A Study of a New Ceramic Membrane for Use in Hemodialysis

2004 ◽  
Author(s):  
Zhongping Huang ◽  
Weiming Zhang ◽  
Sonja M. Tang ◽  
Jianping Yu ◽  
Stephen J. Lai-Fook ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Hydraulic Conductivity ◽  
Oxalic Acid ◽  
Pore Structure ◽  
Pore Size ◽  
Ceramic Membrane ◽  
Anodic Alumina ◽  
Pore Distribution ◽  
Self Organized ◽  
Hemodialysis Membrane

The non-uniformity of pore size and pore distribution of the current hemodialysis membrane results in low efficiency of uremic solute removal as well as the loss of albumin. By using nano technology, an anodic alumina membrane (ceramic membrane) with self-organized nano-pore structure was produced. The objective of this study was to investigate the correlation between various anodization conditions and the pore characteristics of the ceramic membrane as a potential use in artificial kidney / hemodialysis. An aluminum thin film was oxidized in two electrolytes consisting of 3% and 5% sulfuric acid and 2.7% oxalic acid. The applied voltages were 12.5, 15, 17.5 and 20 (V) for sulfuric acid and 20, 30, 40 and 50 (V) for oxalic acid. Pore size and porosity were determined by analyzing scanning electron microscopy (SEM) images and hydraulic conductivity was measured. Pore size increased linearly with voltage. Acid concentration affected pore formation but not pore size and pore distribution. Hydraulic conductivity of the ceramic membrane was higher than that of polymer dialysis membrane. The optimal formation conditions for self-organized nano-pore structure of ceramic membrane were 12.5–17.5V in 3–5% sulfuric acid at 0 °C. These conditions produced ceramic membranes with pores of ~ 10 nm diameter. Conclusion: Anodic alumina technology reliably produced in quantity structures with pore sizes in the 10–50 nm diameter range. Because of more uniform pore size, high porosity, high hydraulic conductivity and resistance to high temperature, the ceramic membrane has potential for future application as a hemodialysis membrane.

Nanoporous Alumina Membranes for Enhancing Hemodialysis

2006 ◽  
Vol 1 (1) ◽  
pp. 79-83 ◽  
Author(s):  
Zhongping Huang ◽  
Weiming Zhang ◽  
Jianping Yu ◽  
Dayong Gao
Keyword(s):  
Sulfuric Acid ◽  
Hydraulic Conductivity ◽  
Oxalic Acid ◽  
Pore Size ◽  
Ceramic Membrane ◽  
Ceramic Membranes ◽  
Alumina Membranes ◽  
Self Organized ◽  
Nanopore Structure ◽  
Hemodialysis Membrane

The nonuniformity of pore size and pore distribution of the current hemodialysis membrane results in low efficiency of uremic solute removal as well as the loss of albumin. By using nanotechnology, an anodic alumina membrane (ceramic membrane) with self-organized nanopore structure was produced. The objective of this study was to fabricate nanoporous alumina membranes and investigate the correlation between various anodization conditions and the pore characteristics in order to find its potential application in artificial kidney/hemodialysis. An aluminum thin film was oxidized in two electrolytes consisting of 3% and 5% sulfuric acid and 2.7% oxalic acid. The applied voltages were 12.5, 15, 17.5, and 20V for sulfuric acid and 20, 30, 40, and 50V for oxalic acid. Pore size and porosity were determined by analyzing Scanning Electron Microscopy (SEM) images and hydraulic conductivity was measured. Results show that pore size increased linearly with voltage. Acid concentration affected pore formation but not pore size and pore distribution. Hydraulic conductivity of the ceramic membrane was higher than that of the polymer dialysis membrane. The optimal formation conditions for self-organized nanopore structure of the ceramic membrane were 12.5-17.5V in 3–5% sulfuric acid at 0°C. Under these conditions, ceramic membranes with pores size of ∼10nm diameter can be produced. In conclusion, we used anodic alumina technology to reliably produce in quantity ceramic membranes with a pore diameter of 10-50nm. Because of more uniform pore size, high porosity, high hydraulic conductivity, and resistance to high temperature, the ceramic membrane has the potential application as a hemodialysis membrane.

