Holmium nitrate complexation with tri-n-butyl phosphate in supercritical carbon dioxide

Fox, Robert V.; Ball, R. D.; Harrington, Peter de B.; Rollins, Harry W.; Wai, Chien M.

doi:10.1016/j.supflu.2005.05.003

Cited by 17 publications

(15 citation statements)

References 24 publications

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“…Ligand chemistry and coordination geometry of REEs are major factors determining the type of agent to be utilized in SCFE. There have been several studies that investigated SCFE of REEs from solid matrices and liquid solutions, an overview of which is presented in Table . − …”

Section: Introductionmentioning

confidence: 99%

Supercritical Fluid Extraction of Rare Earth Elements from Nickel Metal Hydride Battery

Yao¹,

Farac²,

Azimi

2017

ACS Sustainable Chem. Eng.

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Today's world relies upon critical green technologies that are made of elements with unique properties irreplaceable by other materials. Such elements are classified under strategic materials; examples include rare earth elements that are in increasingly high demand but facing supply uncertainty and near zero recycling. For tackling the sustainability challenges associated with rare earth elements supply, new strategies have been initiated to mine these elements from secondary sources. Waste electrical and electronic equipment contain considerable amounts of rare earth elements; however, the current level of their recycling is less than 1%. Current recycling practices use either pyrometallurgy, which is energy intensive, or hydrometallurgy that rely on large volumes of acids and organic solvents, generating large volumes of environmentally unsafe residues. This study put emphasis on developing an innovative and sustainable process for the urban mining of rare earth elements from waste electrical and electronic equipment, in particular, a nickel metal hydride battery. The developed process relies on supercritical fluid extraction utilizing CO 2 as the solvent, which is inert, safe, and abundant. This process is very efficient in the sense that it is safe, runs at low temperature, and does not produce hazardous waste while recovering ∼90% of rare earth elements. Furthermore, we propose a mechanism for the supercritical fluid extraction of rare earth elements, where we considered a trivalent rare earth element state bonded with three tri-n-butyl phosphate molecules and three nitrates model for the extracted rare earth tri-n-butyl phosphate complex. The supercritical fluid extraction process has the double advantage of waste valorization without utilizing hazardous reagents, thus minimizing the negative impacts of process tailings.

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Section: Introductionmentioning

confidence: 99%

Supercritical Fluid Extraction of Rare Earth Elements from Nickel Metal Hydride Battery

Yao¹,

Farac²,

Azimi

2017

ACS Sustainable Chem. Eng.

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“…It is usually in the form of pentahydrate. It is soluble in water and stable in air, and therefore is a suitable precursor for various chemical reactions (Yan and Chen, 2001; Fox et al , 2005).…”

Section: Introductionmentioning

confidence: 99%

X-ray powder diffraction data for holmium nitrate pentahydrate

Maixner

Bartůněk

2012

Powder Diffr.

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X-ray powder diffraction data, unit-cell parameters, and space group for the holmium nitrate pentahydrate Ho(NO3)3•5H2O are reported [a = 6.642(8) Å,b = 9.55(2) Å,c = 10.56(2) Å,α = 63.672(1)°,β = 84.622(2)°,γ = 76.085(2)°, unit-cell volumeV = 582,74 Å3,Z = 2, space groupP-1]. Ho(NO3)3•5H2O is isostructural with ytrium nitrate pentahydrate (PDF 01-75-2104) (ICDD, 2011). All measured lines were indexed and are consistent with theP-1 space group. No detectable impurities were observed.

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“…REEs can be extracted in supercritical CO 2 as a TBP/nitrate complex in several different ways. Supercritical CO 2 with TBP has been used to extract REEs (and actinides) from aqueous nitrate solutions [8][9][10] and from solid nitrate salts [11][12][13]. Another option is to premix TBP and HNO 3 to form a liquid adduct, dissolve this adduct in supercritical CO 2 , and use this modified CO 2 to extract REEs from acid-soluble mineral phases such as oxides [14][15][16][17][18][19].…”

Section: Supercritical Fluid Extractionmentioning

confidence: 99%

Rare earth element extraction from pretreated bastnäsite in supercritical carbon dioxide

Sinclair

Baek

Thompson

et al. 2017

The Journal of Supercritical Fluids

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Holmium nitrate complexation with tri-n-butyl phosphate in supercritical carbon dioxide

Cited by 17 publications

References 24 publications

Supercritical Fluid Extraction of Rare Earth Elements from Nickel Metal Hydride Battery

Supercritical Fluid Extraction of Rare Earth Elements from Nickel Metal Hydride Battery

X-ray powder diffraction data for holmium nitrate pentahydrate

Rare earth element extraction from pretreated bastnäsite in supercritical carbon dioxide

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