Rare earth elements: A review of applications, occurrence, exploration, analysis, recycling, and environmental impact

Balaram, V.

doi:10.1016/j.gsf.2018.12.005

Cited by 1,311 publications

(741 citation statements)

References 140 publications

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“…Las tierras raras no se encuentran en la naturaleza en forma libre, como otros elementos; se hallan en minerales muy específicos como la allanita, la loparita, la parisita, la apatita, la monazita y otros (Balaram, 2018). Durante la Segunda Guerra Mundial fueron contaminantes de los materiales fisionables necesarios para fabricar la bomba atómica; esos conocimientos de los procesos de separación son la base para producirlos a escala industrial actualmente, y se basan fundamentalmente en el intercambio iónico (American Chemical Society, 1999).…”

Section: Tierras Raras Ni Tan Raras Ni Tan Escasasunclassified

“…Mas allá del poder energético generado por las tierras raras, estas hacen parte importante del equilibrio tecnológico, económico y político del mundo. En China se concentra más del 70 % de la producción mundial, cifra que algunos ubican hasta en un 90 %, aunque tiene un poco más del 30 % de las reservas mundiales (Balaram, 2018). Para 1987, el dirigente chino Deng Xiao Ping hizo la primera adver-tencia del potencial de las tierras raras: "Occidente tiene petróleo.…”

Section: Las Tierras Raras Como Fuente De Poderunclassified

“…Visto que en una cadena de producción no se puede sustituir súbitamente un elemento químico por otro y que poner a funcionar una mina es tarea de casi un decenio, la opción más inmediata parece ser reciclar las tierras raras (Balaram, 2018;Binnemans, et al, 2013), lo que no es fácil, porque ya está comprobada la dificultad para separarlos entre sí. Por otra parte, también se exploran otras fuentes como las minas de fertilizantes de fosfatos y los residuos de la combustión del carbón y de procesos nucleares.…”

Section: Las Tierras Raras Como Fuente De Poderunclassified

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Los lantánidos: ni tierras ni raras

Parra

2019

Rev. Acad. Colomb. Cienc. Ex. Fis. Nat.

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ResumenLa tabla periódica de los elementos contiene la base fundamental del conocimiento pasado, presente y futuro de la Química. Sin embargo, aún se proponen modelos adicionales y complementarios para tratar de satisfacer todas y cada una de las propiedades físicas y químicas, en especial de aquellos elementos que actualmente no se ajustan a ella. Algunas de esas desviaciones seguramente tendrán explicaciones por aproximaciones cuánticas, obviamente desconocidas en el tiempo de la propuesta original. Específicamente, existen dos situaciones relevantes clásicas, relacionadas con las tierras raras y los actínidos, que involucran unos 30 elementos. Estos se muestran como anexos por fuera del orden previsto y, por sus características de grupos, se organizan como períodos. A pesar de los debates en torno a la reubicación de dichos elementos, que realmente no es un mero ejercicio académico, las tierras raras son valiosos materiales con múltiples aplicaciones en la vida diaria y, además, tienen un papel fundamental en el equilibrio económico y político mundial. En este artículo se presentan varios aspectos relacionados con su posición en la tabla periódica, así como las propiedades estructurales y electrónicas de sus favorables y anómalos comportamientos, sus aplicaciones y el contexto internacional por la hegemonía mundial basada en el uso de sus elementos. AbstractThe periodic table of elements contains the fundamental basis of past, present, and future knowledge of Chemistry. However, additional and complementary models are still proposed to try to satisfy the unique physical and chemical properties of those that do not conform to it. Some of these questions will surely have explanations based on quantum approaches, obviously unknown in the time of the original proposal. In the periodic table, there are two typical relevant situations related to rare lands and actinides, involving about 30 elements. These are displayed as annexes outside the intended order and having group characteristics, they are organized as periods. Despite discussions regarding the relocation of these elements, which is not an irrelevant academic exercise, rare earths are now valuable materials with multiple applications and they have a fundamental role in economic balance and global politics. This article presents several aspects related to their position in the periodic table, as well as the structural and electronic properties of their favorable and unusual behaviors, their applications, and the international context for global hegemony founded on this type of elements.

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Section: Tierras Raras Ni Tan Raras Ni Tan Escasasunclassified

Section: Las Tierras Raras Como Fuente De Poderunclassified

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Los lantánidos: ni tierras ni raras

Parra

2019

Rev. Acad. Colomb. Cienc. Ex. Fis. Nat.

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“…The REEs are extensively applied in fertilizers due to their function of improving the quality and yield of crops [12]. As rare earth elements are widely used, REE mining has boomed all around the world over the years, and Thailand is one of the main countries producing rare earth elements [13]. Moreover, the study area is located in northeast Thailand, which is a large agricultural region where huge amounts of fertilizers are applied every year [14].…”

