| 1. |
- Ahuja, Dipali, et al.
(författare)
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Investigation of solid-liquid phase diagrams of the sulfamethazine-salicylic acid co-crystal
- 2019
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Ingår i: CrystEngComm. - : ROYAL SOC CHEMISTRY. - 1466-8033. ; 21:18, s. 2863-2874
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Tidskriftsartikel (refereegranskat)abstract
- The influence of temperature and solvent on the solid-liquid phase diagram of the 1 : 1 sulfamethazinesalicylic acid co-crystal has been investigated. Ternary phase diagrams of this co-crystal system have been constructed in three solvents: methanol, acetonitrile and a 7 : 3 (v/v) dimethylsulfoxide-methanol mixture, at three temperatures. The system exhibits congruent dissolution in acetonitrile and the co-crystal solubility has been determined by a gravimetric technique. The Gibbs energy of co-crystal formation from the respective solid components has been estimated from solubility data, together with the corresponding enthalpic and entropic component terms. The Gibbs energy of formation ranges from -5.7 to -7.7 kJ mol -1, with the stability increasing with temperature. In methanol and the DMSO-methanol mixture, the co-crystal dissolves incongruently. It is shown that the solubility ratio of the pure components cannot be used to predict with confidence whether the co-crystal will dissolve congruently or incongruently. The size of the region where the co-crystal is the only stable solid phase is inversely related to the pure component solubility ratio of salicylic acid and sulfamethazine.
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| 2. |
- Ahuja, Dipali, et al.
(författare)
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Solution and calorimetric thermodynamic study of a new 1:1 sulfamethazine-3-methylsalicylic acid co-crystal
- 2020
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Ingår i: CrystEngComm. - : Royal Society of Chemistry (RSC). - 1466-8033. ; 22:20, s. 3463-3473
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Tidskriftsartikel (refereegranskat)abstract
- A new 1:1 co-crystal of sulfamethazine (API, SMT) and 3-methylsalicylic acid (coformer, 3mSA) has been synthesized and its crystal structure solved by single crystal X-ray diffraction (XRD). The co-crystal has been thoroughly characterized by powder XRD, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The pure co-crystal could be synthesized by solvent drop grinding, cooling crystallization and slurry conversion co-crystallization. Ternary phase diagrams have been constructed in methanol and acetonitrile at 30 degrees C. The co-crystal exhibits incongruent dissolution in both solvents. The thermodynamics of co-crystal formation have been estimated from solubility data and calorimetric data, respectively, showing that formation of the SMT-3mSA co-crystal from its solid components is spontaneous and entropy-driven. The co-crystal formation is associated with a 5% increase in molecular volume. A relationship between the size of the region where the co-crystal is the most stable solid phase and the relative solubility of the co-crystal components has been uncovered. The co-crystal region becomes smaller as the solubility ratio increases.
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| 3. |
- Ashour, Radwa, et al.
(författare)
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DTPA-Functionalized Silica Nano- and Microparticles for Adsorption and Chromatographic Separation of Rare Earth Elements
- 2018
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Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 6:5, s. 6889-6900
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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.
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| 4. |
- Cheuk, Dominic, et al.
(författare)
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Thermodynamics of the Enantiotropic Pharmaceutical Compound Benzocaine and Solubility in Pure Organic Solvents
- 2020
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Ingår i: Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0022-3549 .- 1520-6017. ; 109:11, s. 3370-3377
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Tidskriftsartikel (refereegranskat)abstract
- The thermodynamic relationship between FI and FII of ethyl 4-aminobenzoate (benzocaine) has been investigated. Slurry conversion experiments show that the transition temperature below which FI is stable is located between 302 K-303 K (29 degrees C-30 degrees C). The polymorphs FI and FII have been characterised by infrared spectroscopy (IR), Raman spectroscopy, transmission powder X-ray diffraction (XRPD) and differential scanning calorimetry (DSC). The isobaric solid state heat capacities have been measured by DSC. The quantitative thermodynamic stability relationship has been determined in a comprehensive thermodynamic analysis of the calorimetric data. The solubility of both polymorphs has been determined in eight pure organic solvents over the temperature range 278 K-323 K by a gravimetric method. The mole fraction solubility of benzocaine decreases in the order: 1,4-dioxane, acetone, ethyl acetate, chloroform, acetonitrile, methanol, n-butanol and toluene. Comparison with the determined activity of solid benzocaine forms shows that negative deviation from Raoult's law ideality is found in dioxane, acetone and ethyl acetate solutions, and positive deviation in solutions of the other investigated solvents.
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| 5. |
- Crutzen, Jordan, et al.
(författare)
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Mesoscale clusters in multicomponent systems: the effect of solution preparation and pre-treatment on primary nucleation of a carbamazepine-saccharin cocrystal
- 2023
-
Ingår i: CrystEngComm. - : Royal Society of Chemistry. - 1466-8033. ; 25:28, s. 4048-4057
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Tidskriftsartikel (refereegranskat)abstract
- In this work, direct investigation of mesoscale clusters in solution using dynamic light scattering is combined with an indirect method based on the study of primary crystal nucleation and its dependence on the conditions of solution preparation and pre-treatment. In a novel approach we have studied how the nucleation induction time of a pharmaceutical cocrystal, a 1 : 1 saccharin-carbamazepine cocrystal, depends on different preparation and pre-treatment conditions, in particular whether solutions are prepared by dissolving the cocrystal solids or the two coformers separately. Nucleation is clearly affected by some pre-treatment conditions, with longer induction times obtained for a high pre-treatment temperature and when solutions are microfiltered after dissolution. The strongest effect was observed when comparing different starting materials, with solutions prepared using cocrystals leading to much shorter induction times than solutions based on the separate coformers. DLS shows that both types of solutions contain mesoscale clusters of the order of 100-300 nm in size, but that there are clear differences in the amount of scattering indicating a higher cluster concentration in the solutions based on cocrystal solids. The results suggest the possibility that mesoscale clusters can have a structural dimension, associated with slow kinetics, which can directly affect nucleation.
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| 6. |
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| 7. |
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| 8. |
- Diniz, Mariana O., et al.
(författare)
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New Solid Forms of Griseofulvin : A Solvate and a Relict Polymorph Related to Reported Solvates
- 2023
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 23:12, s. 8953-8961
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Tidskriftsartikel (refereegranskat)abstract
- This work presents two new solid forms, a polymorph and a solvate, of the antifungal active pharmaceutical ingredient griseofulvin (GSF). The novel forms were characterized by powder X-ray diffraction, differential scanning calorimetry, and thermogravimetric analysis, and their crystal structures were determined by single-crystal X-ray diffraction. The new polymorphic form (GSF Form VI) was obtained upon drying at room temperature the GSF-acetonitrile solvate. GSF Form VI is a relict structure related to reported solvates of GSF. Thermal stability studies show that Form VI is metastable and monotropically related to the stable GSF Form I. The new GSF-n-butyl acetate solvate was obtained by crystallization from an n-butyl acetate solution. The stoichiometry of the n-butyl acetate solvate is 1:0.5. The solvate loses the solvent from the crystal lattice at a temperature between 363.15 and 374.15 K.
