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Straszko, J.; Olszak-Humienik, M.; Możejko, J.

doi:10.1023/a:1010186628054

Cited by 25 publications

(10 citation statements)

References 1 publication

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“…25–30 In a typical procedure, about 1 g of solid metal sulfate polyhydrate was stirred and heated under an argon flow exiting through an external cold trap. Water evolution was monitored and typically ceased after a few minutes at the maximal temperature of: Fe, 140 °C; Zn, 150 °C; Cu, 170 °C; Co, 215 °C, and; Ni, 225 °C.…”

Section: Methodsmentioning

confidence: 99%

Spin-Polarization-Induced Preedge Transitions in the Sulfur K-Edge XAS Spectra of Open-Shell Transition-Metal Sulfates: Spectroscopic Validation of σ-Bond Electron Transfer

et al. 2017

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Sulfur K-edge XAS spectra of the monodentate sulfate complexes [MII(itao)(SO4)(H2O)0,1] and [Cu(Me6tren)(SO4)] exhibit well-defined pre-edge transitions at 2479.4 eV, 2479.9 eV, 2478.4 eV, and 2477.7 eV, respectively (M = Co, Ni, Cu), despite having no direct metal-sulfur bond, while the XAS pre-edge of [Zn(itao)(SO4)] is featureless. The sulfur K-edge XAS of [Cu(itao)(SO4)] but not of [Cu(Me6tren)(SO4)] uniquely exhibits a weak transition at 2472.1 eV, an extraordinary 8.7 eV below the first inflection of the rising K-edge. Pre-edge transitions also appear in the sulfur K-edge XAS of crystalline [MII(SO4)(H2O)] (M = Fe, Co, Ni, Cu, but not Zn) and in sulfates of higher-valent early transition metals. Ground state density functional theory (DFT) and time-dependent DFT (TDDFT) calculations show that charge transfer from coordinated sulfate to paramagnetic late transition metals produces spin polarization that differentially mixes the spin-up (α) and spin-down (β) spin-orbitals of the sulfate ligand, inducing negative spin density at sulfate sulfur. Ground state DFT calculations show that sulfur 3p character then mixes into metal 4s and 4p valence orbitals and various combinations of ligand anti-bonding orbitals, producing measureable sulfur XAS transitions. TDDFT calculations confirm the presence of XAS pre-edge features 0.5 to 2 eV below the sulfur rising K-edge energy. The 2472.1 eV feature arises when orbitals at lower energy than the frontier occupied orbitals with S 3p character mix with the Cu(II) electron hole. Transmission of spin polarization and thus of radical character through several bonds between the S and the electron hole provides a new mechanism for the counter-intuitive appearance of pre-edge transitions in the XAS spectra of transition metal oxoanion ligands in the absence of any direct metal-absorber bond. The 2472.1 eV transition is evidence for further radicalization from Cu(II), which extends across an H-bond bridge between sulfate and the itao ligand and involves orbitals at energies below the frontier set. This electronic structure feature provides direct spectroscopic confirmation of the through-bond electron transfer mechanism of redox-active metalloproteins.

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Section: Methodsmentioning

confidence: 99%

Spin-Polarization-Induced Preedge Transitions in the Sulfur K-Edge XAS Spectra of Open-Shell Transition-Metal Sulfates: Spectroscopic Validation of σ-Bond Electron Transfer

et al. 2017

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“…The statistical parameters; correlation coefficient r and Snedecor's variable F were calculated to aid the selection of the g(α) function best describing the experimental results [34]. The values of the kinetic and statistical parameters for all analysed models are listed in table 1.…”

Section: Thermal Characteristicsmentioning

confidence: 99%

Dielectric and thermal behaviour of holmium tartrate trihydrate crystals

Want

Ahmad

Kotru

2007

Cryst. Res. Technol.

