Application of Infrared Spectroscopy in Honey Analysis

The chemical composition and sensory characteristics vary significantly within different honey types. In order to determine botanical origin of honey, it is necessary to conduct rather complicated and time consuming analytical methods. IR spectroscopy has not yet been experimentally explored for honey analysis in Croatia, so the aim of this study was to determine claimed botanical origin of honey using both, standard and alternative (IR spectroscopy) methods, for the purpose of their comparison, Altogether 144 samples of nine different unifloral honey types (black locust, sweet chestnut, lime, sage, heath, rosemary, lavender, mandarin and strawberry tree) were collected from different Croatian regions directly from the beekeepers. In order to confirm claimed botanical origin of collected honey samples, melissopalinological analysis, moisture and electrical conductivity measurements were conducted. Infrared spectra of honey samples were recorded using the ABB Bomem MB102 Fourier-transform infrared spectrometer (FT-IR spectrometer). Selected IR spectral regions were analyzed by multivariate data analysis, principal components analysis (PCA). Preliminary PCA of IR spectra showed significant clustering of the analyzed samples by botanical origin. The results of this study showed that IR spectroscopy provides reliable results, but also represents rapid and cheap analytical tool in comparison to commonly used standard analytical methods. This research has also provided the first insight in infrared spectra of Croatian honeys

Interaction of light alkali metals with ammonia borane: a theoretical study

Ammonia borane – AB (formula: NH3-BH3) has been known for its extraordinary gravimetric hydrogen capacity (nearly 20 wt.%) and is therefore considered as promising hydrogen storage material. However, there are several drawbacks to overcome, namely dehydrogenation kinetics is rather poor, and three-step desorption releases contaminated hydrogen with each subsequent step requiring significantly higher temperature. In addition, there are detrimental by-products (e.g., borasine, diborane) that also limit its practical application. Eliminating at least borasine release is possible through the reaction of alkali metal (M=Li, Na) with AB and producing monometallic amidoborane salts MAB. In this paper, electronic structure calculations and the analysis of charge density topology of pure AB, lithium, and sodium amidoboranes were performed in order to investigate cohesion and bonding nature. The influence of the specific alkali metal substitution will be assessed using calculated IR and Raman spectra and analysis of vibrational bands in comparison to pure AB.4IMMSERA - 4th International Meeting on Materials Science for Energy Related Applications ; September 22-23, 2021 ; Online meeting4th International Meeting on Materials Science for Energy Related Applications held on September 22-23, 2021 at the University of Belgrade, Faculty of Physical Chemistry, Belgrade, Serbia (online meeting) is a satellite event of PHYSICAL CHEMISTRY 2021 15th International Conference on Fundamental and Applied Aspects of Physical Chemistry Organized by UNIVERSITY OF BELGRADE FACULTY OF PHYSICAL CHEMISTRY Belgrade, Serbi

Is WO3 catalyst for hydrogen desorption?

Magnesium hydride, as hydrogen storage material, meets the requirements such as high gravimetric hydrogen capacity (7,6 wt%), low cost and weight, abundance and H2 absorption/desorption cycling possibility. Given that the oxide additives show the good impact on desorption properties, mechanical milling of MgH2 with addition of 5, 10 and 15% wt. WO3 was performed. The microstructure and morphology of composites were analysed by XRD, PSD and SEM and correlated to hydrogen desorption properties which have been investigated by DSC. The results have shown that WO3 has a positive effect on the desorption kinetics as well as on the change of the desorption mechanism

Mechanochemical Metathesis between AgNO3 and NaX (X = Cl, Br, I) and Ag2XNO3 Double-Salt Formation

Here we describe real-time, in situ monitoring of mechanochemical solid-state metathesis between silver nitrate and the entire series of sodium halides, on the basis of tandem powder X-ray diffraction and Raman spectroscopy monitoring. The mechanistic monitoring reveals that reactions of AgNO3 with NaX (X = Cl, Br, I) differ in reaction paths, with only the reaction with NaBr providing the NaNO3 and AgX products directly. The reaction with NaI revealed the presence of a novel, short-lived intermediate phase, while the reaction with NaCl progressed the slowest through the well-defined Ag2ClNO3 intermediate double salt. While the corresponding iodide and bromide double salts were not observed as intermediates, all three are readily prepared as pure compounds by milling equimolar mixtures of AgX and AgNO3. The in situ observation of reactive intermediates in these simple metathesis reactions reveals a surprising resemblance of reactions involving purely ionic components to those of molecular organic solids and cocrystals. This study demonstrates the potential of in situ reaction monitoring for mechanochemical reactions of ionic compounds as well as completes the application of these techniques to all major compound classes

Is WO3 catalyst for hydrogen desorption?

Magnesium hydride, as hydrogen storage material, meets the requirements such as high gravimetric hydrogen capacity (7,6 wt%), low cost and weight, abundance and H2 absorption/desorption cycling possibility. Given that the oxide additives show the good impact on desorption properties, mechanical milling of MgH2 with addition of 5, 10 and 15% wt. WO3 was performed. The microstructure and morphology of composites were analysed by XRD, PSD and SEM and correlated to hydrogen desorption properties which have been investigated by DSC. The results have shown that WO3 has a positive effect on the desorption kinetics as well as on the change of the desorption mechanism