Joule-discharge heating studies of pore connectivity in silica gel: influence of pore diameter, chemical modification, and particle size

1993 ◽  
Vol 65 (24) ◽  
pp. 3622-3630 ◽  
Author(s):  
E. H. Ellison ◽  
S. W. Waite ◽  
D. B. Marshall ◽  
J. M. Harris
Keyword(s):  
Particle Size ◽  
Chemical Modification ◽  
Silica Gel ◽  
Pore Diameter ◽  
Pore Connectivity

Fine-Grained Concrete with Nanodispersed Silica Additive

2020 ◽  
Vol 992 ◽  
pp. 156-161
Author(s):  
N.P. Lukuttsova ◽  
E.G. Borovik ◽  
D.A. Pehenko
Keyword(s):  
Particle Size ◽  
Compressive Strength ◽  
Pore Diameter ◽  
Fine Grained ◽  
Silica Concentration ◽  
Calcium Hydrosilicates ◽  
Additive Particle ◽  
Nanodispersed Silica ◽  
Silica Additive ◽  
Number Of Particles

The effect of the modifying nanodispersed silica (NS) additive, obtained by the polycondensation method, on the properties of fine-grained concrete (FGC) is studied. It is revealed that the dependence of the NS-additive particle size on its age is extreme. The maximum number of particles of up to 100 nm in the additive is observed at the age of 10 days, and then their number decreases. However, it affects the FGC strength little even after 30 days of the additive storage. It is established that the NS-additive could be most effectively used with 0.23% of an active silica concentration and pH 4.1 in combination with S-3. At that, the porosity declines from 17.5 to 12.9% and the pore diameter diminishes from 3.171 to 0.689 μm. It leads to an increase in the compressive strength by 2 times and a decrease in water absorption by 1.6 times as compared to the control composition without additives. An increase in the frost resistance of the modified fine-grained concrete to F250 is recorded; it occurs due to a decrease in porosity at portlandite binding with amorphous silica additives into low-basic calcium hydrosilicates.

scholarly journals Nanoporous smartPearls for dermal application – Identification of optimal silica types and a scalable production process as prerequisites for marketed products

2019 ◽  
Vol 10 ◽  
pp. 1666-1678 ◽  
Author(s):  
David Hespeler ◽  
Sanaa El Nomeiri ◽  
Jonas Kaltenbach ◽  
Rainer H Müller
Keyword(s):  
Particle Size ◽  
Production Process ◽  
Pore Diameter ◽  
Active Agent ◽  
Amorphous State ◽  
Silica Particles ◽  
Batch Size ◽  
Maximum Loading ◽  
Rotary Evaporator ◽  
Scalable Production

smartPearls are a dermal delivery system for poorly soluble active agents, consisting of nanoporous silica particles loaded with a long-term stable, amorphous active agent in its mesopores (2–50 nm). The amorphous state of the active agent is known to increase dermal bioavailability. For use in marketed products, optimal silica types were identified from commercially available, regulatory accepted silica. In addition, a scalable production process was demonstrated. The loading of the particles was performed by applying the immersion–evaporation method. The antioxidant rutin was used as a model active agent and ethanol was applied as the solvent. Various silica particles (Syloid®, Davisil®) differing in particle size (7–50 µm), pore diameter (3–25 nm) and pore volume (0.4–1.75 mL/g) were investigated regarding their ease of processing. The evaporation from the silica–ethanol suspensions was performed in a rotary evaporator. The finest powders were obtained with larger-sized silica. The maximum loading staying amorphous was achieved between 10% and 25% (w/w), depending on the silica type. A loading mechanism was also proposed. The most suitable processing occurred with the large-sized Syloid® XDP 3050 silica with a 50 µm particle size and a pore diameter of 25 nm, resulting in 18% (w/w) maximum loading. Based on a 10% (w/w) loading and the amorphous solubility of the active agent, for a 100 kg dermal formulation, about 500 g of loaded particles were required. This corresponds to production of 5 kg of loaded smartPearls for a formulation batch size of a ton. The production of 5 kg (i.e., about 25 L of solvent removal) can be industrially realized in a commercial 50 L rotary evaporator.