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Measurements on dielectric constant of holmium tartrate trihydrate crystals at frequencies of the applied a.c. in the range 1 kHz to 1 MHz and at temperature in the range 30°C to 330°C are reported. The dielectric constant ε' increases with temperature at all frequencies, attains a peak near 250°C, and then decreases as the temperature goes beyond 250°C. The anomalous dielectric behaviour at near about 250°C is attributed to be as a result of crystallographic/polymorphic phase transition brought about in the material. The results on the dielectric behaviour of the material are supplemented by results of thermal analysis viz., TG and DTA. Thermogravimetric and differential thermal analytic techniques have been used to study thermal behaviour of the material. It is shown that the material is thermally stable up to 220°C beyond which it decomposes through three stages till the formation of holmium oxide at 1200°C. The non-isothermal kinetic parameters e.g., activation energy and the frequency factor have been evaluated for first two stages of thermal decomposition by using the integral method of Coats and Redfern.

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“…Thermal decompositions of the Ni, Co, and REE sulfates have been studied extensively [31,[33][34][35][36][37][38]. Solubility data of different REE, Ni, and Co sulfate hydrates and stability constants for the formation of different REE, Ni, and Co sulfate complexes are available in the literature [39][40][41].…”

Section: Electronic Supplementary Materialsmentioning

confidence: 99%

“…The residence time was varied from 1 to 3 h. This roasting process allowed the Ni and Co sulfate solid phases to decompose into their oxide forms while the REE remained in their sulfate forms. The temperature was selected based on available literature data on the thermal decomposition temperature range of the sulfates of REEs, nickel and cobalt [31,[33][34][35][36][37][38]45].…”

Section: Sulfation and Selective Roastingmentioning

confidence: 99%

“…The endothermic peak located at 586°C results from the decomposition of the nickel, cobalt and other minor element sulfates. The decompositions have been reported to occur at temperatures of 810 and 916°C for nickel sulfate and cobalt sulfate, respectively [35,37,48,49]. The thermal decomposition of nickel sulfate into nickel oxide is designated by the massive weight loss located in the center of the graph by considering the high mass percentage of nickel with respect to the rest of the elements.…”

Section: Materials Characterizationmentioning

confidence: 99%

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Recoveries of Valuable Metals from Spent Nickel Metal Hydride Vehicle Batteries via Sulfation, Selective Roasting, and Water Leaching

Korkmaz

Alemrajabi

Rasmuson

et al. 2018

J. Sustain. Metall.

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The recoveries of rare earth elements (REEs), nickel, and cobalt from hybrid electric vehicle batteries by sulfation, selective roasting, and water leaching have been studied. The cathode and anode materials of a Panasonic Prismatic Module nickel metal hydride (NiMH) battery were used in the study. The optimal conditions for each step of the process were determined by performing lab-scale experiments. It was found that 8 mol/L of sulfuric acid was sufficient for the sulfation with a solid-to-liquid ratio of 1/5. The optimal roasting conditions was determined to be 850°C for 2 h. Under optimal conditions, 96% of the REEs could be obtained in the aqueous phase with negligible contamination of Ni and Co. The Ni and Co remained in solid phase as oxides together with traces of aluminum, zinc, and iron oxides. This method provides a way for the separation of the REEs from nickel, cobalt, and other elements present in the NiMH battery, into a leachate suitable for further processing.

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Untitled

Cited by 25 publications

References 1 publication

Spin-Polarization-Induced Preedge Transitions in the Sulfur K-Edge XAS Spectra of Open-Shell Transition-Metal Sulfates: Spectroscopic Validation of σ-Bond Electron Transfer

Spin-Polarization-Induced Preedge Transitions in the Sulfur K-Edge XAS Spectra of Open-Shell Transition-Metal Sulfates: Spectroscopic Validation of σ-Bond Electron Transfer

Dielectric and thermal behaviour of holmium tartrate trihydrate crystals

Recoveries of Valuable Metals from Spent Nickel Metal Hydride Vehicle Batteries via Sulfation, Selective Roasting, and Water Leaching

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