The effect of Na2CO3, NaF and NH4OH on the stability and release behavior of sol–gel derived silica xerogels embedded with bioactive compounds

This work successfully prepared an UV curable organic-inorganic hybrid material consisting of organic modified colloidal silica. Applications of UV curable organic-inorganic hybrid materials include abrasion resistant coatings, photo-patternable thin films and waveguides. Colloidal silica containing reactive functional groups were also prepared by reacting organic silane and tetraethyl orthosilicate (TEOS) using sol-gel process. In addition, the efficiency of grafting organic moiety onto silica nanoparticles was investigated by applying TGA and FTIR techniques. Experimental results indicated a strong interdependence between surface modification efficiency and solution pH. Acrylate-SiO2 hybrid formation could result in a shifting of thermal degradation temperature of organic component from about 200°C to near 400°C. In addition, the stability of organic modified colloidal silica in UV curable formula and the physical properties of resulting coatings were discussed. Furthermore, the morphology of organic modified colloidal silica was investigated by performing TEM and SEM studies‥

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Probing the Effect of Titanium Substitution on the Sodium Storage in Na3Ni2BiO6 Honeycomb-Type Structure

Energies ◽

10.3390/en13246498 ◽

2020 ◽

Vol 13 (24) ◽

pp. 6498

Author(s):

Eugen Zemlyanushin ◽

Kristina Pfeifer ◽

Angelina Sarapulova ◽

Martin Etter ◽

Helmut Ehrenberg ◽

...

Keyword(s):

Critical Concentration ◽

Sol Gel ◽

Honeycomb Structure ◽

Electrochemical Process ◽

Electrochemical Kinetics ◽

Fast Diffusion ◽

Reversible Phase Transition ◽

Synchrotron Radiation Diffraction ◽

Na Ions ◽

The Stability

Na3Ni2BiO6 with Honeycomb structure suffers from poor cycle stability when applied as cathode material for sodium-ion batteries. Herein, the strategy to improve the stability is to substitute Ni and Bi with inactive Ti. Monoclinic Na3Ni2-xBi1-yTix+yO6 powders with different Ti content were successfully synthesized via sol gel method, and 0.3 mol of Ti was determined as a maximum concentration to obtain a phase-pure compound. A solid-solution in the system of O3-NaNi0.5Ti0.5O2 and O3-Na3Ni2BiO6 is obtained when this critical concentration is not exceeded. The capacity of the first desodiation process at 0.1 C of Na3Ni2BiO6 (~93 mAh g−1) decreases with the increasing Ti concentration to ~77 mAh g−1 for Na3Ni2Bi0.9Ti0.1O6 and to ~82 mAh g−1 for Na3Ni0.9Bi0.8Ti0.3O6, respectively. After 100 cycles at 1 C, a better electrochemical kinetics is obtained for the Ti-containing structures, where a fast diffusion effect of Na+-ions is more pronounced. As a result of in operando synchrotron radiation diffraction, during the first sodiation (O1-P3-O’3-O3) the O’3 phase, which is formed in the Na3Ni2BiO6 is fully or partly replaced by P’3 phase in the Ti substituted compounds. This leads to an improvement in the kinetics of the electrochemical process. The pathway through prismatic sites of Na+-ions in the P’3 phase seems to be more favourable than through octahedral sites of O’3 phase. Additionally, at high potential, a partial suppression of the reversible phase transition P3-O1-P3 is revealed.

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Small-angle scattering investigation of silica xerogels and sonogels prepared with ionic liquid pyridinium tetrafluoroborate

Processing and Application of Ceramics ◽

10.2298/pac1703229a ◽

2017 ◽

Vol 11 (3) ◽

pp. 229-233 ◽

Cited By ~ 2

Author(s):

László Almásy ◽

Ana-Maria Putz ◽

Adél Len ◽

Josef Plestil ◽

Cecilia Savii

Keyword(s):

Ionic Liquid ◽

Small Angle ◽

Sol Gel ◽

Molar Ratio ◽

Strong Increase ◽

Silica Xerogels ◽

X Ray Scattering ◽

Angle Scattering ◽

Gel Processing ◽

Functionalized Alkoxide

Silica matrices were prepared via acid catalysed sol-gel processing augmented with sonocatalysis. As silica precursors, a mixture of tetra-functionalized alkoxide (TMOS) and three-functionalized alkoxide methyl-trimethoxysilane (MTMS) were employed. Ionic liquid N-butyl-3-methylpyridinium tetrafluoroborate ([bmPy][BF4]), was used in various proportions, aiming to catalyse the sol-gel reactions, and to influence the mesoporous silica materials properties, serving as pore template. Small-angle neutron (SANS) and small-angle X-ray scattering (SAXS) techniques were used to explore the xerogels and sonogels microstructure evolution as a function of the IL/Si molar ratio. The results show a strong increase of the primary particle size under the influence of the ionic liquid. Ultrasonic agitation leads to further size increase by ca. 10%.

