Effects of Calcium Ion in Highly Alkaline Plume on Permeability Change of Flow-Path

2006 ◽  
Vol 932 ◽  
Author(s):  
Hideo Usui ◽  
Yuichi Niibori ◽  
Koichi Tanaka ◽  
Osamu Tochiyama ◽  
Hitoshi Mimura
Keyword(s):  
Early Stage ◽  
Pure Water ◽  
Particle Surface ◽  
Packed Bed ◽  
Feed Solution ◽  
Emission Spectrometry ◽  
Precipitation Reaction ◽  
Permeability Change ◽  
Sem Images ◽  
Flow Paths

ABSTRACTFor the construction of the geological disposal system of radioactive wastes, a large amount of cement is used. Such a material alters the pH of groundwater to highly alkaline region [1-3]. The highly alkaline plume contains rich Ca ion compared to the surrounding environment, and the Ca ions reacts with soluble silicic acid. Its product would deposit on the surface of flow-paths in the natural barrier and decrease the permeability. In this study, the influence of Ca ion in highly alkaline plume on flow-paths has been examined by using packed bed column.The column was packed with the amorphous silica particles of 75-150 μm in diameter. The Ca(OH)2 solution (0.78 mM, 4.37 mM, and 8.48 mM, pH:12.2∼12.3) was continuously injected into the column at constant flow rate (1.1 mm/s), and the change of permeability was continuously monitored. At the same time, [Ca]total and [Si] in the eluted solution was measured by the inductively coupled plasma atomic emission spectrometry (ICP-AES). The Ca(OH)2 solutions were prepared with CO2-free pure water, and filtrated through 0.22 μm and 0.45 μm filter. The permeability was normalized by the initial permeability value.The experimental results showed that the permeability change and the chemical reactions in the packed bed depended on the concentration of Ca(OH)2 in the feed solution. The SEM images showed that the feed solution of 8.48 mM in [Ca]total apparently altered the particle surface with the products with Ca (deposition). Moreover, from the distribution of Ca on the cross section of packed particle (by EPMA), it was found that Ca deposited also in the inner pores of the particle. These results suggest that the deposition does not always change the permeability in the early stage of precipitation reaction. In the eluted solution, the concentrations of Ca and Si dramatically changed, depending on the concentration of Ca in the feed solution.

Fundamental Experiments on Permeability Change of Flow-path by Highly Alkaline Plume

2004 ◽  
Vol 824 ◽  
Author(s):  
Hideo Usui ◽  
Yuichi Niibori ◽  
Koichi Tanaka ◽  
Osamu Tochiyama ◽  
Hitoshi Mimura
Keyword(s):  
Flow Rate ◽  
Flow Direction ◽  
Particle Surface ◽  
Reliable Estimate ◽  
Sem Images ◽  
Flow Paths ◽  
Constant Flow Rate ◽  
Ph Values ◽  
Naoh Solution ◽  
The Difference

AbstractIn the geological disposal system, natural barrier contains many selective flow-paths. Since cement used for the repository construction alters the condition of groundwater to a highly alkaline pH of about 13, such hyperalkaline plume would affect permeabilities of the flow-paths. To obtain more reliable estimate on the migration of radionuclides released from the repository, we must consider the changes in flow-paths with time and/or in space.In this study, the influence of highly alkaline plume on the permeability has been examined, considering also the direction of flow. In order to simulate the flow-paths, the amorphous silica particles were packed in the column, and the NaOH solution (0.1 M) was injected continuously at a constant flow-rate into the column at room temperature. The change in the permeability was traced, and the concentration of silicic acid in the eluted solution was measured by using the silicomolybdenum-yellow method. It was confirmed that the difference of pH values at the inlet and outlet of the column was negligibly small (pH=13.0).The experimental results showed that the change in fraction dissolved with time strongly depended on a flow-rate and a flow-direction. However, in the relation between the permeability and the fraction dissolved, the permeability did not change in the range of up to 0.35 in fraction dissolved. The SEM images of particle surface showed that the inner pores of particle increased in size. This suggested that, in this range of fraction dissolved, the porosity between particles is almost retained, while each particle dissolves mainly through its inner pores. Moreover, the dissolution rate in the column flow system was considered as being remarkably limited by diffusion process, in comparison with that estimated from the batch test.

scholarly journals On the contribution of Aitken mode particles to cloud droplet populations at continental background areas – a parametric sensitivity study