scholarly journals Examining the effect of pore size distribution and shape on flow through unsaturated peat using computed tomography

2009 ◽  
Vol 13 (10) ◽  
pp. 1993-2002 ◽  
Author(s):  
F. Rezanezhad ◽  
W. L. Quinton ◽  
J. S. Price ◽  
D. Elrick ◽  
T. R. Elliot ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Hydraulic Conductivity ◽  
Pore Structure ◽  
Pore Size ◽  
Soil Water ◽  
Water Pressure ◽  
Peat Soil ◽  
Pressure Head ◽  
Peat Soils ◽  
Unsaturated Hydraulic Conductivity

Abstract. The hydraulic conductivity of unsaturated peat soil is controlled by the air-filled porosity, pore size and geometric distribution as well as other physical properties of peat materials. This study investigates how the size and shape of pores affects the flow of water through peat soils. In this study we used X-ray Computed Tomography (CT), at 45 μm resolution under 5 specific soil-water pressure head levels to provide 3-D, high-resolution images that were used to detect the inner pore structure of peat samples under a changing water regime. Pore structure and configuration were found to be irregular, which affected the rate of water transmission through peat soils. The 3-D analysis suggested that pore distribution is dominated by a single large pore-space. At low pressure head, this single large air-filled pore imparted a more effective flowpath compared to smaller pores. Smaller pores were disconnected and the flowpath was more tortuous than in the single large air-filled pore, and their contribution to flow was negligible when the single large pore was active. We quantify the pore structure of peat soil that affects the hydraulic conductivity in the unsaturated condition, and demonstrate the validity of our estimation of peat unsaturated hydraulic conductivity by making a comparison with a standard permeameter-based method. Estimates of unsaturated hydraulic conductivities were made for the purpose of testing the sensitivity of pore shape and geometry parameters on the hydraulic properties of peats and how to evaluate the structure of the peat and its affects on parameterization. We also studied the ability to quantify these factors for different soil moisture contents in order to define how the factors controlling the shape coefficient vary with changes in soil water pressure head. The relation between measured and estimated unsaturated hydraulic conductivity at various heads shows that rapid initial drainage, that changes the air-filled pore properties, creates a sharp decline in hydraulic conductivity. This is because the large pores readily lose water, the peat rapidly becomes less conductive and the flow path among pores, more tortuous.

scholarly journals A Fractal Model of Hydraulic Conductivity for Saturated Frozen Soil

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 369 ◽  
Author(s):  
Lei Chen ◽  
Dongqing Li ◽  
Feng Ming ◽  
Xiangyang Shi ◽  
Xin Chen
Keyword(s):  
Hydraulic Conductivity ◽  
Pore Structure ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Fractal Theory ◽  
Frozen Soil ◽  
Soil Freezing ◽  
Size Dimension ◽  
Maximum Pore Size

In cold regions, hydraulic conductivity is a critical parameter for determining the water flow in frozen soil. Previous studies have shown that hydraulic conductivity hinges on the pore structure, which is often depicted as the pore size and porosity. However, these two parameters do not sufficiently represent the pore structure. To enhance the characterization ability of the pore structure, this study introduced fractal theory to investigate the influence of pore structure on hydraulic conductivity. In this study, the pores were conceptualized as a bundle of tortuous capillaries with different radii and the cumulative pore size distribution of the capillaries was considered to satisfy the fractal law. Using the Hagen-Poiseuille equation, a fractal capillary bundle model of hydraulic conductivity for saturated frozen soil was developed. The model validity was evaluated using experimental data and by comparison with previous models. The results showed that the model performed well for frozen soil. The model showed that hydraulic conductivity was related to the maximum pore size, pore size dimension, porosity and tortuosity. Of all these parameters, pore size played a key role in affecting hydraulic conductivity. The pore size dimension was found to decrease linearly with temperature, the maximum pore size decreased with temperature and the tortuosity increased with temperature. The model could be used to predict the hydraulic conductivity of frozen soil, revealing the mechanism of change in hydraulic conductivity with temperature. In addition, the pore size distribution was approximately estimated using the soil freezing curve, making this method could be an alternative to the mercury intrusion test, which has difficult maneuverability and high costs. Darcy’s law is valid in saturated frozen silt, clayed silt and clay, but may not be valid in saturated frozen sand and unsaturated frozen soil.

