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- Simões Dos Reis, Glaydson
(författare)
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Biosorption of Neodymium (Nd) from Aqueous Solutions Using Spirulina platensis sp. Strains
- 2022
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Ingår i: Polymers. - : MDPI AG. - 2073-4360. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- Rare earth elements such as neodymium (Nd) are important elements used mainly in developing new technologies. Although they are found in low concentrations in nature, they can be obtained by extracting solid samples such as phosphogypsum. Among the techniques, adsorption has been used successfully with several adsorbent materials. In this work, two strains of Spirulina platensis (LEB-18 and LEB-52) were employed as biosorbents for efficiently removing the Nd element from the aqueous media. Biosorption tests were carried out in a batch system, and the results of the biosorption kinetics showed that for both materials, the biosorption of Nd was better described by the Avrami model. Moreover, it could be considered that 80 min would be necessary to attain the equilibrium of Nd(III) using both biosorbents. The result of the biosorption isotherms showed that for both strains, the best-fitted model was the Liu model, having a maximum biosorption capacity of 72.5 mg g(-1) for LEB-18 and 48.2 mg g(-1) for LEB-52 at a temperature of 298 K. Thermodynamics of adsorption showed that for both LEB-18 and LEB-52 the process was favorable ( increment G degrees < 0) and exothermic ( increment H degrees -23.2 for LEB-18 and increment H degrees -19.9 for LEB-52). Finally, both strains were suitable to uptake Nd, and the better result of LEB-18 could be attributed to the high amount of P and S groups in this biomass. Based on the results, a mechanism of electrostatic attraction of Nd3+ and phosphate and sulfate groups of both strains of Spirulina platensis was proposed.
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| 3. |
- Kessler, Vadim, et al.
(författare)
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Recovery of rare earth elements from NdFeB magnet by mono- and bifunctional mesoporous silica: Waste recycling strategies and perspectives
- 2022
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Ingår i: Hydrometallurgy. - : Elsevier BV. - 0304-386X. ; 210
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Tidskriftsartikel (refereegranskat)abstract
- Rare earth elements (REEs) such as Nd3+ and Dy3+ were recovered from simulated and real leaching solution of the NdFeB magnet via solid phase extraction (SPE). Extraction of REEs from simulated solutions was investigated using silica functionalized with NH2-, EDTA and/or phosphonic groups. The effects of several experimental factors (pH, efficiency of adsorbents, selectivity, and elution of metal ions) on extraction of REEs were investigated. Exploiting specific affinities of adsorbents toward REEs in the presence of competing ions, selective separation of REEs was achieved successfully. The affinity of phosphorous/nitrogen containing adsorbents had the descending order of adsorption: Fe3+ > Dy3+ > Nd3+ > Ni2+ > Al3+ for multi-component systems. In the first approach, a procedure based on precipitation of Fe3+ ions combined with SPE was evaluated for the recovery of REEs in two steps. Most of the Fe3+ ions (85%) were efficiently separated by adding an ammonia solution (pH ~ 2.5). Chemical analysis of precipitate showed, though, a high content of REEs. Extraction of REEs from supernatant liquid via bi-functional mesoporous silica with EDTA and/or phosphonic groups recovered ~97.0% of Nd3+ with Ni2+ and Al3+ ions as impurities. Non-ordered silica functionalized with phosphonic groups, showed economical superiority over other mesoporous adsorbents studied for REEs extraction. Complete recovery (97.8%) of REEs was achieved after several stages of SPE with adsorbents functionalized by P/N-containing groups. The in-advance removal of Fe3+ ions was a prerequisite for successful implementation of this approach. Finally, separation of Nd3+ and Dy3+ was performed from nitric acid media using the gradient elution to obtain 98.4% purity Nd3+. The proposed step-by-step SPE procedure by P/N-containing functionalized silica was successfully applied for extraction of REEs (95.5%) in an industrial magnet. This study opens up possibilities for application of the developed approach for the End-of-Life materials recycling.
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