scholarly journals Comparison of Nitrogen Adsorption and Mercury Penetration Results: II. Pore size Distributions Calculated from Type IV Isotherm Data

1988 ◽  
Vol 5 (3) ◽  
pp. 168-190 ◽  
Author(s):  
Bruce D. Adkins ◽  
Burtron H. Davis
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Nitrogen Adsorption ◽  
Type Iv ◽  
Pore Size Distributions ◽  
Nitrogen Desorption ◽  
The Difference ◽  
Penetration Data ◽  
Packed Sphere

The pore distributions calculated from nitrogen desorption and from mercury penetration data are similar for the four materials utilized in this study. While there are small differences in the distributions calculated using different models (Cohan. Foster or Broekhoff-deBoer) with nitrogen adsorption or desorption isotherm data, all three show reasonable agreement with distributions calculated from mercury penetration data. Frequently practical catalysts have such a broad pore size distribution that neither method alone is adequate to measure the total pore size range. The present results suggest a direct comparison, without recourse to a scaling factor, is appropriate when comparing results from the two methods even though the pore size distribution maximum may vary by at least 50% depending upon the model chosen for the calculation. Better agreement may be obtained between the two experimental techniques by adjusting either the nitrogen adsorption data using a packed sphere model or the mercury penetration data by an earlier reported correction ratio. The difference between the two methods becomes less than 20% when a correction procedure is used; however, further studies are needed to define the range of material shaped that these procedures are applicable to.

scholarly journals Experimental investigation on pore size distribution and drying kinetics during lyophilization of sugar solutions

2018 ◽  
Author(s):  
Petra Foerst ◽  
M. Lechner ◽  
N. Vorhauer ◽  
H. Schuchmann ◽  
E. Tsotsas
Keyword(s):  
Pore Structure ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Freeze Drying ◽  
Three Dimensional ◽  
Drying Kinetics ◽  
Process Efficiency ◽  
Freeze Dried ◽  
Pore Size Distributions

The pore structure is a decisive factor for the process efficiency and product quality of freeze dried products. In this work the two-dimensional ice crystal structure was investigated for maltodextrin solutions with different concentrations by a freeze drying microscope. The resulting drying kinetics was investigated for different pore structures. Additionally the three-dimensional pore structure of the freeze dried samples was measured by µ-computed tomography and the pore size distribution was quantified by image analysis techniques. The two- and three-dimensional pore size distributions were compared and linked to the drying kinetics.Keywords: pore size distribution; freeze drying; maltodextrin solution; freeze drying microscope   

scholarly journals Ink-bottle Effect and Pore Size Distribution of Cementitious Materials Identified by Pressurization–Depressurization Cycling Mercury Intrusion Porosimetry

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1454 ◽  
Author(s):  
Yong Zhang ◽  
Bin Yang ◽  
Zhengxian Yang ◽  
Guang Ye
Keyword(s):  
Pore Structure ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Mercury Intrusion Porosimetry ◽  
Cementitious Materials ◽  
Limestone Powder ◽  
Accurate Estimation ◽  
Mercury Intrusion ◽  
Pore Size Distributions

Capturing the long-term performance of concrete must be underpinned by a detailed understanding of the pore structure. Mercury intrusion porosimetry (MIP) is a widely used technique for pore structure characterization. However, it has been proven inappropriate to measure the pore size distribution of cementitious materials due to the ink-bottle effect. MIP with cyclic pressurization–depressurization can overcome the ink-bottle effect and enables a distinction between large (ink-bottle) pores and small (throat) pores. In this paper, pressurization–depressurization cycling mercury intrusion porosimetry (PDC-MIP) is adopted to characterize the pore structure in a range of cementitious pastes cured from 28 to 370 days. The results indicate that PDC-MIP provides a more accurate estimation of the pore size distribution in cementitious pastes than the standard MIP. Bimodal pore size distributions can be obtained by performing PDC-MIP measurements on cementitious pastes, regardless of the age. Water–binder ratio, fly ash and limestone powder have considerable influences on the formation of capillary pores ranging from 0.01 to 0.5 µm.

The Effect of Fabric Weave Structure and Component Ratio on Pore Size Distribution

2011 ◽  
Vol 314-316 ◽  
pp. 1537-1541
Author(s):  
Jian Feng Di ◽  
Xiao Xia He ◽  
Hong Jin Qi ◽  
Wen Qin Du
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Cotton Fabric ◽  
Capillary Condensation ◽  
Polyester Fabric ◽  
Component Ratio ◽  
Weave Structure ◽  
Weave Fabric ◽  
The Difference

In order to provide the wetting processing and the design of thermal moisture comfort of fabric with micron-scaled pore size data, this paper reports on an experimental investigation on the pore size distribution of 6 kinds of fabrics with the method of seft-proposed weight-classification method. This paper focuses on the effect of fabric structure and component on the pore size distribution . Histograms reveal the relationship between various factors. For cotton fabric, the peak area of the histogram of 1/2 twill weave fabric (TWF) is wider and higher than that of plain weave fabric (PWF) due to fewer structure points and more loose structure. This leads to wicking rate increase. For the polyester fabric, the difference between the peak area shapes of the TWF and PWF is not obvious. This may arise from that smaller warp/weft density of both the samples inhibited by the change in inter-yarn gap leading to the similarity. For polyester-cotton fabric, with the increase in the ratio of hydrophilic cotton component, pore size range significantly expanded, showing more uniform wicking and capillary condensation.