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| 9. |
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| 10. |
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| 11. |
- Kakkar, Shubhangi, et al.
(författare)
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Characterization and Crystal Nucleation Kinetics of a New Metastable Polymorph of Piracetam in Alcoholic Solvents
- 2022
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 22:5, s. 2964-2973
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Tidskriftsartikel (refereegranskat)abstract
- A new polymorph of the drug active pharmaceutical ingredient piracetam (Form VI) has been discovered and characterized by X-ray powder diffraction (PXRD), solid-state Raman, attenuated total reflectance infrared spectroscopy, and differential scanning calorimetry. The PXRD diffractogram of Form VI shows a distinct peak at 24.2° (2θ) that distinguishes it from the previously known polymorphs and solvates. Form VI is metastable with respect to the previously known polymorphs Form II and Form III; in ethanol solution at 288 K, Form VI transforms into Form II within 15 min, while in isopropanol solution Form VI is kinetically stable for at least 6 h. A total of 1200 crystal nucleation induction time experiments of piracetam in ethanol and isopropanol solutions have been conducted, in sets of 40–80 repeat experiments carried out at different temperatures and solute concentrations. Each solution nucleated as a single polymorph, and each set of repeat experiments resulted in different proportions of Form II, Form III, and Form VI, with Form VI dominating at low nucleation temperatures and Form II at higher nucleation temperatures. The induction time data for Form VI at 288 K have been evaluated within the framework of the classical nucleation theory. At equal driving force, nucleation of Form VI is less obstructed in ethanol than in isopropanol, as captured by a lower interfacial energy and higher pre-exponential factor in ethanol. The proportion of Form VI obtained at a comparable driving force increases in the order ethanol < isopropanol.
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| 12. |
- Kakkar, Shubhangi, et al.
(författare)
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Crystal nucleation of salicylamide and a comparison with salicylic acid
- 2020
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Ingår i: CrystEngComm. - : Royal Society of Chemistry (RSC). - 1466-8033. ; 22:19, s. 3329-3339
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Tidskriftsartikel (refereegranskat)abstract
- Crystal nucleation of salicylamide has been investigated in four different solvents. The interfacial energy as determined within the classical nucleation theory is found to increase in the order acetonitrile < ethyl acetate < acetone < methanol. However, this is compensated for by a similar increase in the pre-exponential factor by which the overall influence of the solvent on the nucleation becomes weaker. In the evaluation, an approximate correction for solution activity coefficient ratios is used in the representation of the driving force. The nucleation results are compared with the nucleation of a similar compound: salicylic acid. It is found that the influence of the solvent has a similar trend for the two solutes while the nucleation of salicylic acid is somewhat easier. Possible explanations for this are discussed attempting to progress the rationalization of crystal nucleation of organic solutes in solution. It is found that the attachment factor in the different systems as predicted from physical properties correlates well with the experimentally determined pre-exponential factor.
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| 13. |
- Kipfer, Tristan, et al.
(författare)
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Upcycling of lithium cobalt oxide to LiNi1/3Mn1/3Co1/3O2
- 2024
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Ingår i: RSC Sustainability. - : Royal Society of Chemistry (RSC). - 2753-8125.
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Tidskriftsartikel (refereegranskat)abstract
- With the increasing demand for rechargeable lithium-ion batteries, arises an interest in the recycling processes for such devices. Possible methods include a range of processing conditions yielding different precursors which need to be integrated into upstream production. Here, we demonstrate a synthesis method that is compatible with the organic precursor obtained from citric acid-based leaching of lithium cobalt oxide (LCO) followed by acetone antisolvent crystallization. A lithium cobalt citrate (LCC) precipitate is retrieved and used directly as a precursor to synthesize LiNi1/3Mn1/3Co1/3O2 (NMC111) via a sol-gel method. The organic precursor is the only source of Co and provides a portion of the Li, while complementary metal salts supply the remaining metals in stoichiometric amounts. The role of metal salts (either acetates or sulfates of Ni, Mn and Li) on the quality and performance of the cathode materials is evaluated based on chemical composition and material purity. Electrochemical evaluation of the material produced from metal acetates showed comparable performance to that of a control material. The work connects previously studied methods of downstream leaching and antisolvent extraction with the upstream production of a desired cathode material through sol-gel synthesis. It is shown that our concept provides a path for avoiding primary and hazardous extraction of cobalt as the usage of the obtained citrate from acetone antisolvent crystallization of LCO can be applied as a precursor for NMC111 synthesis, with few steps and applying only non-toxic solvents.
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| 14. |
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| 15. |
- Ma, Chunyan, et al.
(författare)
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Antisolvent crystallization from deep eutectic solvent leachates of LiNi1/ 3Mn1/3Co1/3O2 for recycling and direct synthesis of battery cathodes
- 2023
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Ingår i: Resources, Conservation and Recycling. - : ELSEVIER. - 0921-3449 .- 1879-0658. ; 198
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Tidskriftsartikel (refereegranskat)abstract
- Deep eutectic solvents (DES) are a new class of environmentally friendly, safe, and inexpensive solvents with a remarkable ability to dissolve metal oxides, proposed as green alternatives to traditional acid leaching in the recycling of lithium-ion battery (LIB) cathode materials. In this work, a closed-loop process is targeted, where LiNi1/3Mn1/3Co1/3O2 (NMC) is leached by a DES (choline chloride and L-(+)-tartaric acid), and the metals are recovered by antisolvent crystallization. Five organic antisolvents have been evaluated, amongst which ethanol provides the highest metal recovery efficiency. The suitability of the solid precipitates as precursors for the sol -gel synthesis of new NMC, and the resulting cycling performance as battery cathodes, have been tested. The effect on the process of impurities Al and Cu from current collectors has been investigated. The impurities partially precipitate with the targeted metals, but the product impurity content can be significantly reduced through the selection of antisolvent, antisolvent-to-leachate ratio, crystallization residence time, and the rate of supersaturation generation in semi-batch mode. The resulting solids can be suitable for direct cathode resynthesis without the addition of a chelating agent, but impurities from current collectors decrease cycling performance. The results highlight the potential of combining DES leaching and antisolvent crystallization as a sustainable and efficient LIB cathode recycling method.
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| 16. |
- Ma, Yiqian, et al.
