| 1. |
- Ashour, Radwa, et al.
(författare)
-
DTPA-Functionalized Silica Nano- and Microparticles for Adsorption and Chromatographic Separation of Rare Earth Elements
- 2018
-
Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 6:5, s. 6889-6900
-
Tidskriftsartikel (refereegranskat)abstract
- Silica nanoparticles and porous microparticles have been successfully functionalized with a monolayer of DTPA-derived ligands. The ligand grafting is chemically robust and does not appreciably influence the morphology or the structure of the material. The produced particles exhibit quick kinetics and high capacity for REE adsorption. The feasibility of using the DTPA-functionalized microparticles for chromatographic separation of rare earth elements has been investigated for different sample concentrations, elution modes, eluent concentrations, eluent flow rates, and column temperatures. Good separation of the La(III), Ce(III), Pr(III), Nd(III), and Dy(III) ions was achieved using HNO3 as eluent using a linear concentration gradient from 0 to 0.15 M over 55 min. The long-term performance of the functionalized column has been verified, with very little deterioration recorded over more than 50 experiments. The results of this study demonstrate the potential for using DTPA-functionalized silica particles in a chromatographic process for separating these valuable elements from waste sources, as an environmentally preferable alternative to standard solvent-intensive processes.
|
|
| 2. |
- Alemrajabi, Mahmood, 1989-
(författare)
-
Recovery of Rare Earth Elements from an Apatite Concentrate
- 2018
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Rare earth elements (REE) are a group of 17 elements including lanthanides, yttrium and scandium; which are found in a variety of classes of minerals worldwide. The criticality of the application, lack of high grade and economically feasible REE resources and a monopolistic supply situation has raised significant attention in recovery of these metals from low grade ores and waste materials. In this thesis, the recovery of REE from an apatite concentrate, containing 0.5 mass% of REE, within the nitrophosphate route of fertilizer production has been investigated. Most of the REE (≥ 95%) content can be recovered into a phosphate precipitate with almost 30 mass% REE. Different processes have been developed to convert the REE phosphate precipitate into a more soluble form to obtain a solution suitable for further REE purification and individual separation. It has been shown that after reprecipitation of the REE phosphate concentrate as REE sodium double sulphate and then transformation into a REE hydroxide concentrate, a solution containing 45g/L REE free of Ca, Fe and P can be obtained. The results suggest that the apatite waste after processing of iron ore have the potential to be a very important source for REE in Europe and that the economy is strongly supported by the simultaneous extraction of phosphorous.The potential of using hollow fiber supported liquid membrane (HFSLM) extraction in individual and group separation of REE has been investigated. A hollow fiber supported liquid membrane plant in pilot scale has been operated according to the three main configurations: standard hollow fiber supported liquid membrane technology (HFSLM); hollow fiber renewal liquid membrane technology (HFRSLM) and emulsion pertraction technology (EPT). The standard HFSLM operation is more selective than HFRSLM and EPT, while higher metal transport rate is observed in EPT followed by HFRSLM and HFSLM. The HFRLM configuration helps to maintain the performance of the liquid membrane.
|
|
| 3. |
- Korkmaz, Kivanc
(författare)
-
Recovery of Rare Earth Elements from spent Nickel-Metal Hydride Batteries from Hybrid Electric Vehicles
- 2021
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Rare earth elements (REE) are a group of elements that are of critical importance in numerous technological applications, including “green technologies” such as wind turbines and hybrid car batteries. When the criticality of applications is considered, problems in supply has brought the option of effective secondary resource utilization into consideration. In this thesis, several methods have been developed and assessed to recover REE from spent hybrid electric vehicles batteries.Leaching of the NiMH active anode and cathode materials with sulfuric acid and hydrochloric acid has been carried out. Acid recovery using nanofiltration has been investigated. Further, precipitation of a mixed REE concentrate has been studied. The REE were separated as sodium double sulfate salts after sulfuric acid leaching by addition of a sodium salt. In addition, antisolvent precipitation of REE sulfates were studied by addition of alcohols. The REE sulfate salts can easily be dissolved for further processing and recovery of the individual elements by other techniques. As an alternative a process based on sulfation, selective roasting and water leaching was investigated. This allowed recovering an aqueous REE sulfate solution also suitable for further processing to recover the individual REE by e.g. solvent extraction or chromatographic separation. A complimentary LCA study was conducted in collaboration with IVL. Here certain selected recycling methods were scaled up on paper and the environmental burdens of the different processes were compared. The results obtained have proven the effectiveness of different recycling methods. It is foreseen that Europe will be guiding the efforts on recycling whether it is supply problems or value creation and battery recycling will have key importance.The work proves the importance of sustainable and resource efficient technologies for closing the loop for critical raw materials. The sustainable development of these processes has substantial importance to have continuous and uninterrupted access to the critical raw materials as well as displaying a responsible method of recycling and consumption which are aligned with UN Global Goals for a sustainable society.
|
|
| 4. |
- Mealey, Donal, et al.