2007 ◽  
Vol 7 (3) ◽  
pp. 6077-6112
Author(s):  
T. Anttila ◽  
V.-M. Kerminen
Keyword(s):  
Surface Tension ◽  
Particle Size ◽  
Chemical Composition ◽  
Pure Water ◽  
Particle Surface ◽  
Chemical Properties ◽  
Sensitivity Study ◽  
Geometric Standard Deviation ◽  
Cloud Droplets ◽  
Aitken Mode

Abstract. Aitken mode particles are potentially an important source of cloud droplets in continental background areas. In order to find out which physico-chemical properties of Aitken mode particles are most important regarding their cloud-nucleating ability, we applied a global sensitivity method to an adiabatic air parcel model simulating the number of cloud droplets formed on Aitken mode particles, CD2. The technique propagates uncertainties in the parameters describing the properties of Aitken mode to CD2. The results show that if the Aitken mode particles do not contain molecules that are able to reduce the particle surface tension more than 30% and/or decrease the mass accommodation coefficient of water, α, below 10−2, the chemical composition and modal properties may have roughly an equal importance at low updraft velocities characterized by maximum supersaturations <0.1%. For larger updraft velocities, however, the particle size distribution is clearly more important than the chemical composition. In general, CD2 exhibits largest sensitivity to the particle number concentration, followed by the particle size. Also the shape of the particle mode, characterized by the geometric standard deviation (GSD), can be as important as the mode mean size at low updraft velocities. Finally, the performed sensitivity analysis revealed also that the chemistry may dominate the total sensitivity of CD2 to the considered parameters if: 1) the value of α varies at least one order of magnitude more than what is expected for pure water surfaces (10−2–1), or 2) the particle surface tension varies more than roughly 30% under conditions close to reaching supersaturation.

scholarly journals Fabrication and Performance Evaluation of Integrated Solar-Driven Membrane Distillation System with Serpentine-shape of Flat Plate Solar Collector for Seawater Desalination

2019 ◽  
Vol 23 (3) ◽  
Author(s):  
M. A. H. M. Hanoin ◽  
N. S. Mohammed ◽  
M. A. I. Z. Arris ◽  
A. I. A. Bakar ◽  
N. M. Mokhtar ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
Flat Plate ◽  
Solar Collector ◽  
Pure Water ◽  
Feed Solution ◽  
Membrane Distillation ◽  
The Self ◽  
Permeate Flux ◽  
Salt Rejection ◽  
Flat Plate Solar Collector

Solar-powered membrane distillation (SPMD) system has gained its popularity in desalination application for past decade credit to the system efficiency in producing pure water and the utilization of renewable energy. However, most of the past SPMD works used commercial solar thermal collector (STC) as the thermal energy supply to the feed solution and the study only focused on the performance of the system in terms of flux and salt rejection. In this work, a self-made flat plate solar collector (FPSC) with the serpentine-shape pipe was designed and fabricated to study the effect of the STC towards the membrane performance. Before testing, a simulation work of the fluid flow inside the serpentine-shape pipe of the FPSC was analyzed using NX 10.0 computer-aided design simulation. After that, the efficiency of the self-made FPSC system was tested directly to sunlight in order to identify the maximum irradiance and the temperature of the feed solution. Due to the fluctuation of solar irradiance, the experimental setup of the SPMD system was tested using a solar simulator, and the performance was compared with the membrane distillation (MD) system without integration with FPSC system. Based on the simulation data, it can be concluded that the heat losses across the pipe are due to the slower fluid velocity and sudden pressure drop, which attributed to centripetal force and pressure differences. Meanwhile, the outdoor evaluation data showed that the temperatures of collector and water inside the feed tank could reach up to 84°C and 64°C, respectively when the maximum irradiance of 938 W/m2 was applied. For the performance evaluation between with and without the self-made FPSC system, it can be seen that only marginal difference can be observed for the permeate flux and salt rejection with an average difference of 6.06% and 1.29%, respectively.