(författare)
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Application of Eutectic Freeze Crystallization in the Recycling of Li-Ion Batteries
- 2021
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Ingår i: Rare Metal Technology 2021. - Cham : Springer Nature. ; , s. 3-10
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Konferensbidrag (refereegranskat)abstract
- The widespread and increasing use of Li-ion batteries has led to an impending need for recycling solutions. Consequently, recycling of spent Li-ion batteries with energy-efficient, environmentally sustainable strategies has become a research hotspot. In this work, eutectic freeze crystallization (EFC), which requires less energy input than conventional evaporative crystallization (EC), has been investigated as a method for the recovery of Ni and Co sulfates from synthetic acidic strip solution in the recycling of NMC or NCA Li-ion batteries. Two binary sulfate systems have been studied. Batch EFC experiments have been conducted. It is shown that, with suitable control of supersaturation, ice and salt crystals can be recovered as separate phases below the eutectic temperatures. The work shows that EFC is a promising alternative to EC for the recovery of Ni and Co sulfates from spent Li-ion batteries.
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| 17. |
- Ma, Yiqian, et al.
(författare)
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Eutectic Freeze Crystallization for Recovery of Cobalt Sulfate in the Recycling of Li-Ion Batteries
- 2023
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Ingår i: Rare Metal Technology 2023. - Cham : Springer.
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Konferensbidrag (refereegranskat)abstract
- Crystallization of cobalt sulfate within a typical hydrometallurgical process for the recycling of Ni-Mn-Co oxide or Ni-Co-Al oxide Li-ion batteries has been investigated. The cobalt sulfate salt was obtained by eutectic freeze crystallization (EFC) from a synthetic acidic cobalt strip liquor after solvent extraction. The ternary phase diagram of CoSO4–H2SO4–H2O was first established by the mixed-solvent electrolyte (MSE) model to predict and reveal the changes in the system during the freezing process and to assess the conditions required for EFC. Batch EFC experiments were then conducted for the cobalt strip liquor, which contained a low concentration of impurities. It is shown that with suitable control of supersaturation, seeding, and stirring, pure ice and salt crystals can be recovered as separate phases at the eutectic temperatures, with the crystalline salts in the form of a heptahydrate. The crystallization process can be described using the ternary phase diagram, but with certain deviations. The deviations might be related to insufficient data at the low temperatures in the MSE model and acid entrapment in crystals during the crystallization process. Finally, the performance of the EFC process has been compared to that of an evaporative crystallization (EC) using the same strip liquor. It was found that the CoSO4·7H2O product obtained by EFC was of slightly higher quality considering purity and crystal shape compared to that from EC.
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| 18. |
- Ma, Yiqian, et al.
(författare)
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Eutectic freeze crystallization for recovery of NiSO4 and CoSO4 hydrates from sulfate solutions
- 2022
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Ingår i: Separation and Purification Technology. - : Elsevier BV. - 1383-5866 .- 1873-3794. ; 286
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Tidskriftsartikel (refereegranskat)abstract
- In this study, eutectic freeze crystallization (EFC) was investigated to recover NiSO4 and CoSO4 hydrates from aqueous and dilute sulfuric acid solutions of metal sulfates. Binary phase diagrams were established using a combination of thermodynamic modeling and experimental data. The mixed-solvent electrolyte (MSE) model was employed to model solid–liquid phase equilibria. The predicted binary phase diagrams from the model were in good agreement with the experimental results. Experimental eutectic temperatures and eutectic metal sulfate concentrations for the NiSO4-H2O and CoSO4-H2O systems are −3.3 °C and 20.8 wt% and −2.9 °C and 19.3 wt%, respectively. For NiSO4-H2SO4-H2O and CoSO4-H2SO4-H2O systems, the eutectic temperature and eutectic metal sulfate concentration decrease with increasing H2SO4 concentration. Batch experiments were performed to study the EFC of different sulfate solutions, including 25- wt% NiSO4 in H2O, 20- wt% NiSO4 in 0.5 mol/kg H2SO4, 25- wt% CoSO4 in H2O, and 20- wt% CoSO4 in 0.5 mol/kg H2SO4. The results show that controlling the supersaturation allows high-quality ice and salt crystals to be recovered as separate phases under eutectic conditions, with the crystalline salts in the form of heptahydrates. This study shows that EFC can be a promising alternative to evaporative crystallization for recovering NiSO4 and CoSO4 hydrates from sulfate solutions.
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| 19. |
- Ma, Yiqian, et al.
(författare)
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Phase diagrams of CoSO4-H2O and CoSO4-H2SO4-H2O systems for CoSO4·nH2O (n = 6,7) recovery by cooling and eutectic freeze crystallization
- 2024
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Ingår i: Hydrometallurgy. - : Elsevier BV. - 0304-386X .- 1879-1158. ; 227
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports the solid-liquid phase equilibria of the CoSO4-H2O and CoSO4-H2SO4-H2O systems at low temperatures. Binary and ternary phase diagrams, including the stable solid phases CoSO4·6H2O and CoSO4·7H2O were established using experimental data and thermodynamic modeling applying the mixed-solvent electrolyte (MSE) model. The results showed that the addition of H2SO4 shifts the eutectic temperature and concentration to lower values for cobalt sulfate and ice crystallization. The trends obtained from the experimental data and the modeling are consistent for the binary CoSO4-H2O system with good agreement, but the ternary CoSO4-H2SO4-H2O system shows some deviations. In general, the MSE model is shown to be reliable for inferring and establishing the phase diagram of the low-temperature system. The phase diagrams are helpful for designing the pathways of cooling crystallization and eutectic freeze crystallization and assessing the performance of the low-temperature crystallization process in the production of CoSO4 hydrates. In addition, some practical examples of cooling crystallization and eutectic freeze crystallization of CoSO4 solutions are provided.
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| 20. |
- Ma, Yiqian, et al.
(författare)
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Precipitation and crystallization used in the production of metal salts for Li-ion battery materials : A review
- 2020
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Ingår i: Metals. - : MDPI AG. - 2075-4701. ; 10:12
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Forskningsöversikt (refereegranskat)abstract
- Li-ion battery materials have been widely studied over the past decades. The metal salts that serve as starting materials for cathode and production, including Li2CO3, NiSO4, CoSO4 and MnSO4, are mainly produced using hydrometallurgical processes. In hydrometallurgy, aqueous precipitation and crystallization are important unit operations. Precipitation is mainly used in the processes of impurity removal, separation and preliminary production, while controlled crystallization can be very important to produce a pure product that separates well from the liquid solution. Precipitation and crystallization are often considered in the development of sustainable technologies, and there is still room for applying novel techniques. This review focuses on precipitation and crystallization applied to the production of metal salts for Li-ion battery materials. A number of novel and promising precipitation and crystallization methods, including eutectic freeze crystallization, antisolvent crystallization, and homogeneous precipitation are discussed. Finally, the application of precipitation and crystallization techniques in hydrometallurgical recycling processes for Li-ion batteries are reviewed.
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| 21. |
- Mangunda, Cledwyn, et al.