Effect of Concentration of Oxalic Acid on the Synthesis of Porous Anodic Alumina (PAA) on Aluminum Alloy AA6061

2016 ◽  
Vol 857 ◽  
pp. 281-285
Author(s):  
Chun Hong Voon ◽  
Bee Ying Lim ◽  
K.L. Foo ◽  
Uda Hashim ◽  
Sung Ting Sam ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Oxalic Acid ◽  
Pore Size ◽  
Anodic Alumina ◽  
Porous Anodic Alumina ◽  
Edx Analysis ◽  
Interpore Distance ◽  
Ordered Porous

In this study, porous anodic alumina was formed by anodizing of aluminum alloy AA6061 in oxalic acid with concentration ranged from 0.1 M to 1.0 M respectively. AA6061 alloys were anodized at 40 V and 25°C for 60 minutes. FESEM images show that the uniformity of the pores arrangement of porous anodic alumina depends significantly on the concentration of oxalic acid. Well-ordered porous anodic alumina was formed in oxalic acid of 0.3 M, 0.5 M and 0.7 M while disordered porous anodic alumina were formed when the oxalic acid of 0.1 M and 1.0 M were used as electrolytes. EDX analysis revealed that the only peaks corresponding to aluminum and oxygen were detected. Pore size was found to increase with the concentration of oxalic acid while the interpore distance remained almost unchanged although the concentration of oxalic acid increased from 0.1 M to 0.7 M. Atypical anodic alumina without pores arrangement was formed when 1.0 M oxalic acid was used for anodizing.

Characterization of Pore Structure of Hardened Cement-Asphalt Paste by Mercury Intrusion Porosimetry

2014 ◽  
Vol 1004-1005 ◽  
pp. 1589-1593 ◽  
Author(s):  
Sheng Zhang ◽  
Xi Ling Zhou ◽  
Ke Ren Zheng ◽  
You Jun Xie ◽  
Qiang Fu
Keyword(s):  
Pore Structure ◽  
Pore Size ◽  
Mercury Intrusion Porosimetry ◽  
Total Porosity ◽  
Pore Distribution ◽  
Hardened Cement ◽  
Volume Distribution ◽  
Mercury Intrusion ◽  
Two Peaks

To know the pore structure of cement-asphalt pastes, mercury intrusion porosimetry was applied to measure the total porosity, pore distribution and accumulative volume distribution of pore size and the pore structures were analyzed. The results show that the total porosities decline with increase in ages and reduction in A/C ratio. The total porosities declines from 28% at 1d, to 15.8%~17.2% at 28d; the most probable pore size declines from 20nm at 1d to 5nm at 28d.At 28d, there is an increase in the magnitude of pore size between100nm and 5μm; the volume faction of smaller than 5μm is 40~50%; and the amount of pore size smaller than 5nm account for 6%.There are two peaks (5μm & 50μm) in the curves of pore distribution.

