Proton conductivity of Nafion/ex situ Stöber silica nanocomposite membranes as a function of silica particle size and temperature

2013 ◽  
Vol 49 (4) ◽  
pp. 1566-1573 ◽  
Author(s):  
Beatrice Muriithi ◽  
Douglas A. Loy
Keyword(s):  
Particle Size ◽  
Proton Conductivity ◽  
Silica Particle ◽  
Ex Situ ◽  
Nanocomposite Membranes ◽  
Silica Nanocomposite

Ultrafiltration of silica sols

1989 ◽  
Vol 54 (1) ◽  
pp. 91-101 ◽  
Author(s):  
Milan Stakić ◽  
Slobodan Milonjić ◽  
Vladeta Pavasović ◽  
Zoja Ilić
Keyword(s):  
Particle Size ◽  
Silica Particle ◽  
Specific Resistance ◽  
Membrane Surface ◽  
Membrane Resistance ◽  
Experimental Conditions ◽  
Surface Unit ◽  
Silica Sols ◽  
Filtration Flux ◽  
Batch Cell

Ultrafiltration of three laboratory made silica and two commercial silica sols was studied using Amicon YC membrane in a 200 ml capacity batch-cell. The effect of silica particle size, stirring conditions, pressure, pH and silica contents on ultrafiltration was investigated. The results obtained indicate that the smaller particles have, disregarding the stirring conditions, lower filtration flux. The differences observed in filtration flux are more pronounced in the conditions without stirring. The obtained value of the membrane resistance is independent of the conditions investigated (stirring, pressure, pH, silica contents and particle size). The values of the resistance of polarized solids, specific resistance, and the mass of gel per membrane surface unit were calculated for all experimental conditions.

scholarly journals In Situ Synthesis of Core-Shell-Structured SiCp Reinforcements in Aluminium Matrix Composites by Powder Metallurgy

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1201
Author(s):  
Xinghua Ji ◽  
Cheng Zhang ◽  
Shufeng Li
Keyword(s):  
Particle Size ◽  
Powder Metallurgy ◽  
Shell Structure ◽  
Ex Situ ◽  
Aluminium Matrix ◽  
Core Shell ◽  
Matrix Composites ◽  
Aluminium Matrix Composites ◽  
Core Shell Structure

SiCp reinforced aluminium matrix composites (AMCs), which are widely used in the aerospace, automotive, and electronic packaging fields along with others, are usually prepared by ex situ techniques. However, interfacial contamination and poor wettability of the ex situ techniques make further improvement in their comprehensive performance difficult. In this paper, SiCp reinforced AMCs with theoretical volume fractions of 15, 20, and 30% are prepared by powder metallurgy and in situ reaction via an Al-Si-C system. Moreover, a combined method of external addition and an in situ method is used to investigate the synergistic effect of ex situ and in situ SiCp on AMCs. SiC particles can be formed by an indirect reaction: 4Al + 3C → Al4C3 and Al4C3 + 3Si → 3SiC + 4Al. This reaction is mainly through the diffusion of Si, in which Si diffuses around Al4C3 and then reacts with Al4C3 to form SiCp. The in situ SiC particles have a smooth boundary, and the particle size is approximately 1–3 μm. A core-shell structure having good bonding with an aluminium matrix was generated, which consists of an ex situ SiC core and an in situ SiC shell with a thickness of 1–5 μm. The yield strength and ultimate tensile strength of in situ SiCp reinforced AMCs can be significantly increased with a constant ductility by adding 5% ex situ SiCp for Al-28Si-7C. The graphite particle size has a significant effect on the properties of the alloy. A criterion to determine whether Al4C3 is a complete reaction is achieved, and the forming mechanism of the core-shell structure is analysed.

Rice Hull Micro and Nanosilica: Synthesis and Characterization

2016 ◽  
Vol 718 ◽  
pp. 77-80 ◽  
Author(s):  
Worawat Jansomboon ◽  
Khatawut Boonmaloet ◽  
Suradet Sukaros ◽  
Paweena Prapainainar
Keyword(s):  
Particle Size ◽  
Silica Nanoparticles ◽  
Sodium Silicate ◽  
Silica Particle ◽  
Precipitation Method ◽  
Rice Hull ◽  
Synthesis And Characterization ◽  
Natural Material ◽  
Silica Microparticles ◽  
Temperature Levels

Rice hull is a by-product natural material composing of high amount of silica. In this work, silica microparticles were synthesized from rice hull using 3 temperature levels of calcination at 500, 600, and 850 ºC. Then, they were transformed to silica nanoparticles by precipitation method using sodium silicate as an initial substance synthesized from rice hull. Finally, the properties of silica particle were studied such as characteristics, morphology of particle, component, and size of silica. The result showed the silica structure became more crystalline when the temperature was increased. When the concentration of sodium silicate increased, more agglutination occurred in the silica structure. The results also indicated that the particle size and component of silica synthesized by heating rice hull at 600 ºC followed by precipitation method were the same as those of commercial silica.

Inferring suspended sediment carbon content and particle size at high frequency from the optical response of a submerged spectrometer 

2021 ◽  
Author(s):  
Dhruv Sehgal ◽  
Núria Martínez-Carreras ◽  
Christophe Hissler ◽  
Victor Bense ◽  
AJF (Ton) Hoitink
Keyword(s):  
Particle Size ◽  
Absorption Spectrum ◽  
Carbon Content ◽  
Suspended Sediment ◽  
High Frequency ◽  
Suspended Sediments ◽  
Ex Situ ◽  
Frequency Measurements ◽  
Component Form

<p>Manual and unattended sampling in the field and laboratory analysis are common practices to measure suspended sediment (SS) carbon content and particle size. However, one of the major drawbacks of these ex-situ methods is that they make high frequency measurements challenging. This includes restricted data collection due to limited access to the sampling locations during turbulent conditions or high flows, when the largest amount of sediments is transported downstream, introducing uncertainty in quantification of SS properties (particle size and carbon content) and sediment loads. Knowledge on SS carbon content and particle size is also important to better understand the multi-component form of suspended sediments (i.e. flocs) that directly affect sediment transport and other sediment properties (e.g. settling velocity and density). Moreover, SS carbon content and particle size exert an impact on the optical sensor readings that are traditionally used to measure turbidity. In that respect, high frequency measurements of SS carbon content and particle size could eventually help us to move from ‘local’ calibrations towards ‘global’ dependencies based on in-situ SS characterization.</p><p>In this study, we propose to use a submerged UV-VIS spectrometer to infer SS carbon content and particle size. The sensor measures the entire light absorption spectrum of water between 200 nm and 750 nm at sampling intervals as short as 2-minutes. To this end, we first test our approach under controlled conditions with an experimental laboratory setup consisting of a cylindrical tank (40-L) with an open top. An UV-VIS spectrometer and a LISST-200X sensor (to measure particle size distribution) are installed horizontally. A stirrer facilitates the homogeneous mixing of SS and prevents the settling of heavy particles at the bottom. We use the sediments sampled from 6 sites in Luxembourg with contrasting composition and representing different land use types and geological settings. The sampled sediments were wet sieved into 3 size classes to clearly recognize the effect of particle size on absorption. In our investigation, we use specific wavelengths, chemometric techniques and carbon content specific absorbance indices to infer SS composition and particle size from the absorption spectrum. Results are then validated using in-situ field data from two instrumented field sites in Luxembourg. Amid the challenge of associating laboratory and field results, the preliminary results indicate that the absorption spectrum measured with a submerged UV-VIS spectrometer can be used to estimate SS particle size and carbon content.</p>

Sign in / Sign up

Export Citation Format

Share Document