(författare)
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Recovery of High Purity Vanadium Salts from Bayer Liquor
- 2024
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Ingår i: Rare Metal Technology 2024. - : Springer Nature. ; , s. 87-96
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Konferensbidrag (refereegranskat)abstract
- Bauxite oresBauxite ore used in aluminium oxide production via the Bayer process contain trace elements (REEs, V, Li, Sc, Ga) currently not valorised. VanadiumVanadium and GalliumGallium dissolve during the Bayer process forming impurities in the Bayer liquorBayer liquor (sodium aluminate solution). VanadiumVanadium application ranges from steel to aircraft industries, and extraction involves ammonium treatment of strip liquor for vanadiumVanadium salt (AMV, V2O5) precipitation. Current crystallizationCrystallization techniques have drawbacks of generating voluminous, highly saline wastewater. This study investigated the use of antisolventAntisolvent (acetone) crystallizationCrystallization with synthetic solutions as an alternative to the crystallizationCrystallization and calcination step in the conventional production of high purityPurityvanadiumVanadium salts. The yieldYield, purityPurity, and product characteristics of the crystals for different final organic to aqueous (O/A) ratio at constant addition rate of antisolventAntisolvent at room temperature have been investigated. A batch time-dependent effect was observed with the best product quality, in terms of size and crystal habit (dominated by hexagonal laths), being attained when tb ≤ 2 h at an O/A ratio of 0.5. The early onset of acicular crystal formation and higher yieldsYield (≥ 97%), along with higher impurity incorporation into the solid phase, was observed at an O/A ratio of 0.75, and this was attributed to higher levels of supersaturationSupersaturation.
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| 22. |
- Moberg, Christina, et al.
(författare)
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De unga gör helt rätt när de stämmer staten : 1 620 forskare och lärare i forskarvärlden: Vi ställer oss bakom Auroras klimatkrav
- 2022
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Ingår i: Aftonbladet. - : Aftonbladet. ; :2022-12-07
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Vi, 1 620 forskare samt lärare vid universitet och högskolor, är eniga med de unga bakom Auroramålet: De drabbas och riskerar att drabbas allvarligt av klimatkrisen under sin livstid. De klimatåtgärder vi vidtar i närtid avgör deras framtid. Sverige måste ta ansvar och göra sin rättvisa andel av det globala klimatarbetet. I strid med Parisavtalet ökar utsläppen av växthusgaser i en takt som gör att 1,5-gradersmålet kan överskridas om några år. De globala effekterna blir allt mer synliga med ständiga temperaturrekord, smältande isar, havshöjning och extremväder som torka, förödande bränder och skyfall med enorma översvämningar, som i Pakistan nyligen. Försörjningen av befolkningen utsätts för allvarliga hot i många länder.Minskningen av den biologiska mångfalden är extrem. Klimatkrisen är enligt WHO det största hotet mot människors hälsa i hela världen och barn utgör en särskilt sårbar grupp. Med Sveriges nordliga läge sker uppvärmningen här dubbelt så fort som det globala genomsnittet. Det förskjuter utbredningsområden för växtlighet och sjukdomsbärande insekter och ökar förekomsten av extremväder såsom värmeböljor, skogsbränder och översvämningar samt av många olika sorters infektioner och allergier. När extremväder ökar, ökar även stressen och risken för mental ohälsa. Värmeböljor ökar risken för sjukdom och död hos sårbara grupper som äldre, små barn och personer med kroniska sjukdomar. De negativa effekterna på hälsan kommer att öka i takt med klimatkrisen och barn riskerar att drabbas av ackumulerade negativa hälsoeffekter under hela sina liv. Redan i dag är mer än hälften av unga mellan 12 och 18 år i Sverige ganska eller mycket oroliga för klimat och miljö. Detta är förståeligt när våra beslutsfattare inte gör vad som krävs.Den juridiska och moraliska grunden för arbetet mot klimatförändringarna är att varje land måste göra sin rättvisa andel av det globala klimatarbetet. Centralt i det internationella klimatramverket är att rika länder med höga historiska utsläpp, däribland Sverige, måste gå före resten av världen. Dessa länder måste också bidra till att finansiera klimatomställningen i länderna i det Globala Syd, som är minst ansvariga för klimatkrisen men drabbas hårdast. Denna rättviseprincip är tydlig i Parisavtalet och var en het diskussionsfråga under COP27 i Sharm el-Sheikh, men lyser med sin frånvaro i det svenska klimatarbetet. Sverige har satt mål för att minska sina utsläpp. Men de är helt otillräckliga: minskningstakten är för låg och målen tillåter samtidigt att åtgärder skjuts på framtiden. Dessutom exkluderas merparten av Sveriges utsläpp från de svenska nationella utsläppsmålen; bland annat utelämnas utsläpp som svensk konsumtion orsakar utanför Sveriges gränser, utsläpp från utrikes transporter och utsläpp från markanvändning och skogsbruk, exempelvis utsläpp från förbränning av biobränslen eller utsläpp från dikade våtmarker (Prop. 2016/17:146 s.25-28).Sverige saknar dessutom ett eget mål för att öka upptaget av växthusgaser genom utökat skydd och restaurering av ekosystem, något som krävs för att begränsa de värsta konsekvenserna av klimatkrisen (IPCC s.32). Trots dessa låga ambitioner misslyckas Sverige med att nå sina utsläppsmål, konstaterar både Klimatpolitiska rådet och Naturvårdsverket. En klimatpolitik i linje med Parisavtalet kräver både att alla typer av växthusgasutsläpp minskar samtidigt som – inte i stället för – upptaget av växthusgaser maximeras: i dag misslyckas Sverige på bägge fronter.Slutsatsen är tydlig. Sverige vidtar inte de åtgärder som krävs för att skydda barns och ungdomars rättigheter enligt Europakonventionen till skydd för de mänskliga rättigheterna. Detta medför allvarliga risker för liv och hälsa för unga generationer, människor i andra länder och särskilt utsatta grupper. Detta kan inte fortsätta. Därför ställer vi oss bakom Auroras krav att Sverige börjar göra sin rättvisa andel och omedelbart sätter igång ett omfattande och långtgående klimatarbete som vilar på vetenskaplig grund och sätter rättvisa i centrum.
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| 23. |
- Peters, Edward, Doktorand, 1985-, et al.
(författare)
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Effect of Antisolvent Type and Concentration on Morphology and Crystal Size of (NH4)3ScF6 Obtained by Antisolvent Crystallization
- 2022
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Ingår i: Rare Metal Technology 2022. - Cham : Springer Nature.
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Konferensbidrag (refereegranskat)abstract
- Scandium is a metal of value with increasing demand but limited supply. During the valorization of bauxite residue, scandium becomes concentrated in an NH4F strip liquor, from which it can be recovered as (NH4)3ScF6 by antisolvent crystallization. This study investigates the use of different antisolvents and their concentrations on the morphology and crystal size of the (NH4)3ScF6 crystals produced. The antisolvents include alcohols, ketones, and a sulfoxide. These were added all at once, either pure or diluted, to the aqueous solution to attain final concentration of 2, 4, or 8 mol/L total solution in separate experiments. Changes in the functional group and concentration of the antisolvents were observed to induce morphological and crystal size modifications of (NH4)3ScF6. The differences are likely due to the specific interactions of the antisolvent molecules with the atoms at the different faces of the crystals.