The Synthesis and Characterization of Anodic Alumina Oxide Using Sulfuric Acid and Oxalic Acid

2021 ◽  
Vol 31 ◽  
pp. 35-44
Author(s):  
Nur Afieqah Md. Ghazazi ◽  
Syahida Suhaimi ◽  
Muhammad Zamir Othman
Keyword(s):  
Sulfuric Acid ◽  
Oxalic Acid ◽  
Morphological Structure ◽  
Anodic Alumina ◽  
Electrochemical Anodization ◽  
Anodic Alumina Oxide ◽  
Alumina Oxide ◽  
Average Size ◽  
Two Parameters

Anodic Alumina Oxide (AAO) is one of the nanomaterials that have developed as a template in the nanowires, nanodots and nanotubes. This research focuses on synthesizing AAO by two different electrolytic solutions which are using sulfuric acid (H2SO4) and oxalic acid (C2H2O4) by electrochemical anodization method. Two parameters were influencing the anodization process in the experiment; the type and the concentration of the electrolytic solution. The effects of the different type of electrolytic solutions produced different size of pores. When the voltage used is 25 V in H2SO4, the optimum reading size of the nanopores is in the range of 16-22 nm, whereas the AAO pores in C2H2O4 are in the range of 100-200 nm. Meanwhile, the concentration of H2SO4 and C2H2O4 is set to be 0.3 M, 0.4 M and 0.5 M., The results in 0.3 M H2SO4 and C2H2O4, show the optimum concentration of electrolytic solutions which is the key parameter affecting the morphological structure of porous membranes in AAO. The optimum value for these two acidic solutions has produced such highly ordered arrangement of nanopores which are from the average size of nanopores that anodized in sulfuric acid is 19 nm while 120 nm in oxalic acid. The morphological structure properties of AAO templates include the diameter of nanopores, the thickness of membrane and density of nanopores would be examined by Field Emission Scanning Electron Microscope (FESEM) and Energy Dispersive X-ray (EDX). Also, Fourier-transmittance infrared spectroscopy (FTIR) detected the chemical functional group of bonds in AAO. In conclusion, AAO templates have a big potential to be the major contributor in the future for the development of new electronic devices.

scholarly journals Examining the effect of pore size distribution and shape on flow through unsaturated peat using 3-D computed tomography

2009 ◽  
Vol 6 (3) ◽  
pp. 3835-3862 ◽  
Author(s):  
F. Rezanezhad ◽  
W. L. Quinton ◽  
J. S. Price ◽  
D. Elrick ◽  
T. R. Elliot ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Hydraulic Conductivity ◽  
Pore Structure ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Water Pressure ◽  
Pressure Head ◽  
Peat Soils ◽  
Unsaturated Hydraulic Conductivity

Abstract. The hydraulic conductivity of unsaturated peat soils is controlled by the peat structure which affects the air-filled porosity, pore size distribution and shape. This study investigates how the size and shape of pores affects the flow of water through peat soils. In this study we used X-ray Computed Tomography (CT), at 45 µm resolution under 5 specific soil-water pressure head levels to provide 3-D, high-resolution images that were used to detect the inner pore structure of peat samples under a changing water regime. Pore structure and configuration were found to be irregular, which affected the rate of water transmission through peat soils. The 3-D analysis suggested that pore distribution is dominated by a single large pore-space. At low pressure head, this single large air-filled pore imparted a more effective flowpath compared to smaller pores. Smaller pores were disconnected and the flowpath was more tortuous than in the single large air-filled pore, and their contribution to flow was negligible when the single large pore was active. We quantify the pore structure of peat soil that affects the hydraulic conductivity in the unsaturated condition, and demonstrate the validity of our estimation of peat unsaturated hydraulic conductivity by making a comparison with a standard permeameter-based method. Estimates of unsaturated hydraulic conductivities were made for the purpose of testing the sensitivity of pore shape and geometry parameters on the hydraulic properties of peats and how to evaluate the structure of the peat and its affects on parameterization. We also studied the ability to quantify these factors for different soil moisture contents in order to define how the factors controlling the shape coefficient vary with changes in soil water pressure head. The relation between measured and estimated unsaturated hydraulic conductivity at various heads shows that rapid initial drainage, that changes the air-filled pore properties, creates a sharp decline in hydraulic conductivity. This is because the large pores readily lose water, the peat rapidly becomes less conductive and the flow path among pores, more tortuous.

