposit with reduced environmental health outcomes.

Uranium and lanthanum in Norwegian drinking water - Is there cause for concern?

Due to natural conditions such as geology, topography, and climate, and historical features such as resource utilization, land use, and settlement patterns, the drinking water supply in Norway is separated into many public and private water supply systems. This survey sheds light on whether the Drinking Water Regulation's limit values provide a sufficient basis for ensuring safe drinking water for the Norwegian population. Participating waterworks, both private and public, were spread throughout the country, in 21 municipalities with different geological conditions. The median value for the number of persons supplied by the participating waterworks was 155. The two largest waterworks, both of which supply >10,000 people, have water sources from unconsolidated surficial sediments of latest Quaternary age. Fourteen waterworks have water sources from bedrock aquifers. Raw and treated water were analysed for 64 elements and selected anions. The concentration of manganese, iron, arsenic, aluminium, uranium, and fluoride exceeded the respective drinking water regulations' parametric value given in Directive (EU) 2020/2184. Regarding the rare earth elements, neither WHO, EU, USA nor Canada have established any limit values. However, concentration of lanthanum in groundwater from a sedimentary well exceeded the health-based guideline value that applies in Australia. Results from this study raise the question of whether increased precipitation can have an impact on the mobility and concentration of uranium in groundwater from bedrock aquifers. Furthermore, findings of high levels of lanthanum in groundwater create uncertainty as to whether the current quality control of Norwegian drinking water is sufficient.

Foliar application of lanthanum promotes growth and phytoremediation potential Solanum nigrum L

The hormetic effect of rare earth elements (REEs) has been found in a variety of crops and has been promoting crop growth for decades. Spraying leaves with REEs can enhance the endocytosis of plant roots. The non-selectivity of endocytosis is conducive to the direct absorption of environmental pollutants. The hyperaccumulator Solanum nigrum L. (S. nigrum), as a plant with high biomass and heavy metal tolerance, is a good candidate for phytoremediation. La(III), as a typical light REE, also has an obvious hormetic effect on S. nigrum. At 10 μM La(III), the biomass of S. nigrum reached the maximum, which was 89% greater than the control, and La(III) concentration was much lower than the previously reported optimum of 56 μM for general plants. In the present study, enhanced endocytosis after foliar spraying of La(III) was firstly observed in the root cell of hyperaccumulation plants, and La(III) increased the biomass of S. nigrum by improving the photosynthetic system, and promoting nutrient uptake and root development. The antioxidant defense system improved by La(III) contributed to the tolerance of S. nigrum to heavy metals. Applying a reasonable range of La(III) is beneficial to improving S. nigrum growth and tolerance of heavy metals. Compared with spraying deionized water, the translocation factor and bioaccumulation factor value of S. nigrum to cadmium increased by 15% and 21% respectively when spraying 10 μM La(III). Our findings provide a reference for improving hyperaccumulator plant growth and biomass, which improves phytoremediation efficiency.