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| 24. |
- Peters, Edward, Doktorand, 1985-, et al.
(författare)
-
Impact of process parameters on product size and morphology in hydrometallurgical antisolvent crystallization
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The recovery of scandium from waste streams of mining and metallurgicaloperations presents an opportunity to balance supply and demand of thiscommodity. This study expands on the research focusing on the recovery ofscandium as (NH4)3ScF6 from strip liquors by antisolvent crystallization usingethanol as the antisolvent. The effect of process conditions includingcontrolling the rate of supersaturation generation, agitation mechanism,feeding point location with respect to local supersaturation, and seeding areassessed with emphasis on the final crystal size distributions (CSD) andmorphology. Controlling the supersaturation by reducing the ethanolconcentration coupled with controlled antisolvent addition at a low additionrate had the greatest effect on increasing the crystal sizes, although broaderCSDs were obtained. Morphological modifications, without polymorphictransformations, were also observed when one-pot addition of 60 or 70% v/vethanol was conducted, but not observed when the dilute antisolvents were fedat a controlled low addition rate.
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| 25. |
- Peters, Edward, Doktorand, 1985-, et al.
(författare)
-
Impact of process parameters on product size and morphology in hydrometallurgical antisolvent crystallization
- 2022
-
Ingår i: CrystEngComm. - : Royal Society of Chemistry (RSC). - 1466-8033. ; 24:15, s. 2851-2866
-
Tidskriftsartikel (refereegranskat)abstract
- The recovery of scandium from waste streams of mining and metallurgical operations presents an opportunity to balance supply and demand of this commodity. This study expands on the research focusing on the recovery of scandium as (NH4)3ScF6 from strip liquors by antisolvent crystallization using ethanol as the antisolvent. The effect of process conditions including reducing the rate of supersaturation generation, agitation mechanism, feeding point location with respect to local supersaturation, and seeding are assessed with emphasis on the final crystal size distributions (CSD) and morphology. Reducing the rate of supersaturation generation by reducing the ethanol concentration and by controlling the rate of antisolvent addition had the greatest effect on increasing the crystal sizes, although broader CSDs were obtained. Morphological modifications, without polymorphic transformations, were also observed when one-pot addition of 60 or 70% v/v ethanol was conducted, but not observed when the dilute antisolvents were fed at a controlled low addition rate.
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| 26. |
- Peters, Edward, Doktorand, 1985-, et al.
(författare)
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Recovery of alcohol after anti-solvent precipitation of (NH4)3ScF6 from NH4F strip liquors
- 2020
-
Ingår i: IMPC 2020 Congress Proceedings.
-
Konferensbidrag (refereegranskat)abstract
- Scandium can be recovered from waste streams of other metallurgical processes such as red mud from the Bayer process and titanium dioxide acid waste. This is accomplished by an integrated process comprising leaching using acidic media, solvent extraction using organic solvents and stripping of Sc from the organic phase using NH4F solutions. The precipitation of scandium as (NH4)3ScF6 from NH4F strip liquors has been demonstrated at lab-scale with recoveries and purities greater than 98% and 98.3%, respectively. It is desired to assess the possibility to recover the solvents for re-use in the process to improve its economy and environmental friendliness. Investigations have been conducted to recover alcohol by simple distillation from strip liquor-alcohol mixtures containing about 50 v/v% alcohol. The mixtures were obtained after anti-solvent precipitation of (NH4)3ScF6 using an alcohol to strip liquor volumetric ratio of 1:1. The starting strip liquor contained about 2000 mg/L scandium in 3 mol/L NH4F solution. In the recovery of methanol, the first distillate product collected had a purity of about 87 v/v% and this decreased slightly with time over 2 hours. The methanol distillate collected in the first 30 minutes with a purity of ca. 85 v/v% was re-used in anti-solvent crystallization of (NH4)3ScF6 from the initial strip liquor, and the scandium recovery attained was about 98.6 w/w%, almost similar to that of 99.2 w/w% obtained using 100 v/v% methanol. For ethanol recovery, the first distillate product collected was approx. 84 v/v% pure and the distillate collected in the first 30 minutes with a purity of about 75 v/v% achieved a scandium recovery of about 97.2 w/w% in comparison to 98.5 w/w% obtained using 100 v/v% ethanol during anti-solvent crystallization.
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| 27. |
- Peters, Edward, Doktorand, 1985-
(författare)
-
Recovery of Scandium using Antisolvent Crystallization in the Valorization of Scandium-containing Waste Streams
- 2022
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Scandium is widely dispersed in the earth’s crust and is rarely concentrated in ores, and a viable option to guarantee a secure supply of scandium is to recover the metal from waste streams of other mining and metallurgical facilities. The valorization of such streams to recover metals of value is a prerequisite to alleviate the global shortages of scandium and other rare earth elements. The purpose of this research is to exploit crystallization techniques amongst other unit operations in the valorization of scandium from waste streams such as bauxite residue and titanium dioxide acid waste. The entire process is envisaged as consisting of unit operations such as leaching of the bauxite residue, solvent extraction of the pregnant leach liquors and stripping, crystallization of a scandium salt from the strip liquors, calcination and metallothermic reduction.Synthetic and real strip liquors with ammonium fluoride matrix were used in this study. The real strip liquors were obtained by leaching and solvent extraction of typical industrial waste streams and stripping the metals from the organic phase to the aqueous phase using NH4F solution. Antisolvent crystallization using alcohol solvents proved to be a more effective method for recovering scandium as ammonium scandium hexafluoride, (NH4)3ScF6, from such strip liquors, since a higher percentage recovery of scandium was obtained in comparison to cooling crystallization. Therefore, the phase equilibria of ammonium scandium fluorides has been investigated in pure NH4F solutions and in 3 mol/L NH4F-alcohol mixtures for methanol, ethanol, 2-propanol and 1,3-propane-diol in the concentration range 0.5 – 9 mol/L. Thesolubility of ammonium metal fluorides of the impurity metals such as Ti, Zr, Al and Fe was also determined in 3 mol/L NH4F-ethanol mixtures. (NH4)2TiF6 was observed to have exceptionally high solubility in these solutions possibly due to the prevalence of the titanyl ion in solution. The other ammonium metal fluorides investigated exhibited comparable or considerably lower solubilities than (NH4)3ScF6. Antisolvent crystallization using strip liquors with varying scandium to impurity ratios revealed that the uptake of impurity metals into the final solid product occurs in proportions that reflect their relative abundances in the strip liquor. However, the uptake of Ti into the solid product is minimal since Ti remains solubilized.The impact of processing conditions on the crystal size distribution, morphology and purity of (NH4)3ScF6 in a batch antisolvent crystallization process was investigated. These include the control of supersaturation, antisolvent feeding mode, agitation mechanism, external seeding, and two-stage internal seeding. The control of supersaturation by reducing the antisolvent concentration and adding the dilute antisolvent at a sufficiently low addition rate had the greatest effect on increasing the crystal sizes, although it caused significant broadening of the product CSD. The use of an overhead pitched blade impeller also resulted in remarkable increase in crystal sizes compared to a magnetic stirrer, possibly due to reduced crystal attrition and more effective mixing, which reduces the local supersaturation generated, thereby suppressing nucleation. The addition of dilute ethanol (70 and 60% v/v), when added all at once, caused morphological modifications of (NH4)3ScF6 from isodimensional prismatic crystals to elongated crystals, but this was not observed under controlled addition of the dilute ethanol. This clearly shows the significance of operating conditions in manipulating the product quality obtained. The technical feasibility of recovering the antisolvent for reuse has also been demonstrated.
