Search results for " Crystal"
showing 10 items of 3073 documents
ION EXCHANGE MEMBRANE CRYSTALLIZER FOR MAGNESIUM RECOVERY FROM SEAWATER AND INDUSTRIAL BRINE
2020
The treatment and valorisation of waste brines deriving from industrial processes raised in the last years a strong interest in order to promote the whole process sustainability both in terms of minimisation of environmental impacts and raw materials recovery within a circular economy approach. With this respect, magnesium recovery from brines can be an interesting and practical example. In this work, a novel ion exchange membrane crystallizer (CrIEM1) is presented. In a CrIEM reactor, the presence of an Anion Exchange Membrane, separating a brine and an alkaline solutions, allows the passage of hydroxyl ions from the alkaline to the brine compartment, where crystallization of magnesium hyd…
An Ion Exchange Membrane Crystallisation reactor for Magnesium recovery from brines
2015
CrIEM technology is a novel ion exchange application that allows reactive crystallization for separation of valuable species (e.g. Mg from brines) with a large flexibility in the choice of reactants.
Heads or Tails? Sandwich-Type Metallocomplexes of Hexakis(2,3-di-O-methyl)-α-cyclodextrin
2020
Native and synthetically modified cyclodextrins (CDs) are useful building blocks in construction of large coordination complexes and porous materials with various applications. Sandwich-type complexes (STCs) are one of the important groups in this area. Usually, coordination of secondary hydroxyls or the “head” portal of native CD molecules to a notional multinuclear ring of metal cations leads to formation of head-to-head STCs. Our study introduces a new CD-ligand, hexakis(2,3-di-O-methyl)-α-cyclodextrin, which enables formation of intriguing head-to-head, but also novel tail-to-tail STCs. Homometallic silver-based head-to-head STCs, AgPF6-STC and AgClO4-STC, were obtained by coordination …
Synthesis and characterization of ferrocene-based Schiff base and ferrocenecarboxaldehyde oxime and their adsorptive removal of methyl blue from aque…
2018
Abstract The ferrocene-based Schiff base 3 was synthetized by reaction of ferrocenecarboxaldehyde 1 with 4-aminoantipyrine 2. However, the reaction of 1 with hydroxylamine affords ferrocenecarboxaldehyde oxime 4. Compounds 3 and 4 were fully characterized by IR, 1H, 13C and DEPT-135 NMR spectroscopy, elemental analyses and also by single crystal X-ray diffraction. Compounds 3 and 4 were used to remove anionic methyl blue dye from wastewater. The results established that both compounds have high adsorption capacity towards methyl blue. Langmuir adsorption capacity of compound 4 (464 mmol/g) is much higher than that of compound 3 (193 mmol/g) at 25 °C. The kinetics data was fitted well pseudo…
Synthesis and characterization of ferrocene-based Schiff base and ferrocenecarboxaldehyde oxime and their adsorptive removal of methyl blue from aque…
2018
The ferrocene-based Schiff base 3 was synthetized by reaction of ferrocenecarboxaldehyde 1 with 4-aminoantipyrine 2. However, the reaction of 1 with hydroxylamine affords ferrocenecarboxaldehyde oxime 4. Compounds 3 and 4 were fully characterized by IR, 1H, 13C and DEPT-135 NMR spectroscopy, elemental analyses and also by single crystal X-ray diffraction. Compounds 3 and 4 were used to remove anionic methyl blue dye from wastewater. The results established that both compounds have high adsorption capacity towards methyl blue. Langmuir adsorption capacity of compound 4 (464 mmol/g) is much higher than that of compound 3 (193 mmol/g) at 25 °C. The kinetics data was fitted well pseudo-second-o…
Kalcīts un tā veidošanās apstākļi Franas stāva smilšakmeņos un dolomītos Latvijā
2019
Maģistra darbā “Kalcīts un tā veidošanās apstākļi Franas stāva smilšakmeņos un dolomītos Latvijā” raksturotas kalcīta fizikālās īpašības, ķīmiskais sastāvs un veidošanās apstākļi. Pētījumi veikti 16 Amatas, Pļaviņu, Daugavas un Stipinu svītas atradnēs un atsegumos. Dokumentēti ģeoloģiskie griezumi, pētītas kalcīta fluorescences izpausmes un citas fizikālās īpašības, attiecības ar smilšakmens un dolomīta komponentiem plānslīpējumos, noteikts kalcīta ķīmiskais sastāvs un oglekļa stabilo izotopu attiecības. Secināts, ka kalcīts Amatas svītas smilšakmeņos un Pļaviņu, Daugavas un Stipinu svītas dolomītos kristalizējies līdzīgos apstākļos – no atmosfēras izcelsmes pazemes ūdeņiem sauszemes apstāk…
Performance Enhancement of a Small Animal Positron Emission Tomograph based on Continuous Crystals and Silicon Photomultipliers
2017
La tomografía por emisión de positrones (PET, por sus siglas en inglés) es una técnica de Medicina Nuclear que permite obtener de manera no invasiva imágenes funcionales “in vivo” marcando un compuesto orgánico con un emisor de positrones. Los tomógrafos PET requieren un alta resolución espacial y sensibilidad para estimar con precisión la distribución del radiotrazador en el animal. Frente a los bloques pixelados comúnmente utilizados en PET, los detectores que consisten en la combinación de cristales continuos acoplados a fotodetectores segmentados pueden ofrecer una mayor eficiencia y una alta resolución espacial. Esta última depende de la precisión de los algoritmos de determinación de …
Tetragonal tungsten bronzes Nb8−xW9+xO47−δ: optimization strategies and transport properties of a new n-type thermoelectric oxide
2015
Engineering of nanoscaled structures may help controlling the electrical and thermal transport in solids, in particular for thermoelectric applications that require the combination of low thermal conductivity and low electrical resistivity. The tetragonal tungsten bronzes Nb8−xW9+xO47 (TTB) allow a continuous variation of the charge carrier concentration while fulfilling at the same time the concept of a “phonon-glass electron-crystal” through a layered nanostructure defined by intrinsic crystallographic shear planes. The thermoelectric properties of the tetragonal tungsten bronzes Nb8−xW9+xO47−δ (0 < x < 2) were studied in the temperature range from 373 to 973 K. Structural defects and the…
Interaction en champ proche entre une sonde nanométrique et le champ de composants à cristal photonique:- interaction faible, microscopie spatialemen…
2008
With the improvement of fabrication techniques, the nanophotonics and more especially the photonics crystals which are periodic structure at the Wavelength scale have been recently developed. In this work, by using a scanning near-field optical microscope, we study such components. Firslty, we use the local probe to visualize the light distribution inside photonic crystal microcavities etched into semiconductor III/V. We focus us on the explanation of the near-field maps formation and on the probe influence on these maps. Thus, we have visualize degeneracy splitting of optical cavity modes and clearly observed in near-field cavity modes which were not visible in far-field. Moreover, in the …
Etude en champ proche et en champ lointain de composants périodiquement nanostructurés : cristaux photoniques et tamis à photons
2004
Recently, a new class of optical components is appeared. Its main characteristic is to be formed by a periodical sub-wavelength pattern, leading to the apparition of a spectral domain where propagation of light inside the structure is forbidden -- a photonic bandgap. This work is devoted to the study in the near- and far-field of two kinds of periodical optical components: photonic crystals (PCs) and nanostructured metallic films that exhibit the so-called enhanced transmission. First, we study two-dimensional PCs with a scanning near-field optical microscope (SNOM) in collection mode. With this SNOM, we directly map the intensity distribution inside PC-based microcavities. We also evidence…