Determination of interaction forces and average pore size and pore size distribution and their effects on fouling of ultrafiltration membranes

1984 ◽  
Vol 23 (1) ◽  
pp. 116-124 ◽  
Author(s):  
Tinghui Liu ◽  
Chan Kam ◽  
Takeshi Matsuura ◽  
S. Sourirajan
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Average Pore Size ◽  
Ultrafiltration Membranes ◽  
Average Pore ◽  
Interaction Forces

Evaluation of the Effect of Catalyst Pore-Size Distribution on the Effectiveness Factor in Ethylbenzene Dehydrogenation by Orthogonal Collocation

2011 ◽  
Vol 316-317 ◽  
pp. 155-169
Author(s):  
Mohammad Ebrahim Zeynali
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Average Pore Size ◽  
Effectiveness Factor ◽  
Orthogonal Collocation ◽  
Average Pore ◽  
Catalyst Pellet ◽  
Pore Size Distributions ◽  
Styrene Production

The mathematical model for multicomponent diffusion in styrene production is given considering all six reactions involved in styrene production. The diffusion coefficients for catalyst pellet are calculated for unimodal and bimodal pore size distributions using trapezoidal rule of integration. The effects of standard deviation and average pore size on the diffusion coefficient are determined. The differential equations are converted to algebraic equations and solved by the orthogonal collocation method. The effectiveness factor of catalyst pellet in styrene production is calculated for various pore sizes. It is seen that the average pore size and pore size distribution affects the production rate and effectiveness factor significantly.

Probing Pore Characteristics in Low-K Thin Films Using Positronium Annihilation Lifetime Spectroscopy

2000 ◽  
Vol 612 ◽  
Author(s):  
D. W. Gidley ◽  
W. E. Frieze ◽  
T. L. Dull ◽  
J. N. Sun ◽  
A. F. Yee
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Average Pore Size ◽  
Gas Absorption ◽  
Porous Films ◽  
Pore Characteristics ◽  
Average Pore ◽  
Positronium Annihilation ◽  
Positronium Annihilation Lifetime Spectroscopy

AbstractDepth profiled positronium annihilation lifetime spectroscopy (PALS) has been used to probe the pore characteristics (size, distribution, and interconnectivity) in thin, porous films, including silica and organic-based films. The technique is sensitive to all pores (both interconnected and closed) in the size range from 0.3 nm to 300 nm, even in films buried under a diffusion barrier. PALS may be particularly useful in deducing the pore-size distribution in closed-pore systems where gas absorption methods are not available. In this technique a focussed beam of several keV positrons forms positronium (Ps, the electron-positron bound state) with a depth distribution that depends on the selected positron beam energy. Ps inherently localizes in the pores where its natural (vacuum) annihilation lifetime of 142 ns is reduced by collisions with the pore surfaces. The collisionally reduced Ps lifetime is correlated with pore size and is the key feature in transforming a Ps lifetime distribution into a pore size distribution. In thin silica films that have been made porous by a variety of methods the pores are found to be interconnected and an average pore size is determined. In a mesoporous methyl-silsesquioxane film with nominally closed pores a pore size distribution has been determined. The sensitivity of PALS to metal overlayer interdiffusion is demonstrated. PALS is a non-destructive, depth profiling technique with the only requirement that positrons can be implanted into the porous film where Ps can form.

Sol-Gel Processing of Low Dielectric Constant Nanoporous Silica Thin Films

2001 ◽  
Vol 703 ◽  
Author(s):  
Deok-Yang Kim ◽  
Henry Du ◽  
Suhas Bhandarkar ◽  
David W. Johnson
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Average Pore Size ◽  
Sol Gel ◽  
Porous Silica ◽  
Dielectric Constants ◽  
Gelling Agent ◽  
Porous Films ◽  
Average Pore

ABSTRACTTetramethyl ammonium silicate (TMAS) is known as a structuring agent in zeolite synthesis. We report its first use to prepare porous silica films for low k dielectric applications in microelectronics. A solution of TMAS 18.7 wt. % was spin coated on silicon substrates with a 3000 Å thick thermal oxide. The spin coated films were subsequently heat-treated at 450°C to obtain porous silica. The use of TMAS solution without gelation led to films of only moderate porosity value of 10%. The addition of methyl lactate, a gelling agent, significantly increased film porosity and improved the pore size distribution. For example, 50% porosity and uniform pore size distribution (average pore size ∼ 40 Å) has been achieved. Dielectric constants (k) of our porous films are as low as 2.5.

scholarly journals Filtration performance and pore size distribution of hypochlorite aged PES/PVP ultrafiltration membranes

2015 ◽  
Vol 474 ◽  
pp. 175-186 ◽  
Author(s):  
Bastien Pellegrin ◽  
Fernanda Mezzari ◽  
Yamina Hanafi ◽  
Anthony Szymczyk ◽  
Jean-Christophe Remigy ◽  
...  
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Ultrafiltration Membranes ◽  
Filtration Performance

Improved design and protocol for evapoporometry determination of the pore-size distribution

2015 ◽  
Vol 496 ◽  
pp. 334-343 ◽  
Author(s):  
Ebrahim Akhondi ◽  
Farhad Zamani ◽  
Jia Wei Chew ◽  
William B. Krantz ◽  
Anthony G. Fane
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Improved Design
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