Search results for "Spectroscopy"
showing 10 items of 10293 documents
Inorganic Phosphate and Arsenate within New Tetranuclear Copper and Zinc Complexes: Syntheses, Crystal Structures, Magnetic, Electrochemical, and The…
2017
Three, PO43–/HPO42– and AsO43–-incorporated, new tetranuclear complexes of copper(II) and zinc(II) ions have been synthesized and fully characterized. In methanol–water, reactions of H3cpdp (H3cpdp = N,N′-Bis[2-carboxybenzomethyl]-N,N′-Bis[2-pyridylmethyl]-1,3-diaminopropan-2-ol) with copper(II) chloride in the presence of either NaOH/Na2HPO4·2H2O or KOH/Na2HAsO4·7H2O lead to the isolation of the tetranuclear complexes Na3[Cu4(cpdp)2(μ4-PO4)](OH)2·14H2O (1) and K2[Cu4(cpdp)2(μ4-AsO4)](OH)·162/3H2O (2), respectively. Similarly, the reaction of H3cpdp with zinc(II) chloride in the presence of NaOH/Na2HPO4·2H2O yields a tetranuclear complex, Na(H3O)2[Zn4(cpdp)2(μ4-HPO4)]Cl3·121/2H2O (3). All c…
Reactivity of cellulose during hydrothermal carbonization of lignocellulosic biomass
2020
Abstract Hydrothermal carbonization (HTC) of pure cellulose (CE) and birchwood (BW) samples was carried out at temperatures between 160 and 280 °C, 0.5 h residence time and biomass-to-water ratio 1:5, to investigate the reactivity of cellulose in lignocellulosic biomass. Thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR) showed that the CE samples remained unaltered at temperatures up to 220 °C, but were significantly decomposed at 230 °C producing a thermal recalcitrant aromatic and high energy-dense material. FTIR showed that dehydration and aromatization reactions occurred at temperature equal or higher than 230 °C for the CE samples while a similar incre…
Synthesis and mesomorphism of related series of triphilic ionic liquid crystals based on 1,2,4-triazolium cations
2021
Abstract The synthesis, liquid crystal and conductivity properties of a series of 27 salts based on the 5-(4-(alkyloxy)phenyl)-1,2,4-triazol-4-ium cation bearing a perfluoroalkyl chain with triflate, tetrafluoroborate and bistriflimide anion are reported. The cations are regarded as triphilic on account of their three distinct regions – hydrocarbon, fluorocarbon and ionic. The mesophases were characterised by a combination of polarised optical microscopy, calorimetry and small-angle scattering experiments using both X-rays and neutrons, while thermal stability was probed using thermogravimetric analysis. The liquid crystal properties are found to be dependent on the anion and the length of …
Evaluation of wood-polyethylene composites biodegradability caused by filamentous fungi
2017
Abstract This study describes the impact of filamentous fungi on wood-polymer composites (WPCs) containing various types of fillers (coniferous, deciduous, cellulose) in the amount of 30 wt.% to 50 wt.%. The selection of fungal strain of filamentous fungi was performed prior to the study on the impact of the wood type on the progress of WPCs biodegradability. The changes associated with various water absorption of the examined WPCs, were observed using scanning electron microscopy (SEM). The impact of fungal mycelium, which had affected the changes in WPCs material, was examined using thermogravimetric analysis (TG). The results showed, that the growth of mycelium on WPCs, influenced mainly…
Rapid synthesis of tin (IV) oxide nanoparticles by microwave induced thermohydrolysis
2008
Abstract Tin oxide nanopowders, with an average size of 5 nm, were prepared by microwave flash synthesis. Flash synthesis was performed in aqueous solutions of tin tetrachloride and hydrochloric acid using a microwave autoclave (RAMO system) specially designed by the authors. Energy dispersive X-ray analysis (EDX), X-ray powder diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, nitrogen adsorption isotherm analysis, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM), were used to characterize these nanoparticles. Compared with conventional synthesis, nanopow…
PMMA-titania nanocomposites: Properties and thermal degradation behavior
2012
Titania nanoparticles were prepared using a solegel method and calcination at 200 and 600 � C in order to obtain anatase and rutile phases, respectively. The obtained powders were used to prepare PMMAe titania nanocomposites by a melt compounding method. The effect of the crystalline phase and the amount of titania, in the range 1e5 wt.%, on the morphology, mechanical properties and thermal degradation kinetics of PMMA was investigated by means of X-ray diffractometry (XRD), transmission electron microscopy (TEM), 13 C cross-polarization magic-angle spinning nuclear magnetic resonance spectroscopy ( 13 C{ 1 H}CP-MAS NMR), including the measurement of proton spinelattice relaxation time in t…
Bentonite-ionic liquid composites for Congo red removal from aqueous solutions
2021
Abstract Clay-organic composites have attracted great interest due to their ability to remove various contaminants from wastewater. The surfactants are the most commonly used organic compounds for clay modification. However, cationic surfactants are toxic and can be environmentally hazardous. Ionic liquids are a new promising alternative to the cationic surfactants due to lesser toxicity and appropriate thermal stability. The research aim is to prepare an environmentally friendly new class of clay sorbents modified with ionic liquids for potential applications in wastewater treatment from the textile industry. Imidazolium-based ionic liquids with different lengths of alkyl chains were inter…
In search of layered antimony(III) materials: synthesis and characterization of oxo-antimony(III) catecholate and further studies on antimony(III) ph…
1998
Abstract A new layered oxo-antimony(III) catecholate, [Sb(C6H4O2)]2O, can be obtained by reacting senarmontite with aqueous catechol. The same reaction performed with valentinite, the other allotropic form of Sb2O3, shows an intermediate hydrate that loses water at about 100°C. Both compounds can be obtained from SbPO4 under appropriate experimental conditions. [Sb(C6H4O2)]2O and the hydrated form, which appear to be layered materials, have been characterized by X-ray diffraction, thermogravimetric/differential thermal analyses, and infrared techniques. Preliminary evidence of a reversible intercalation of pyridine into [Sb(C6H4O2)]2O was collected. Taking into consideration the possible us…
The effect of feedstock origin and temperature on the structure and reactivity of char from pyrolysis at 1300–2800 °C
2018
This study reports the effect of feedstock origin, residence time, and heat treatment temperature on CO2 and O2 reactivities, nanostructure and carbon chemistry of chars prepared at 1300, 1600, 2400, and 2800 °C in a slow pyrolysis reactor. The structure of char was characterized by transmission electron microscopy and Raman spectroscopy. The CO2 and O2 reactivity of char was investigated by thermogravimetric analysis. Results showed that the ash composition and residence time influence the char reactivity less than the heat treatment temperature. The heat treatment temperature and co-pyrolysis of pinewood char with biooil decreased the CO2 reactivity, approaching that of metallurgical coke…
Complex formation of hypoxanthine and 6-mercaptopurine with Cd(II) ion
1984
Reaction of Cd(II) ion with hypoxanthine (H2 Y) and with 6-mercaptopurine (H2 MP) in dioxane-water (50%) leads to the formation of CdY·2H2O and Cd(HMP)2·2H2O, respectively. In methanolic medium Cd(II) and H2 MP give Cd(MP)·H2O. These compounds have been characterized by chemical analysis, IR spectra and thermogravimetric analysis. The stability constant of CdY complex at 25±0.1 °C and 1M ionic strength with NaClO4 in dioxane-water medium is log β=10.25±0.05.