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| 28. |
- Peters, Edward, Doktorand, 1985-, et al.
(författare)
-
Solubility of ammonium metal fluorides in aqueous ethanol mixtures : implications for scandium recovery by antisolvent crystallization
- 2023
-
Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 13:2, s. 1288-1294
-
Tidskriftsartikel (refereegranskat)abstract
- The recovery of scandium from waste streams of other mining and metallurgical processing industries is gaining research interest due to the scarcity of scandium-containing ores. Hydrometallurgical techniques such as leaching, solvent extraction and crystallization amongst others have been successfully applied to recover scandium salts from such waste streams. Scandium can be recovered as (NH4)(3)ScF6 by antisolvent crystallization from NH4F strip liquors obtained after solvent extraction. The coextraction of metal impurities such as Fe, Al, Zr and Ti causes contamination of the final solid product. The extent of coprecipitation of ammonium metal fluorides depends on their initial concentration in the strip liquor and their solubility in the NH4F-antisolvent mixtures. Here, the solubility of ammonium metal fluorides of Sc, Zr, Fe, Al and Ti is reported separately in 3 mol L-1 NH4F-ethanol mixtures at 25 degrees C as well as in a system containing all five solid phases. The solubility of (NH4)(3)ZrF7 is slightly higher than that of (NH4)(3)ScF6, while the solubilities of (NH4)(3)FeF6 and (NH4)(3)AlF6 are significantly lower in comparison to (NH4)(3)ScF6. The solubility of (NH4)(2)TiF6 is 1-2 orders of magnitude higher than those of other ammonium metal fluorides. When a mixture of ammonium metal fluoride salts is dissolved in the same 3 mol L-1 NH4F-ethanol mixture as for the individual salts, the resultant solubility of the ammonium metal fluorides of Sc, Zr and Fe decreases significantly, while the resultant solubility of ammonium aluminum hexafluoride increases. This is likely due to changes in solution speciation with increased NH4F concentration and ionic strength.
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| 29. |
- Peters, Edward, Doktorand, 1985-, et al.
(författare)
-
Solubility of Ammonium Metal Fluorides of Sc, Fe, Al, Zr and Ti in Aqueous NH4F-Ethanol Mixtures
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The recovery of scandium from waste streams of other mining and metallurgical processing industries is gaining research interest due to the scarcity of scandium-containing ores. Hydrometallurgical techniques such as leaching, solvent extraction and crystallization amongst others have been successfully applied to recover scandium salts from such waste streams. Scandium can be recovered as (NH4)3ScF6 by antisolvent crystallization from NH4F strip liquors obtained after solvent extraction. The coextraction of metal impurities such as Fe, Al, Zr and Ti causes contamination of the final solid product. The extent of coprecipitation of ammonium metal fluorides depends on their initial concentration in the strip liquor and their solubility in the NH4F-antisolvent mixtures. Here, the solubility of ammonium metal fluorides of Sc, Zr, Fe, Al and Ti are reported separately in 3 mol/L NH4F-ethanol mixtures at 25 oC as well as in a system containing all five solid phases. The solubility of (NH4)3ZrF7 is observed to be slightly higher than that of (NH4)3ScF6, while the solubilities of (NH4)3FeF6 and (NH4)3AlF6 are observed to be significantly lower in comparison to (NH4)3ScF6. The solubility of (NH4)2TiF6 is observed to be 1 – 2 orders of magnitude higher than those of other ammonium metal fluorides. The presence of all metal ions in solution is observed to decrease the solubility of the ammonium metal fluorides of Sc, Zr and Fe significantly, and increase the solubility of ammonium aluminum hexafluoride, possibly due to changes in solution speciation with increase in ionic strength and NH4F concentration.
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| 30. |
- Sanku, Meher, et al.
(författare)
-
Extraction Chromatography for Separation of Rare Earth Elements
- 2021
-
Ingår i: Rare Metal Technology 2021. - Cham : Springer Nature. - 9783030654887 ; , s. 155-161
-
Konferensbidrag (refereegranskat)abstract
- Developing efficient and viable processes for separation of critical metals is essential to meet the increasing demand. Rare earth elements (REEs) are identified by the EU as critical resources, and moreover, they are difficult to separate due to their similar properties. Extraction chromatography is a powerful method suitable for difficult, high-purity separations, which could form part of a separation process for recovery of REEs from various sources. In the present work, separation of REEs from synthetic apatite leach solutions is investigated using physically immobilized extractants. By means of reverse-phase columns, reversibly functionalized by acidic organophosphorus compounds, the metals are separated by elution with nitric acid solution.
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| 31. |
- Sanku, Meher, et al.
(författare)
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Impregnation of Preparative High-Performance Solid Phase Extraction Chromatography Columns by Organophosphorus Acid Compounds
- 2022
-
Ingår i: Journal of Chromatography A. - : Elsevier BV. - 0021-9673 .- 1873-3778. ; 1676, s. 463278-463278
-
Tidskriftsartikel (refereegranskat)abstract
- The flexible and reversible preparation of columns for use in high-performance solid phase extraction chromatography by physisorption of organophosphorus acid extractants has been investigated in detail. Two extractants have been evaluated, bis (2-ethyl-1-hexyl) phosphoric acid (HDEHP) and 2-ethyl-1-hexyl (2-ethyl-1-hexyl) phosphonic acid (HEHEHP), but the developed procedure should be broadly applicable to other extractants. The liquid-liquid solubility of the extractants in feed solvents consisting of aqueous ethanol solutions of varying composition has been determined. The total amount of adsorbed extractant has been quantified by complete desorption and elution with ethanol followed by acid-base titrimetry. Column impregnation with feed solutions of varying concentration in the undersaturated region has been systematically evaluated, and the influence of a subsequent water wash step has been explored. It is shown that to achieve a robust and reproducible physisorption, the adsorbed amount of extractant should be determined after the wash step, and care must be taken when using indirect methods of measurement. Equilibrium Langmuir-type adsorption isotherms as a function of the extractant concentration in the feed solution have been determined. Adsorption of HEHEHP is higher than HDEHP for equal feed compositions, but the solubility of HEHEHP is lower, resulting in approximately identical maximum coverage levels. The ability of the resulting columns to separate rare earth elements have been verified for a mixture of eight metals using a combined isocratic and gradient elution of nitric acid.