Interlamellar Incorporation of Charged Polymer Nanobeads into Sodium Montmorillonite

2004 ◽  
Vol 847 ◽  
Author(s):  
Svetlana Khvan ◽  
Sang-Soo Lee ◽  
Junkyung Kim
Keyword(s):  
Polymer Matrix ◽  
Surface Characterization ◽  
Particle Surface ◽  
Polymer Particle ◽  
Polymer Chains ◽  
Sem Images ◽  
Tof Sims ◽  
Strong Adhesion ◽  
Density Surface ◽  
Cationic Exchange

ABSTRACTComplete delamination of clay in polymer matrix has been strongly prohibited due to strong adhesion of guest polymer chains between hydrophilic clay as well as degradation and desorption of organic materials in the gallery at high temperature. Incorporation of charged nanosized polystyrene beads directly into the gallery of pristine clay through exfoliation-exchange mechanism has been proposed to overcome the drawbacks.Synthesis of polymer nanobeads via emulsifier-free emulsion polymerization allowed to achieving formation of particles of appropriate particle size and surface charge density. Surface characterization, performed with XPS and ToF SIMS, has provided the results on the existence and the nature of the functional groups on the polymer particle surface, which have been found to be in a good compliance.Morphology of polymer-incorporated clay was observed from TEM, FE-SEM images. Study on mechanism of incorporation via XRD, XPS, ToF-SIMS suggested that adsorption of polymer nanobeads through cationic exchange of intergallery cation of clay for onium ion at the surface of polymer nanobead not only improves compatibility of clay with polymer matrix, but, what is essential, dramatically promotes expansion of clay gallery.

scholarly journals The Temple of Apollo at Delphi

1888 ◽  
Vol 9 ◽  
pp. 282-322 ◽  
Author(s):  
J. Henry Middleton
Keyword(s):  
Early Stage ◽  
Pure Water ◽  
Stage Of Development ◽  
The Earth ◽  
The Mind ◽  
The Temple

In many respects Delphi and its varied cults possess an interest which is not to be rivalled by that of any other Hellenic site. The lofty precipices, the dark deeply-cleft ravines, the mysterious caves, and the bubbling springs of pure water, combine to give the place a romantic charm and a fearfulness of aspect which no description can adequately depict.Again Delphi stands alone in the catholic multiplicity of the different cults which were there combined.In primitive times it was the awfulness of Nature which impressed itself on the imaginations of the inhabitants.In an early stage of development the mind of man tends to gloomy forms of religion: his ignorance and comparative helplessness tend to fill his brain with spiritual terrors and forebodings. Thus at Delphi the primitive worship was that of the gloomy Earth and her children, the chasm-rending Poseidon, and the Chthonian Dionysus, who, like Osiris, was the victim of the evil powers of Nature. It was not till later times that the bright Phoebus Apollo came to Delphi to slay the earth-born Python, just as the rising sun dissipates the shadows in the depths of the Delphian ravines, or as in the Indian legend the god Indra kills with his bright arrows the great serpent Ahi—symbol of the black thunder-cloud.

scholarly journals Fabrication of a novel cyanoethyl cellulose substrate for thin-film composite forward osmosis membrane

2019 ◽  
Vol 1 (1) ◽  
pp. 18-32 ◽  
Author(s):  
Ke Zheng ◽  
Shaoqi Zhou
Keyword(s):  
Thin Film ◽  
Water Flux ◽  
Forward Osmosis ◽  
Feed Solution ◽  
Salt Flux ◽  
Sem Images ◽  
Film Composite ◽  
Thin Film Composite ◽  
Reverse Salt Flux ◽  
Cyanoethyl Cellulose

Abstract In this study, cyanoethyl cellulose (CEC) was used as a membrane material, and polyvinylpyrrolidone (PVP) was used as pore-forming agent to prepare the substrates for the thin-film composite (TFC) forward osmosis (FO) membrane for the first time. The experimental results demonstrate that the properties of the substrates were significantly improved after PVP was added. The scanning electron microscope (SEM) images show that a two-sublayer structure, a fringe-like top sublayer and macrovoids with sponge-like wall bottom sublayer, were formed after the addition of PVP. These improvements contributed to improved membrane performance during FO tests. Meanwhile, after adding PVP, the TFC membranes exhibited good water flux, and excellent specific reverse salt flux. For instance, the TFC-M2 exhibited 9.10/20.67 LMH water flux, 1.35/2.24 gMH reverse salt flux, and 0.15/0.11 g/L specific reverse salt flux in FO/pressure-retarded osmosis mode while using 1 M NaCl as the draw solution and deionized (DI) water as the feed solution.

scholarly journals Effect of Kenaf MCC composition on Thin Film Composite membrane for NaCI Rejection

2019 ◽  
Vol 258 ◽  
pp. 04003
Author(s):  
Azman Ismail ◽  
Ramlah Mohd Tajuddin ◽  
Hamizah Mohktar ◽  
Ahmad Fauzi Ismail
Keyword(s):  
Thin Film ◽  
Interfacial Polymerization ◽  
Pure Water ◽  
Water Flux ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Sem Images ◽  
Water Contact ◽  
Membrane Performance ◽  
Pure Water Flux