(författare)
-
Thermodynamics of risperidone and solubility in pure organic solvents
- 2014
-
Ingår i: Fluid Phase Equilibria. - : Elsevier. - 0378-3812 .- 1879-0224. ; 375, s. 73-79
-
Tidskriftsartikel (refereegranskat)abstract
- The solid-liquid solubility of the thermodynamically stable form I of the drug risperidone has been determined by a gravimetric method in nine pure organic solvents in the temperature range 278.15-323.15 K. The melting temperature and associated enthalpy of fusion of risperidone form I has been determined by differential scanning calorimetry (DSC) to be 442.38 K and 43.94 kJ mol(-1), respectively. The heat capacity of the solid form I and the melt have been determined over a range of temperatures by temperature-modulated DSC, and extrapolated data has been used to calculate the Gibbs energy, enthalpy and entropy of fusion from ambient temperature up to the melting point. The ideal solubility within a Raoult's law framework is obtained from the Gibbs energy of fusion, and the solution activity coefficient at equilibrium in the nine solvents quantified. Solutions in all solvents exhibit positive deviation from Raoult's law, with the highest solubility (closest to ideality) in toluene, an aprotic apolar solvent. The solubility curves plotted in a van't Hoff graph show non-linear behaviour and are well-approximated by a second order polynomial.
|
|
| 5. |
- Soto, Rodrigo, et al.
(författare)
-
Ketoprofen Solubility in Pure Organic Solvents Using In Situ FTIR and UV-Vis and Analysis of Solution Thermodynamics
- 2021
-
Ingår i: Organic Process Research & Development. - : American Chemical Society (ACS). - 1083-6160 .- 1520-586X. ; 25:11, s. 2403-2414
-
Tidskriftsartikel (refereegranskat)abstract
- This work investigates the use of in situ process analytical technologies, namely, attenuated total reflectance Fourier transform infrared spectroscopy (ATR FTIR) and ATR UV-vis, coupled with a robust chemometric multivariate analysis approach for the determination of the solubility of ketoprofen in organic solvents within the temperature range of 273.15-303.15 K. Principal component analysis of the raw spectral data is applied along with multiple regression analysis and a stepwise regression procedure as the chemometric approach to build inferential models able to predict solubility data. For each solvent, the constructed models are used for solubility determinations and the results are compared with those previously determined by a gravimetric method. Both in situ FTIR and UV-vis render an accurate prediction of solubility data, with a notably high number of data points enabling the subsequent thermodynamic analysis. However, the accuracy of the solubility rendered from the spectroscopic analysis is not as accurate as by the gravimetric method at low temperatures. In addition, the experimental enthalpies of solution are determined by solution calorimetry and are found to be in a range of 18.6-32.4 kJ/mol in the different solvents. The order of solubility data obtained in the solvents studied is discussed in terms of the strength of the interactions with the ketoprofen carbonyl groups analyzed by the C=O frequency of the FTIR data and based on the solution thermodynamic data obtained. All solutions of the work are relatively nonideal, with activity coefficients deviating from unity and enthalpies of mixing deviating from zero. The thermodynamic analysis and results clearly show that calorimetric enthalpies of solution are theoretically and quantitatively different from the corresponding van't Hoff enthalpies of solution, and a detailed explanation is provided.
|
|
| 6. |
|
|
| 7. |
- Watterson, Samuel, et al.
(författare)
-
Thermodynamics of fenofibrate and solubility in pure organic solvents
- 2014
-
Ingår i: Fluid Phase Equilibria. - : Elsevier BV. - 0378-3812 .- 1879-0224. ; 367, s. 143-150
-
Tidskriftsartikel (refereegranskat)abstract
- Calorimetric data on the melting of 1-methylethyl 2-[4-(4-chlorobenzoyl)-phenoxyl-2-methylpropanoate (fenofibrate) and the heat capacity of the solid and the melt have been determined, from which the Gibbs energy, enthalpy and entropy of fusion are calculated. Solid-liquid solubility data have been collected by a gravimetric method in seven pure solvents (methanol, ethanol, 1-propanol, 2-propanol, ethyl acetate, acetonitrile, and acetone) across a range of temperatures. Fenofibrate is much more soluble in ethyl acetate, acetonitrile and acetone compared to alcohols. In the alcohols the solubility increases with aliphatic chain length. The Gibbs energy of fusion is used to estimate the activity of the solid within a Raoult's law framework. Except for ethyl acetate solutions which are almost ideal, solutions in all evaluated solvents exhibit positive deviation from Raoult's law, and in the alcohols the activity coefficient ranges up to 25. It is shown that the heat capacity component of the enthalpy of fusion is not negligible at room temperature, in spite of the proximity to the melting point, and furthermore that the temperature dependence of the activity coefficient in the saturated solution has a governing influence on the van't Hoff enthalpy of solution in acetonitrile and the alcohols. Crystals obtained by two different methods from a range of solvents have been analysed by PXRD, FTIR and NMR spectroscopy, TGA and DSC, and have in all cases been shown to consist of the stable polymorph (form l).
|
|
| 8. |
- Zeglinski, Jacek, et al.