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| 32. |
- Seda Demirel, Hilal, et al.
(författare)
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Antisolvent Crystallization of Battery Grade Nickel Sulphate Hydrate in the Processing of Lateritic Ores
- 2022
-
Ingår i: Separation and Purification Technology. - : Elsevier BV. - 1383-5866 .- 1873-3794. ; 286
-
Tidskriftsartikel (refereegranskat)abstract
- Lithium-ion batteries are a crucial part in the rapid, on-going electrification of the global vehicle fleet, which is essential in enabling a transition to a society based on renewable energy. By combining metals including lithium, nickel, cobalt, and manganese in different proportions, cathode active materials with different properties can be obtained. Nickel sulphate hexahydrate, which is of great importance to the battery industry, can be produced by hydrometallurgical processing of lateritic and sulphide ores. Antisolvent crystallization is examined as an alternative to conventional crystallization methods for the production of high-grade nickel sulphate hexahydrate in the processing of lateritic nickel ores from Turkey. The ore has been leached under atmospheric pressure followed by purification by ion exchange resulting in a solution enriched with respect to nickel together with a range of impurity metals from which NiSO4·6H2O can be obtained by antisolvent crystallization. Separate antisolvent crystallization experiments have been carried out for nickel, cobalt and iron sulphate systems, which are the main metals present in the solution, and solubility data has been determined for key conditions. Acetone and isopropanol have been evaluated as antisolvents. Antisolvent crystallization experiments have also been carried out using synthetic solutions and the effect of addition rate of antisolvent, addition of diluted antisolvent and seeding on the purity of the crystals has been investigated. Acetone gives the best product quality in terms of purity and shape. Seeding and a slow rate of addition of dilute antisolvent gives the highest purity of the NiSO4·6H2O crystals. Under optimised conditions, crystals containing 22.3% Ni with a purity of 99.8% by mass have been obtained with a crystallization yield of 63.5%.
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| 33. |
- Soto, Rodrigo, et al.
(författare)
-
Solubility and thermodynamic analysis of famotidine polymorphs in pure solvents
- 2021
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Ingår i: International Journal of Pharmaceutics. - : Elsevier BV. - 0378-5173 .- 1873-3476. ; 607
-
Tidskriftsartikel (refereegranskat)abstract
- The present study investigates the solubility of famotidine polymorphs forms A and B between 298.15 K and 348.15 K in a range of pure solvents: water, methanol, ethanol, isopropanol and acetonitrile. Empirical and semi empirical models have been fitted to solubility data determined experimentally by a gravimetric method. The solid phases have been characterized by FTIR and Raman spectroscopy, SEM and PXRD. In addition, heat capacities and melting data determined by DSC have been used to estimate the fusion thermodynamics and the activity of the solid phases as a function of temperature. The relationship between the famotidine polymorphs is monotropic, with form A being the stable polymorph. For both polymorphs, in terms of mass ratio, the solubility in the studied solvents decreases in the order methanol > water > ethanol > acetonitrile > isopropanol. The activity coefficient at saturation in all the solutions exceeds unity, showing a positive deviation with respect to ideality, which translates into solubilities significantly lower than the ideal values. Among the alcohols, a consistent correlation is observed between the polarity and the order of solubility.The Hildebrand solubility parameter is also well correlated with the order of solubilities in the studied solvents, with a higher solubility in more polar solvents, revealing the importance of the hydrogen bonding of the sulfamoyl group oxygens.
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| 34. |
- Soto, Rodrigo, et al.
(författare)
-
Solubility and thermodynamic analysis of ketoprofen in organic solvents
- 2020
-
Ingår i: International Journal of Pharmaceutics. - : Elsevier BV. - 0378-5173 .- 1873-3476. ; 588
-
Tidskriftsartikel (refereegranskat)abstract
- The solubility of the racemic solid phase of ketoprofen (KTP) in methanol, ethanol, isopropanol, butanol, acetonitrile, ethyl acetate, 1,4-dioxane and toluene has been determined between 273 and 303 K by a gravimetric method. FTIR and Raman spectroscopy, SEM and PXRD, have been used to characterise the solid phase. The melting data and heat capacity of solid and melt have been determined by DSC, and used to estimate fusion thermodynamics and the activity of the solid phase as functions of temperature. Empirical and semi-empirical models have been fitted to experimental solubility data. The solution activity coefficients reveal positive deviation from ideality in all solvents except for in dioxane, and very close to ideality in methanol. The solubility is fairly high in the alcohols but decrease with increasing hydrocarbon chain. Generally and due to the presence of the carboxylic acid group, KTP is more readily dissolved in polar protic solvents, followed in order by polar aprotic and non-polar solvents. However, the highest solubility is found in dioxane, classified as a non-polar solvent, but notably though the molecule having two strong hydrogen bond accepting functionalities, and no hydrogen bond donation capability.
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| 35. |
- Svärd, Michael, Docent, 1976-, et al.
(författare)
-
Addressing the Reuse of Deep Eutectic Solvents in Li‐ion Battery Recycling : Insights Into Dissolution Mechanism, Metal Recovery, Regeneration and Decomposition
- 2024
-
Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X.
-
Tidskriftsartikel (refereegranskat)abstract
- Deep eutectic solvents (DESs) have garnered attention in Li-ion battery (LIB) recycling due to their declared eco-friendly attributes and adjustable metal dissolution selectivity, offering a promising avenue for recycling processes. However, DESs currently lack competitiveness compared to mineral acids, commonly used in industrial-scale LIB recycling. Current research primarily focuses on optimizing DES formulation and experimental conditions to maximize metal dissolution yields in standalone leaching experiments. While achieving yields comparable to traditional leaching systems is important, extensive DES reuse is vital for overall recycling feasibility. To achieve this, evaluating the metal dissolution mechanism can assist in estimating DES consumption rates and assessing process makeup stream costs. The selection of appropriate metal recovery and DES regeneration strategies is essential to enable subsequent reuse over multiple cycles. Finally, decomposition of DES components should be avoided throughout the designed recycling process, as by-products can impact leaching efficiency and compromise the safety and environmental friendliness of DES. In this review, these aspects are emphasized with the aim of directing research efforts away from simply pursuing the maximization of metal dissolution efficiency, towards a broader view focusing on the application of DES beyond the laboratory scale.
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| 36. |
- Svärd, Michael, Docent, 1976-, et al.
