Solubility of novel open-chain crown ether bridged diphosphates in supercritical carbon dioxide

Ren, Qilong; Duan, Di; Zhang, Hai; Su, Baogen; Zhang, Zhiguo; Bao, Zongbi; Yang, Yiwen

doi:10.1016/j.jct.2013.07.017

Cited by 7 publications

(7 citation statements)

References 34 publications

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“…An increasing residence time allows for longer degradation of the magnet particles, thus increasing Fe extraction, while at higher pressures the density of sc-CO 2 is higher; thus, it has a higher solvation power for Fe. 40,41 These results suggest that, while Fe extraction is controlled by the parameters that increase the magnet particle solubility in sc-CO 2 , the extraction of REEs is controlled by the degree of complexation of these ions with the TBP−HNO 3 adducts. 42 Because the overall Fe extraction was significantly (α = 0.05) lower than that of the REEs, it can be concluded that the Fe− CA complex is less soluble than the REE−CA complex; thus, it is more susceptible to break in high shear environments, i.e., at a higher agitation rate (X 5 ).…”

Section: ■ Resultsmentioning

confidence: 95%

“…Residence time ( X 3 ) and pressure ( X 2 ) had the most significant positive single-parameter effects on Fe extraction efficiency. An increasing residence time allows for longer degradation of the magnet particles, thus increasing Fe extraction, while at higher pressures the density of sc-CO 2 is higher; thus, it has a higher solvation power for Fe. , These results suggest that, while Fe extraction is controlled by the parameters that increase the magnet particle solubility in sc-CO 2 , the extraction of REEs is controlled by the degree of complexation of these ions with the TBP–HNO 3 adducts …”

Section: Resultsmentioning

confidence: 97%

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Aeriometallurgical Extraction of Rare Earth Elements from a NdFeB Magnet Utilizing Supercritical Fluids

Zhang¹,

Anawati²,

Yao³

et al. 2018

ACS Sustainable Chem. Eng.

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There is a global need for efficient and environmentally sustainable processes to close the life cycle loop of waste electrical and electronic equipment (WEEE) through recycling. Conventional WEEE recycling processes are based upon pyrometallurgy or hydrometallurgy. The former is energy-intensive and generates greenhouse gas (GHG) emissions, while the latter relies on large volumes of acids and organic solvents, thus generating hazardous wastes. Here, a novel “aeriometallurgical” process was developed to recycle critical rare earth elements, namely, neodymium (Nd), praseodymium (Pr), and dysprosium (Dy), from postconsumer NdFeB magnets utilized in wind turbines. The new process utilizes supercritical CO2 as the solvent, which is safe, inert, and abundant, along with the tributyl-phosphate–nitric acid (TBP–HNO3) chelating agent and 2 wt % methanol as a cosolvent. Nd (94%), Pr (91%), and Dy (98%) extraction was achieved with only 62% iron (Fe) coextraction and minimal waste generation. Fundamental investigations into the extraction mechanism demonstrated that metal ion charge has an important impact on the extraction efficiency. Fundamental investigations indicate that extraction proceeds by corrosion of the magnet particle’s surface layer. This work demonstrates that supercritical fluid extraction would find widespread applicability as a cleaner, a more sustainable option to recycle value metals from end-of-life products to enable the circular economy.

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Section: ■ Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 97%

Aeriometallurgical Extraction of Rare Earth Elements from a NdFeB Magnet Utilizing Supercritical Fluids

Zhang¹,

Anawati²,

Yao³

et al. 2018

ACS Sustainable Chem. Eng.

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“…41 On the contrary, increasing pressure at constant temperature increases the density as more CO 2 is pumped into the system, thus increasing the solubility and therefore the extraction efficiency. 41,42 Furthermore, increasing pressure improves the penetration of sc-CO 2 into deeper pores of the anode material, which ultimately results in a higher degree of complexation. 43 Increasing the residence time from 1 to 2 h increased the leaching efficiency (Figure 2, run 5) because longer residence time allows for the reaction to proceed toward completion, leading to higher REE extraction efficiency.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Because increasing temperature at constant pressure decreases the density ρ and A/T term in eq , it decreases the solubility of the solute, thus decreasing the extraction efficiency . On the contrary, increasing pressure at constant temperature increases the density as more CO 2 is pumped into the system, thus increasing the solubility and therefore the extraction efficiency. , Furthermore, increasing pressure improves the penetration of sc-CO 2 into deeper pores of the anode material, which ultimately results in a higher degree of complexation …”

Section: Results and Discussionmentioning

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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“…In this paper, the static cloud-point method is employed to measure the solubility of VEA in SC-CO 2 at temperatures of 308.15, 313.15, 318.15, 323.15, and 328.15 K and pressures of 8–15 MPa. Even though the cloud-point method appears to be limited to a range of compounds poorly soluble in pure SC-CO 2 , many researchers have still used it to measure the solubility of different solutes in the supercritical system. ,,, Although the supercritical fluid can be swept successively through the visible cell by using the dynamic method, it can only provide information on the light phase . Thus, the static cloud-point method is relatively convenient in this work.…”

Section: Introductionmentioning

confidence: 99%

Solubility of Vitamin E Acetate in Supercritical Carbon Dioxide: Measurement and Correlation

et al. 2017

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Vitamin E acetate (VEA) exhibits promising pharmacological action in the pharmaceutical and cosmetic industries. The solubility of VEA in supercritical carbon dioxide is measured to determine the cloud-point pressures in a highpressure variable-volume view cell at various temperatures (i.e., 308.15, 313.15, 318.15, 323.15, and 328.15 K) and pressures (8−15 MPa). The experimental results indicate that the solubility of VEA can be improved by increasing pressure and reducing temperature in the experimental range. Furthermore, four density-based semiempirical models are employed to correlate and predict the experimental results, including Chrastil, Kumar and Johnston (K-J), Bartle, and Mendez-Santiago and Teja (MST) equations. The theoretical calculation results are consistent with the determinatal results.

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Solubility of novel open-chain crown ether bridged diphosphates in supercritical carbon dioxide

Cited by 7 publications

References 34 publications

Aeriometallurgical Extraction of Rare Earth Elements from a NdFeB Magnet Utilizing Supercritical Fluids

Aeriometallurgical Extraction of Rare Earth Elements from a NdFeB Magnet Utilizing Supercritical Fluids

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

Solubility of Vitamin E Acetate in Supercritical Carbon Dioxide: Measurement and Correlation

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