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An Overview of Extraction Schemes for the Recovery of Erbium
Published in Abhilash, Ata Akcil, Critical and Rare Earth Elements, 2019
Shivendra Sinha, Abhilash, Pratima Meshram
Erbium being a critically important REE has immense applications in several technologically advanced areas, particularly in fusion reactors which require high purity erbium oxide/erbium-based compounds. However, its low concentration in monazite and xenotime deposits coupled with the presence of chemically similar elements make the task of devising separation schemes extremely tedious. This is corroborated by previous studies vis-à-vis separation processes such as solvent extraction, adsorption/IIPs, and electrolysis. There exists a lacunae in terms of selectivity, separation factor, ease of operation, low energy, and material costs, where research efforts can be aligned. To achieve high selectivity, molecular modeling and ab-initio modeling can be used by the simulation of erbium ion-selective functional moieties, which preferentially take erbium over other lanthanides. This approach can be extended to the design of new solvents, adsorbents, and IIP. Moreover, solvent-assisted membrane separation can also be promising in terms of augmenting the separation factor values. However, the cost of operation needs to be taken into account to achieve this new synthesized molecule to the tune of technological level. Considering the global demand for REOs, which was estimated to be 150,766 tons in 2020 at a CAGR of 3.8% due to escalating demands, research efforts in a modern circular economy are aligned to utilize end-of-life products; therefore, efforts can be made for the extraction of erbium from such products. Moreover, it was also seen that the potential of existing solvents, IIPs, and adsorbents are not yet fully explored from dilute solutions of erbium with other similar lanthanides and metal ions. Such studies will certainly help in the selection of separation schemes while utilizing end-of-life products.
Rare Earth Materials Best Suited for RF and EO Devices and Systems
Published in A. R. Jha, Deployment of Rare Earth Materials in Microware Devices, RF Transmitters, and Laser Systems, 2019
Erbium (Er): this rare earth material is a critical element widely used in the design and development of fiber optic transmission cables and fiber optic amplifiers, where superior overall performance and minimum transmission losses are of serious concern. Optical engineers believe that these fiber optic amplifiers offer an optimum as well as stable gain over wider spectral bandwidths under harsh operating conditions. Er-based optical crystals [1] are widely used in the design of dual-valence and trivalent laser systems such as Er:YLF (erbium-yttrium-lithium-fluoride) and Er:Ho:YLF (erbium-holmium-ytterbium-lithium-ferrite) rare earth–doped crystals, which are classified as dual-valence and trivalent optical linear crystals. It is interesting to point out that rare earth nonlinear crystals generally yield poor conversion efficiencies. It should be further noted that higher differential quantum efficiency, enhanced electrical-to-optical efficiency, and improved beam quality with minimum cost and complexity are possible through optimum pumping schemes. There are two different pumping schemes, namely, diode-pumping and lamp-pumping schemes. Note that tradeoff studies must be undertaken to determine which pumping scheme will offer lower cost and complexity. It is interesting to mention that the tradeoff studies undertaken by the author seem to indicate that the lamp-pumping scheme would be ideal for lasers demanding higher optical power output. However, this particular scheme would not yield minimum weight and size of the package. Research studies undertaken by the author reveal that the lamp-pumping scheme could deliver CW power output greater than 500 mW over 3.9 to 4.1 micron range when operating under cryogenic conditions [2]. Note that higher CW power output levels have been observed under the lamp-pump scheme compared to the solid state pumping scheme. In general, rare earth nonlinear crystals offer low conversion efficiency under room-temperature environment. However, significantly higher conversion efficiencies have been observed at cryogenic temperatures, which will increase the cost and package dimensions besides causing poor reliability.
Synergistic Solvent Extraction of Erbium(III) using a Mixture of Neodecanoic Acid with 1-(2-Neononylamidoethyl)-2-Neononyl-2-Imidazoline
Published in Solvent Extraction and Ion Exchange, 2023
Svetlana Bondareva, Yury Murinov
As with effect of diluents on Er(III) extraction, preliminary pH dependencies for the extraction of Er(III) were performed at relatively low concentration of extractants compared to erbium concentration (Figure 3). With NNI alone, the extraction of erbium is negligible and accompanied by the formation of a third phase in the extraction system. With HA alone, efficient extraction of erbium is reached in a relatively narrow pH range, and with increasing pH, precipitation of erbium hydroxide appears. The addition of NNI to the HA solution led to the enhancement of Er(III) extraction and the increase in the pH range of effective extraction. A synergistic enhancement coefficient (R) is dependent upon the equilibrium pH of the aqueous phase; in the equilibrium pH range between 6.0 and 6.5, R has been estimated to be 2.5–3.0. Almost the same values of R were obtained at molar ratio HA:NNI = 2:1 and 1:1. Accordingly, the synergistic effect observed can be explained by the formation of hydrophobic adducts 2 HA·NNI or/and HA·NNI in organic phase, which increase the extraction of erbium.