Section: Introductionmentioning

confidence: 99%

Geochemical Distribution Characteristics of Rare Earth Elements in Different Soil Profiles in Mun River Basin, Northeast Thailand

et al. 2020

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Exploring the distributions of rare earth elements (REEs) in soil profiles is essential to understanding how natural and anthropogenic factors influence the geochemical behaviors of REEs. This study aimed to learn about the distribution characteristics of REEs in soils, including their fractionation and enrichment, and to explore the influence of soil pH and soil organic carbon (SOC) on REEs. One hundred and three samples were collected from six soil profiles under different land uses (paddy field: T1, T3; forest land: T2, T6; wasteland: T4; building site: T5) in the Mun River Basin, Northeast Thailand. The average total REE contents (∑REE) are much lower (<80 mg kg−1) than that of Earth’s crust (153.80 mg kg−1) in soil profiles T2, T3, T4, and T6. The contents of REEs tend to increase slightly with depth in all soil profiles. The ratios of (La/Yb)N range from 0.35 to 0.96 in most samples, indicating that the enrichment of heavy REEs (HREEs) relative to light REEs (LREEs) is the main fractionation pattern. Samples from profile T2 show relatively obvious negative Ce anomalies (0.55–0.78) and positive Eu anomalies (1.41–1.56), but there are almost no anomalies of Ce and Eu in other soil profiles. Enrichment factors of LREEs (EFLREEs) range from 0.23 to 1.54 and EFHREEs range from 0.34 to 2.27, which demonstrates that all soil samples show no LREE enrichment and only parts of samples show minor HREE enrichment. Soil organic carbon (SOC) contents positively correlate with the enrichment factors of REEs (EFREE) in soil profiles T1 (R = 0.56, p < 0.01) and T6 (R = 0.71), while soil pH values correlate well with EFREE in soil profiles T2 (R = 0.75) and T4 (R = −0.66, p < 0.01), indicating the important influence of soil pH and SOC on the mobility of REEs in some soil profiles.

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“…In the pursuit of new materials, current research has concentrated on white light generation using luminescent organic molecules, polymers with red‐green‐blue (RGB) emitting side chains, three‐layer RGB molecular system, hybrid perovskites, supramolecular polymers, and lanthanide‐based phosphor‐converted white light‐emitting diodes 4–8. In the case of phosphor‐converted white light‐emitting diodes (LEDs), phosphors are composed of rare‐earth elements that not only are of a limited supply, but also pose health hazards9 and serious environmental impact 10. In the light of this, there is an urgent need to develop and discover alternative materials to enable next generation solid‐state lighting applications.…”

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Dual‐Guest Functionalized Zeolitic Imidazolate Framework‐8 for 3D Printing White Light‐Emitting Composites

Chaudhari

Tan

2020

Advanced Optical Materials

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The self-assembly of metal-organic frameworks (MOFs) or porous coordination polymers (PCPs) in an orderly fashion to form periodic framework structures offers several advantages. [11][12][13] More recently, researchers are exploring the use of periodic chemically-active molecular spaces found in the nanoscale pores of MOFs/PCPs (acting as a "host" framework) to confine a range of functional "guest" species or molecular complexes. The guest confinement approach yields a guest-host system termed "Guest@ MOF" [14] that can be useful as an electrical conductor, [15,16] light-emitting material, [17][18][19] selective gas/analyte sorbent, drug carrier, and chemical sensors. [20,21] For example, we have been working on a number of Guest@MOF systems to develop tuneable luminescent materials for photonics-based sensing applications. [22][23][24] In our studies, we found that the high concentration reaction (HCR) protocol is advantageous for: i) rapid one-pot synthesis of nano-MOFs (e.g., nanosheets and nanostructures), ii) in situ encapsulation of bulky guest molecules or nanoconfinement of metal complexes, and iii) high yield of end products under ambient conditions. [22] These characteristics are the main requirements for constructing a functional material via facile guest confinement, with easy processability and future industrial-scale synthesis.There is an increasing number of studies on Guest@MOF research reporting the encapsulation of a wide range of functional guests, such as rare-earth metals, organic dyes, carbon dots, quantum dots, and metal complexes to achieve tuneable luminescent properties and white light generation. [17][18][19][25][26][27][28][29][30][31][32] Indeed, the majority of current efforts are much dependent on the use of non-economical and non-environmentally friendly rare-earth metals, see the statistics in Figure S1, Supporting Information. Additionally, recent examples of synthetic method adopted for constructing tuneable luminescent systems require multistep core-shell processing to yield multivariate guest encapsulation, [33] which may be challenging to translate from lab to practical applications.Herein we demonstrate the use of the HCR approach to accomplish the in situ multi-guest encapsulation of two fluorescent dye species (rare-earth free guests), being nanoconfined within the sodalite cage of the ZIF-8 framework via a one-pot reaction under ambient conditions. First, we present the facile synthesis and detailed characterization of the previously unreported Metal-organic frameworks (MOFs) stand as a promising chemically active host scaffold for the encapsulation of functional guests, because they could enhance luminescent properties by molecular separation of fluorophores in the nanoscale pores of the MOF crystals. Herein, simultaneous nanoconfinement of two fluorophores is shown, namely, A) fluorescein and B) rhodamine B in the sodalite cages of ZIF-8, constructed under ambient conditions through a simple one-pot reaction. A novel Dual-Guest@MOF system is reported, termed: A+B@ZIF-8,...

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Rare earth elements: A review of applications, occurrence, exploration, analysis, recycling, and environmental impact

Cited by 1,311 publications

References 140 publications

Los lantánidos: ni tierras ni raras

Los lantánidos: ni tierras ni raras

Geochemical Distribution Characteristics of Rare Earth Elements in Different Soil Profiles in Mun River Basin, Northeast Thailand

Dual‐Guest Functionalized Zeolitic Imidazolate Framework‐8 for 3D Printing White Light‐Emitting Composites

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