scholarly journals Prediction of soil water retention properties using pore-size distribution and porosity

2013 ◽  
Vol 50 (4) ◽  
pp. 435-450 ◽  
Author(s):  
Christopher T.S. Beckett ◽  
Charles E. Augarde
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Soil Water ◽  
Water Retention ◽  
Adsorbed Water ◽  
Retention Data ◽  
Soil Water Retention ◽  
Pore Size Distributions ◽  
Water Retention Properties

Several models have been suggested to link a soil's pore-size distribution to its retention properties. This paper presents a method that builds on previous techniques by incorporating porosity and particles of different sizes, shapes, and separation distances to predict soil water retention properties. Mechanisms are suggested for the determination of both the main drying and wetting paths, which incorporate an adsorbed water phase and retention hysteresis. Predicted results are then compared with measured retention data to validate the model and to provide a foundation for discussing the validity and limitations of using pore-size distributions to predict retention properties.

scholarly journals Comparison of Nitrogen Adsorption and Mercury Penetration Results. Pore Size Distributions for a Series of Mo-A12O3 Catalysis with Increasing MoO3 Content

1987 ◽  
Vol 4 (1-2) ◽  
pp. 87-104 ◽  
Author(s):  
Bruce D Adkins ◽  
Jill B. Heink ◽  
Burtron H. Davis
Keyword(s):  
Pore Size ◽  
Surface Area ◽  
Three Dimensional ◽  
Nitrogen Adsorption ◽  
Bet Surface Area ◽  
Size Distributions ◽  
Electron Microscopic ◽  
Pore Size Distributions ◽  
Electron Microscopic Data ◽  
Penetration Data

Scanning electron microscopic data, X-ray diffraction patterns and porosity measurements are consistent with a structure for an Mo-A12O3 catalyst series containing a single surface layer of Mo up to the point where the Mo loadings exceed the amount required for a monolayer. For greater Mo loadings than required for a monolayer, three dimensional orthorhombic MoO3 is also present. The cumulative pore volume, on an alumina basis, does not appear to be significantly altered by MoO3 loadings up to about 15 wt.%. The BET surface area, on an alumina basis, remains constant with Mo loading. However, the apparent surface area calculated from mercury penetration data decreases with Mo loading. For these materials with cylindrical pores, the Broekhoff-deBoer model for the calculation of pore size distributions produced closer agreement to the mercury penetration pore size distribution. This is in contrast to materials composed of nonporous spheres where the Broekhoff-deBoer model provided poorer agreement to mercury penetration results than either the Cohan or a packed sphere model. The results show that, within a factor of two the pore size distributions calculated from nitrogen adsorption and mercury penetration data are comparable.

Two sides of the same inverse problem, in identifying the pore size distribution based on experiments with non-Newtonian fluids

2021 ◽  
Author(s):  
Martin Lanzendörfer
Keyword(s):  
Inverse Problem ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Forward Problem ◽  
Size Distributions ◽  
Pore Sizes ◽  
Pore Size Distributions ◽  
Flow Through ◽  
Effective Pore Size

<p>Following the capillary bundle concept, i.e. idealizing the flow in a saturated porous media in a given direction as the Hagen-Poiseuille flow through a number of tubular capillaries, one can very easily solve what we would call the <em>forward problem</em>: Given the number and geometry of the capillaries (in particular, given the pore size distribution), the rheology of the fluid and the hydraulic gradient, to determine the resulting flux. With a Newtonian fluid, the flux would follow the linear Darcy law and the porous media would then be represented by one constant only (the permeability), while materials with very different pore size distributions can have identical permeability. With a non-Newtonian fluid, however, the flux resulting from the forward problem (while still easy to solve) depends in a more complicated nonlinear way upon the pore sizes. This has allowed researchers to try to solve the much more complicated <em>inverse problem</em>: Given the fluxes corresponding to a set of non-Newtonian rheologies and/or hydraulic gradients, to identify the geometry of the capillaries (say, the effective pore size distribution).</p><p>The potential applications are many. However, the inverse problem is, as they usually are, much more complicated. We will try to comment on some of the challenges that hinder our way forward. Some sets of experimental data may not reveal any information about the pore sizes. Some data may lead to numerically ill-posed problems. Different effective pore size distributions correspond to the same data set. Some resulting pore sizes may be misleading. We do not know how the measurement error affects the inverse problem results. How to plan an optimal set of experiments? Not speaking about the important question, how are the observed effective pore sizes related to other notions of pore size distribution.</p><p>All of the above issues can be addressed (at least initially) with artificial data, obtained e.g. by solving the forward problem numerically or by computing the flow through other idealized pore geometries. Apart from illustrating the above issues, we focus on <em>two distinct aspects of the inverse problem</em>, that should be regarded separately. First: given the forward problem with <em>N</em> distinct pore sizes, how do different algorithms and/or different sets of experiments perform in identifying them? Second: given the forward problem with a smooth continuous pore size distribution (or, with the number of pore sizes greater than <em>N</em>), how should an optimal representation by <em>N</em> effective pore sizes be defined, regardless of the method necessary to find them?</p>

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