(författare)
-
Probing Crystal Nucleation of Fenoxycarb from Solution through the Effect of Solvent
- 2019
-
Ingår i: Crystal Growth & Design. - : AMER CHEMICAL SOC. - 1528-7483 .- 1528-7505. ; 19:4, s. 2037-2049
-
Tidskriftsartikel (refereegranskat)abstract
- Induction time experiments, spectroscopic and calorimetric analysis, and molecular modeling were used to probe the influence of solvent on the crystal nucleation of fenoxycarb (FC), a medium-sized, flexible organic molecule. A total of 800 induction times covering a range of supersaturations and crystallization temperatures in four different solvents were measured to elucidate the relative ease of nucleation. To achieve similar induction times, the required thermodynamic driving force, RT In S, increases in the order: ethyl acetate < toluene < ethanol < isopropanol. This is roughly matched by the order of interfacial energies calculated using the classical nucleation theory. Solvent solute interaction strengths were estimated using three methods: solvent-solute enthalpies derived from calorimetric solution enthalpies, solvent-solute interactions from molecular dynamics simulations, and the FTIR shifts in the carbonyl stretching corresponding to the solvent solute interaction. The three methods gave an overall order of solvent solute interactions increasing in the order toluene < ethyl acetate < alcohols. Thus, with the exception of FC in toluene, it is found that the nucleation difficulty increases with stronger binding of the solvent to the solute.
|
|
| 9. |
- Aisling, Lynch, et al.
(författare)
-
Crystal Growth of Single Salicylamide Crystals
- 2019
-
Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 19:12, s. 7230-7239
-
Tidskriftsartikel (refereegranskat)abstract
- Growth of single salicylamide crystals was investigated in a nonstirred growth cuvette and on a rotating disk. In the growth cuvette the crystal growth rates were measured for both primary nucleated crystals and seed crystals manually inserted into the cuvette. In the rotating disk experiments multiple seed crystals were attached to a disk that was rotated in a supersaturated solution. The crystal growth rates in the length and width direction were precisely measured in situ for each individual crystal, and growth rates were also extracted for a specific crystal facet, that is, (200). In all cases, the growth rate was considerably faster in the rotating disk experiments, shown to be governed by surface integration. Solvent was found to impact the growth rates of the crystal facets in part by creating different surface features. The influence of the supersaturation on the crystal growth rate depended on the solvent; in general, an increasing trend was observed. At relatively low supersaturations, it was discovered that the growth process will focus on repairing morphological defects. Within the range of experimental conditions, the growth kinetics were strongly affected by the temperature as was further indicated by the relatively high activation energy values obtained. The crystal seed quality was found to have a substantial impact on the growth rate, with rougher crystals leading to quicker growth. A wide growth rate dispersion was obtained for both crystal growth methods, found to be reduced by using seed crystals with high quality, lower supersaturations, and also within certain solvents.
|
|
| 10. |
- Alemrajabi, Mahmood, 1989-, et al.
(författare)
-
Processing of a rare earth phosphate concentrate obtained in the nitrophosphate process of fertilizer production
- 2019
-
Ingår i: Hydrometallurgy. - : Elsevier. - 0304-386X .- 1879-1158. ; 189
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, different processes have been developed and applied to treat a rare earth phosphate concentrate obtained within the nitrophosphate process of fertilizer production. Methods to remove impurities such as Fe and Ca have been investigated as well as to separate the phosphorous and thereby facilitate dissolution of the rare earth elements (REE). These methods include thermal treatment with sodium hydroxide and sodium double sulphate precipitation with and without alkaline conversion, followed by selective dissolution in different acids. The proposed processes were compared and analyzed from the perspective of introducing an appropriate intermediate product for further individual REE separation. The results have shown that after thermal treatment with NaOH at 400 °C, the phosphorous can be removed from the rare earth phosphate concentrate by water leaching. Investigation of different REE phosphate concentrates demonstrated that mixed Ca and REE phases, e.g. REEmCan(PO4)3m+2n/3 and CaHPO4 are less likely to dephosphorize than REE(PO4).nH2O and FePO4.H2O under these conditions. The recovery of REE to a mild acidic solution is limited by the presence of remaining phosphate ions and by the formation of REE oxide phases during the thermal treatment. The results also show that a solution containing 40 g/L REE; free of phosphorous, calcium and iron can be obtained after reprecipitation of the rare earth phosphate concentrate as sodium rare earth double sulphates followed by alkaline conversion with sodium hydroxide and dissolution in nitric acid.
|
|