(författare)
-
Calorimetric Determination of Cocrystal Thermodynamic Stability : Sulfamethazine-Salicylic Acid Case Study
- 2020
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 20:7, s. 4243-4251
-
Tidskriftsartikel (refereegranskat)abstract
- This work demonstrates how the thermodynamics of cocrystal formation from the pure, solid coformers can be directly determined from experimentally obtained calorimetric data, without involving solubility data or approximations of ideal solution. For the 1:1 cocrystal between the drug API sulfamethazine and salicylic acid, the melting temperatures and associated enthalpies of fusion have been determined for the coformers in their respective pure solid state and as an equimolar physical mixture and for the cocrystal, using differential scanning calorimetry. Heat capacities have been determined for the respective solid forms and their supercooled melts. The Gibbs energy for cocrystal formation and the enthalpic and entropic components have been determined as functions of temperature through a thermodynamic cycle. The Gibbs energy, enthalpy, and entropy of mixing have been estimated from the thermodynamic functions for cocrystal formation and fusion of the solid phases. The results show that the Gibbs energy for cocrystal formation is negative, i.e. the cocrystal is the stable solid phase in relation to a 1:1 mixture of the coformers throughout the temperature interval from room temperature to the cocrystal melting point, and becomes increasingly negative with increasing temperature. Cocrystal formation is an endothermic process, driven by the favorable entropy increase, and is accompanied by a 6% increase in molecular volume. At room temperature, liquid mixing of coformers is found to be weakly exothermic. The results qualitatively align with a previously reported analysis based on solubility data.
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| 37. |
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| 38. |
- Svärd, Michael, Dr, Docent, 1976-, et al.
(författare)
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Estimating the crystallization driving force
- 2017
-
Ingår i: <em>Proceedings of the 20<sup>th</sup> international symposium on industrial crystallization, Dublin, Ireland </em>(2017).
-
Konferensbidrag (refereegranskat)
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| 39. |
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| 40. |
- Svärd, Michael, Docent, 1976-
(författare)
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Mesoscale clusters of organic solutes in solution and their role in crystal nucleation
- 2022
-
Ingår i: CrystEngComm. - : Royal Society of Chemistry (RSC). - 1466-8033. ; 24:29, s. 5182-5193
-
Tidskriftsartikel (refereegranskat)abstract
- It is becoming evident that primary nucleation of crystals of organic molecules from solution is often anything but ‘classical’ in its complexity. It is also becoming increasingly clear that mesoscopic clusters of molecules are at least partly involved in the phenomenon. On-going advances are rapidly enabling these clusters to be investigated with ever more accuracy. However, despite numerous recent studies, fundamental knowledge of the properties, thermodynamics and kinetics of these clusters, and of their role in nucleation, is still limited.
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| 41. |
- Svärd, Michael, Docent, 1976-, et al.
(författare)
-
Solid and Solution State Thermodynamics of Polymorphs of Butamben (Butyl 4-Aminobenzoate) in Pure Organic Solvents
- 2019
-
Ingår i: Journal of Pharmaceutical Sciences. - : Elsevier. - 0022-3549 .- 1520-6017. ; 108:7, s. 2377-2382
-
Tidskriftsartikel (refereegranskat)abstract
- The solubility of butamben has been measured gravimetrically in pure methanol, 1-propanol, 2-propanol, 1-butanol, and toluene over the temperature range 268-298 K. Polymorph transition and melting temperatures, associated enthalpy changes, and the heat capacity of the solid forms and the supercooled melt have been measured by differential scanning calorimetry. Based on extrapolated calorimetric data, the Gibbs energy, enthalpy and entropy of fusion, and the activity of solid butamben (the ideal solubility) have been calculated from below ambient temperature up to the melting point. Activity coefficients of butamben at equilibrium in the different solvents have been estimated from solubility data and the activity of the solid, revealing that all investigated systems exhibit positive deviation from Raoult's law. Solubility data are well correlated by a semiempirical regression model. On a mass basis, the solubility is clearly higher in methanol than in the other solvents, but mole fraction solubilities are very similar across all 5 solvents. The 2 known polymorphs are enantiotropically related, and the transition point is located at 283 K. Polymorph interconversions occur within 0.3 K of the transition point even in the solid state, and the 2 forms exhibit strong similarities in investigated properties.
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| 42. |
- Svärd, Michael, Dr, Docent, 1976-, et al.
(författare)
-
Synthesis, crystallisation and thermodynamics of two polymorphs of a new derivative of meglumine : 1-(2,2,3-trimethyl-1,3-oxazolidin-5-yl)-butane-1,2,3,4-tetrol
- 2018
-
Ingår i: CrystEngComm. - : ROYAL SOC CHEMISTRY. - 1466-8033. ; 20:1, s. 88-95
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Tidskriftsartikel (refereegranskat)abstract
- A new compound, 1-(2,2,3-trimethyl-1,3-oxazolidin-5-yl)-butane-1,2,3,4-tetrol, has been discovered, described, and its crystal polymorphism investigated. The crystal structures of two polymorphs have been solved with single-crystal X-ray diffraction. The molecule is chiral with four stereo centers, and both polymorphs crystallise in the non-centrosymmetric orthorhombic, chiral P2(1)2(1)2(1) space group, with one molecule in the asymmetric unit. In both structures the molecules are arranged three dimensionally in an interlocked manner, stabilized by strong O-H center dot center dot center dot O and weaker C-H center dot center dot center dot O and pi center dot center dot center dot pi interactions. The polymorphs have been characterized by X-ray powder diffraction (XRPD) and infrared spectroscopy (IR). The thermodynamic stability relationship between the polymorphs from 280 K up to the melting points has been quantitatively determined by differential scanning calorimetry (DSC), through measurement of melting points, heats of fusion, and heat capacities of the solid phases and the supercooled melt. It is established that the relationship is most likely monotropic, with one polymorph (FI) stable throughout the entire evaluated temperature range. The stability relationship at room temperature has been confirmed by a slurry conversion experiment.
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| 43. |
- Zeng, Lai, et al.
(författare)
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Solubility of Two Polymorphs of Tolbutamide in n-Propanol : Comparison of Methods
- 2020
-
Ingår i: Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0022-3549 .- 1520-6017. ; 109:10, s. 3021-3026
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Tidskriftsartikel (refereegranskat)abstract
- The solid-liquid solubility of two polymorphs of the title compound has been measured in n-propanol over the temperature range (278 K-303 K) by an isothermal, gravimetric method and a low heating rate polythermal method. Due to marked differences in the settling behavior of crystals of the two polymorphs in the investigated solvent, it is found that the low heating rate polythermal method gives the overall best performance for this particular system. Systematic slurry conversion experiments show that FII is the stable polymorph over the investigated temperature range (268 K-308 K). Solubility data for both polymorphs is well correlated, and has been extrapolated to the melting point, by a previously proposed semi-empirical regression model based on solid-phase calorimetric data. The system exhibits a marked positive deviation from Raoult's law, with solute activity coefficients at equilibrium decreasing with increasing temperature.
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