Sorption and desorption of uranyl ions by silica gel: pH, particle size and porosity effects

1996 ◽  
Vol 5 (5) ◽  
pp. 309-324 ◽  
Author(s):  
P. Michard ◽  
E. Guibal ◽  
T. Vincent ◽  
P. Le Cloirec
Keyword(s):  
Particle Size ◽  
Silica Gel ◽  
Uranyl Ions ◽  
Gel Ph

Validation of HPTLC and HPLC Methods for the Quantitative Determination of Allyl Disulfide in Some Polyherbal Oils

2012 ◽  
Vol 95 (6) ◽  
pp. 1574-1578
Author(s):  
Nitin Dubey ◽  
Nidhi Dubey ◽  
Rajendra Mehta
Keyword(s):  
Particle Size ◽  
Quantitative Determination ◽  
Silica Gel ◽  
Vegetable Oil ◽  
Flow Rate ◽  
Mobile Phase ◽  
Allium Sativum ◽  
Hplc Separation ◽  
Reliable Marker

Abstract Allium sativum L (garlic) is an essential component of many polyherbal oils used in traditional systems of medicine. Allyl disulfide has been a major component found in vegetable oil macerate of garlic, and can be used as reliable marker for determination of garlic in oil macerates of garlic. The HPLC separation of allyl disulfide was achieved on a Phenomenex Luna C18 (25 cm × 4.6 mm id × 5 μm particle size) column using acetonitrile–water–tetrahydrofuran (70 + 27 + 3, v/v/v) mobile phase at a flow rate of 1.0 mL/min. Quantitation was achieved with UV detection at 298 nm over the concentration range 8–48 μg/mL. HPTLC separation of allyl disulfide was achieved on an aluminum-backed layer of silica gel 60 F254 using n-hexane mobile phase. Quantitation was achieved by densitometric analysis at 298 nm over the 200–1200 ng/band concentration range. The methods were validated according to International Conference on Harmonization guidelines.

Particle-Size Optimization for a Polymer Coated Silica Gel in SMB Chromatography for Amino Acid Separation

2009 ◽  
Vol 32 (19) ◽  
pp. 2822-2838 ◽  
Author(s):  
Se-Hee Jo ◽  
Qiao Han ◽  
Young-Woong Suh ◽  
Jin-Bok Ryu ◽  
Sung Chul Yi ◽  
...  
Keyword(s):  
Particle Size ◽  
Amino Acid ◽  
Silica Gel ◽  
Size Optimization

Fabrication of Porous SiAlON Using Fe2O3 as Pore Former

2014 ◽  
Vol 804 ◽  
pp. 267-270
Author(s):  
Qing Wen Duan ◽  
Rong Zhen Liu ◽  
Hai Yun Jin ◽  
Jian Feng Yang ◽  
Zhi Hao Jin
Keyword(s):  
Particle Size ◽  
Porous Materials ◽  
Pore Size ◽  
Fracture Mode ◽  
Size Effects ◽  
Pore Diameter ◽  
Bending Strength ◽  
Thermal Reduction ◽  
Pore Former ◽  
Median Pore

Porous SiAlON ceramics were fabricated by carbo-thermal reduction nitridation method using Fe2O3 as pore former. Particle size effects of Fe2O3 were reported in this paper. The results showed that composites were composed by SiAlON, AlN and Iron Silicon phases. The median pore diameter of Sialon was affected by the composition and particle size of Fe2O3. The fracture mode of this material was intergranular. With the increase of Fe2O3 additions, the porosity of this materials increased. The bending strength of this material was reversely proportional to Fe2O3 particle size. The maximum bending strength of Porous materials with 30wt.% Fe2O3 additions (with a porosity about 65% and the pore size is about 1μm) could reach 22 MPa. The porous Sialon ceramics with a smaller pore size exhibited a higher bending strength.

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