Application of the ceramic membrane with hydrophobic skin layer to separation of activated sludge

1997 ◽  
Vol 35 (8) ◽  
pp. 137-144 ◽  
Author(s):  
Tsuyoshi Nomura ◽  
Takao Fujii ◽  
Motoyuki Suzuki
Keyword(s):  
Activated Sludge ◽  
Pore Size ◽  
Ceramic Membrane ◽  
Membrane Separation ◽  
Porous Ceramic ◽  
Porous Membrane ◽  
Skin Layer ◽  
Gas Permeation ◽  
Wide Range ◽  
Cake Layer

Porous membrane of poly(tetrafluoroethylene) (PTFE) was formed on the surface of porous ceramic tubes by means of heat treatment of the PTFE particles deposit layer prepared by filtering PTFE microparticles emulsified in aqueous phase. By means of inert gas permeation, pore size was determined and compared with scanning electron micrograph observation. Also rejection measurement of aqueous dextran solutions of wide range of molecular weights showed consistent results regarding the pore size. Since the membrane prepared by this method is stable and has unique features derived from PTFE, it is expected that the membrane has interesting applications in the field of water treatment. Membrane separation of activated sludge by this composite membrane and original ceramics membrane showed that the PTFE membrane gives better detachability of the cake layer formed on the membrane. This might be due to the hydrophobic nature of the PTFE skin layer.

scholarly journals Construction of pore structure and lithology of digital rock physics based on laboratory experiments

2021 ◽  
Vol 11 (5) ◽  
pp. 2113-2125
Author(s):  
Chenzhi Huang ◽  
Xingde Zhang ◽  
Shuang Liu ◽  
Nianyin Li ◽  
Jia Kang ◽  
...  
Keyword(s):  
Pore Structure ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Laboratory Experiments ◽  
Rock Physics ◽  
Reconstruction Method ◽  
Digital Rock Physics ◽  
Digital Rock ◽  
The Core

AbstractThe development and stimulation of oil and gas fields are inseparable from the experimental analysis of reservoir rocks. Large number of experiments, poor reservoir properties and thin reservoir thickness will lead to insufficient number of cores, which restricts the experimental evaluation effect of cores. Digital rock physics (DRP) can solve these problems well. This paper presents a rapid, simple, and practical method to establish the pore structure and lithology of DRP based on laboratory experiments. First, a core is scanned by computed tomography (CT) scanning technology, and filtering back-projection reconstruction method is used to test the core visualization. Subsequently, three-dimensional median filtering technology is used to eliminate noise signals after scanning, and the maximum interclass variance method is used to segment the rock skeleton and pore. Based on X-ray diffraction technology, the distribution of minerals in the rock core is studied by combining the processed CT scan data. The core pore size distribution is analyzed by the mercury intrusion method, and the core pore size distribution with spatial correlation is constructed by the kriging interpolation method. Based on the analysis of the core particle-size distribution by the screening method, the shape of the rock particle is assumed to be a more practical irregular polyhedron; considering this shape and the mineral distribution, the DRP pore structure and lithology are finally established. The DRP porosity calculated by MATLAB software is 32.4%, and the core porosity measured in a nuclear magnetic resonance experiment is 29.9%; thus, the accuracy of the model is validated. Further, the method of simulating the process of physical and chemical changes by using the digital core is proposed for further study.

Self-organized formation of hexagonal pore arrays in anodic alumina

1998 ◽  
Vol 72 (10) ◽  
pp. 1173-1175 ◽  
Author(s):  
O. Jessensky ◽  
F. Müller ◽  
U. Gösele
Keyword(s):  
Anodic Alumina ◽  
Self Organized
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