Experimental setup for spectrophotometric study of water clusters in nanoporous material

Lugovskoy, Alex; Poplavskiĭ, Yu. A.; Serdyukov, V. I.; Sinit︠s︡a, L. N.

doi:10.1134/s1024856011050125

Cited by 12 publications

(2 citation statements)

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“…This is indicated by an intense maximum at 3300 cm -1 , corresponding to stretching vibrations of О-Н (n(ОН)) bonds in water molecules connected by hydrogen bonds. The band at 1640 cm -1 corresponds to deformation vibrations (δ (HON)) of water molecules; intensive absorption in the 800...400 cm -1 region is due to the librational (rotational) vibrations of water molecules in the liquid phase (n L (H 2 O)), and the absorption band at 2030 cm -1 corresponds to the frequency (δ+n L ) [8].…”

Section: Resultsmentioning

confidence: 99%

Formation of Technological Indices of Dry Powder of Cabbage

Niemirich

Vasheka

Petrusha

et al. 2018

EUREKA: Life Sciences

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One of the resource-saving methods of drying, from the point of view of preserving food and biological value, providing the appropriate recovery properties of dried food products (DFP) and energy intensity of the process, is drying with mixed heat supply (MHS drying). The scientific concept of work on the formation of a universal and DFP stable functional and technological potential is formulated, which is the basis for modeling and designing the formulation composition and technology of food products by groups and types with its use or interchangeability. As the subject of research for the formation of quality indicators of cereals, white cabbage is selected, as it is a typical vegetable for Ukraine and accordingly has a high degree of assimilation of natural micronutrients in the human body. Structural studies have shown the predominantly crystalline structure of polysaccharides, that is, less than their transformation under conditions of MHS drying, as compared with convective conditions. The effect of MHS drying on the formation of DFP quality indicators is determined by the method of recording IR spectra with Fourier transform. For studies of the violation of total internal reflection, it has been established that the process of DFP reduction leads to an increase in the availability of organic substances in the solvent, which will facilitate the extraction of extractives in the recovery of raw materials. It is established by the number of aroma, the more aromatic-forming substances are contained in the MHS drying samples irrespective of the process temperature, less in the dried samples of the convective method. This is due to the reduction of thermal and thermal effects during MHS drying, which slows down chemical transformations and removes aromatic substances. It is proved by the tensometric method, with the convective method due to shrinkage during dehydration, the changes during sorption and desorption are insignificant. When MHS drying, such changes are expressed: during the sorption of vapors, DFP is well restored, the capillaries swell, so the differential distribution function of the pores expands, the average radius of the capillaries increases 4...6 times. The research results make it possible to form the functional and technological parameters of cabbage powder, to simulate the formulation of new food products with this ingredient and to optimize the production technology.

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Section: Resultsmentioning

confidence: 99%

Formation of Technological Indices of Dry Powder of Cabbage

Niemirich

Vasheka

Petrusha

et al. 2018

EUREKA: Life Sciences

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“…Considerable water desorbs around 100 °C, but its continued evolution up to the onset of consolidation of PVG, ca. 650 °C, indicates strong interactions with the silica surface, which in turn suggests significant changes in its properties. ,, Theoretical and experimental studies report interactions ranging from water clustering to hydrolytic weakening and dissociative chemisorption; − all of which are expected to change the energetics of the redox chemistry of chemisorbed water. Assuming chemisorption of water reduces its oxidation potential from the aqueous solution value, −1.23 V (Figure , line e), to −1.0 V (Figure , line d), for example, reduces the ΔpH that must be achieved by excitation of WO 3 or the mixed valence oxide from ΔpH of ∼21 to ∼14.…”

Section: Discussionmentioning

confidence: 99%

Photocatalyzed Conversion of CO₂to CH₄: An Excited-State Acid–Base Mechanism

Look

Gafney

2013

J. Phys. Chem. A

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Photoinduced reduction of CO2 by H2O occurs in nanoporous Vycor glass doped with tungsten oxides derived from 312 nm photolysis of physisorbed W(CO)6. In polished forms of Vycor, a hydrated precursor to monoclinic WO3 is formed, whereas in the unpolished glass, the WO3 precursor and mixed valence tungsten oxides that exhibit lower energy intervalence charge transfer (IVCT) transitions are formed. The relative amounts of the different tungsten oxide are attributed to structural differences between the polished and unpolished forms of PVG. Chemisorption converts CO2 to a formic acid-like species, and population of the conduction band of the WO3 precursor with 312 nm light or population of the IVCT state of the mixed valence oxide with ≥437 nm light photocatalyzes the reduction of chemisorbed by coadsorbed water yielding CH4 and O2. Regardless of the excitation wavelength, electronic spectra and the dependence of methane yield on absorbed energy and the energetics of the conversions implies that neither metal oxide acts as a source of reducing equivalents. Instead, excitation of the metal oxide induces a charge polarization that creates local acidic and basic regions about the oxide in which the reduction of chemisorbed CO2 and oxidation of chemisorbed H2O occur exergonically. The dependence of methane yield on surface pH, and the pH dependencies of the respective half reactions show that the pH gradient needed for the reactions to occur spontaneously fall within the range of known photoinduced changes in acid-base properties. Within this excited-state acid-base mechanism, the metal oxide is not a source of electrons, but a conduit of electrons and protons between two exergonic processes.

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