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Kinetics and mechanism of sol-gel transformation between some trivalent- and tetravalent-metal ions and Sodium alginate Anionic polyelectrolyte with formation of coordination Biopolymeric structure polymembranes Hydrogels of Capillary Structures Ex

JOURNAL OF ADVANCES IN CHEMISTRY ◽

10.24297/jac.v3i1.914 ◽

2007 ◽

Vol 3 (1) ◽

pp. 133-142 ◽

Cited By ~ 1

Author(s):

Ishaq Abdullah Zaafarany

Keyword(s):

Sodium Alginate ◽

Metal Ion ◽

Sol Gel ◽

Coordination Geometry ◽

Large Excess ◽

First Order ◽

Pseudo First Order ◽

The Stability ◽

Kinetics Of ◽

Overall Kinetics

Abstract The kinetics of sol-gel transformation between A13+, La 3+ and Th4+ metal ion electrolytes and sodium alginate sol have been studied complexometrically at various temperatures. In the presence of a large excess of sodium alginate sol concentration over that of metal ion electrolyte, the pseudo first–order plots of exchange showed sigmoidal curves with two distinct stages. The initial part was relatively fast and curved significantly at early times, followed by a slow decrease in the rates of exchange over longer time periods. The rate constants of gelation showed second-order overall kinetics which was first order in the concentration of both reactants. The thermodynamic parameters have been evaluated and tentative gelation mechanisms consistent with the kinetic results of gelation are suggested. The stability of these ionotropic metal-alginate complexes has been discussed in terms of the coordination geometry and strength of chelated bonds.

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In Vitro Release of Cisplatin from Sol-Gel Processed Porous Silica Xerogels

Drug Delivery ◽

10.1080/10717540490507451 ◽

2004 ◽

Vol 11 (6) ◽

pp. 341-344 ◽

Cited By ~ 16

Author(s):

K. Czarnobaj ◽

J. Łukasiak

Keyword(s):

Sol Gel ◽

In Vitro Release ◽

Porous Silica ◽

Silica Xerogels ◽

Vitro Release

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Chemical Preparation Routes and Lowering the Sintering Temperature of Ceramics

Ceramics ◽

10.3390/ceramics3030029 ◽

2020 ◽

Vol 3 (3) ◽

pp. 312-339

Author(s):

Philippe Colomban

Keyword(s):

Electrode Materials ◽

Sintering Temperature ◽

Microwave Sintering ◽

Sol Gel ◽

Transient Liquid Phase ◽

Ceramic Matrix Composites ◽

Thermomechanical Properties ◽

Matrix Composites ◽

Chemical Preparation ◽

The Stability

Chemically and thermally stable ceramics are required for many applications. Many characteristics (electrochemical stability, high thermomechanical properties, etc.) directly or indirectly imply the use of refractory materials. Many devices require the association of different materials with variable melting/decomposition temperatures, which requires their co-firing at a common temperature, far from being the most efficient for materials prepared by conventional routes (materials having the stability lowest temperature determines the maximal firing temperature). We review here the different strategies that can be implemented to lower the sintering temperature by means of chemical preparation routes of oxides, (oxy)carbides, and (oxy)nitrides: wet chemical and sol–gel process, metal-organic precursors, control of heterogeneity and composition, transient liquid phase at the grain boundaries, microwave sintering, etc. Examples are chosen from fibers and ceramic matrix composites (CMCs), (opto-)ferroelectric, electrolytes and electrode materials for energy storage and production devices (beta alumina, ferrites, zirconia, ceria, zirconates, phosphates, and Na superionic conductor (NASICON)) which have specific requirements due to multivalent composition and non-stoichiometry.

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Stability of Kiwi Varieties of ‘Hayward’ in Powder During Storage

Journal of Agricultural Studies ◽

10.5296/jas.v8i2.15689 ◽

2020 ◽

Vol 8 (2) ◽

pp. 150

Author(s):

Inacia Dos Santos Moreira ◽

Jacinete Pereira Lima ◽

Deise Souza de Castro ◽

Wilton Pereira da Silva ◽

Josivanda Palmeira Gomes ◽

...

Keyword(s):

Water Activity ◽

Bioactive Compounds ◽

Titratable Acidity ◽

Physicochemical Characteristics ◽

Soluble Solids ◽

Total Chlorophyll ◽

Lower Content ◽

Total Water ◽

Ph Values ◽

The Stability

For the preservation of products obtained by dehydration, it is necessary to evaluate their physicochemical characteristics during storage. It was proposed, in the present study, to evaluate the stability of the kiwi cv. ‘Hayward’ powder, obtained at temperatures of 60 and 70 °C during its storage in laminated packages under controlled conditions of temperature (25 ºC) and relative humidity (75%) for 90 days. The parameter’s evaluated were: moisture content, ashes, soluble solids, titratable acidity (% citric acid), pH, water activity at 25 ºC, color for the parameters lightness (L*) and chromaticity (+a* red; -a* green; +b* yellow; and -b* blue), phenolic compounds, flavonoids, total chlorophyll and carotenoids. It was observed that, after the 90 days, for the powder obtained at 70 °C, the soluble solids and pH values were altered by the storage, which did not occur for the powder obtained at 60 °C. For both powders, the content of ash and bioactive compounds were not affected by storage. The parameter of lightness decreased in both powders. The powder obtained at 70 ºC proved to be better, showing lower content of moisture and total water activity, as well as the highest values of bioactive compounds.

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