A modified thin film PSf-MCC reverse osmosis membrane was prepared by interfacial polymerization between aqueous MPD and TMC as the organic monomer. Aim of this study is to determine the effect of MCC in membrane formulation and fabrication. The surface and cross section morphology of TFC PSF/MCC membrane shows MCC particle which able to improve hydrophilicity of the membrane. The SEM images showed dense and porous structure of the MCC incorporated membranes. In addition, the water contact angle measurement also confirmed the increased hydrophilicity of the modified membranes. The effect of MCC on membrane matric influence the membrane performance in terms of NaCl rejection and pure water flux. Results showed that TFC PSf/MCC membrane shows NaCl rejection up to 98.9% compared with TFC PSf membrane. TFC PSf/MCC membrane also showed the highest pure water flux which is 3.712 Lm2/hr compare with TFC PSF membrane which is 3.606 Lm2/hr. The overall result proved that MCC particle could improve membrane hydrophilicity hence, increased pure water flux and salt rejection.

Preparation of Silica/Polymer Hybrid Nanoparticles via a Semi-Continuous Soup-Free Emulsion Polymerization

2015 ◽  
Vol 1120-1121 ◽  
pp. 233-242
Author(s):  
Joshua Qing Song Li ◽  
Hai Wang ◽  
Yan Qiu Wang
Keyword(s):  
Emulsion Polymerization ◽  
Early Stage ◽  
Size Exclusion ◽  
Hybrid Nanoparticles ◽  
Core Shell ◽  
Particle Coagulation ◽  
Shell Nanoparticles ◽  
Sem Images ◽  
Spectra Analysis ◽  
Polymer Hybrid

Hybrid nanoparticles were prepared by direct polymerization of methyl methacrylate, vinyl acetate, and styrene monomers onto the unmodified hydrophilic surfaces of 33 nm silica nanoparticles in a semi-continuous soap-free emulsion polymerization at a monomer starved condition. The polymerization was initiated by potassium persulfate with constant monomer feed at 0.01, 0.02, or 0.04 mL/min. The growth of the core-shell nanoparticles were measured by a laser particle size analyzer. FT-IR spectra analysis confirmed the hybrid structures of the synthesized nanoparticles. SEM images and size exclusion chromatography (SEC) results indicated regular core-shell microsphere structures. The hybrid nanoparticles increased in monodispersity and size over 100 nm with the reaction. However, SiO2/polystyrene (PS) nanoparticles grew much faster compared with SiO2/polymethyl methacrylate (PMMA) and SiO2/polyvinyl acetate (PVAC). There was particle coagulation, about 12 SiO2/PS particles aggregating to one, in the early stage of the seeded process. In addition, PS secondary particles were formed before the particle coagulation, and then merged with the SiO2/PS nanoparticles in the particle coagulation. The formation of SiO2/polymer hybrid nanoparticles depended on the hydrophilic characteristics of the polymer, and the size of silica seeds.

A Double Porosity Model to Describe Both Permeability Change and Dissolution Processes

2014 ◽  
Author(s):  
Yuichi Niibori ◽  
Hideo Usui ◽  
Taiji Chida ◽  
Hitoshi Mimura
Keyword(s):  
Size Fraction ◽  
Packed Bed ◽  
Double Porosity ◽  
Experimental Result ◽  
Permeability Change ◽  
Small Particles ◽  
Size Change ◽  
Simple Diffusion ◽  
Packed Particle ◽  
Natural Barrier

Cement is a practical material for constructing the geological disposal system of radioactive wastes. However, such materials alter groundwater up to 13 in pH around the repository, changing the permeability of natural barrier. So far, the authors have examined the relation of permeability change with dissolution process by flowing a high pH solution (NaOH, 0.1 mM) into a bed packed with amorphous silica particles. Here, the particle diameters were adjusted to a size fraction of 74 to 149 μm by sieving. Its specific surface area was estimated as 350 m2/g by the BET method using nitrogen gas. The experimental results showed that the permeability did not immediately change although the soluble silicic acid continuously flowed out of the packed bed. This study proposes a new mathematical model considering the diffusion and dissolution processes in the inner pore of the particle. This model assumed that each packed particle (74 to 149μm in diameter) consists of the sphere-shaped aggregation of smaller particles (20 nm in diameter). OH− ions diffuse into the pore between such small particles, and simultaneously consumed by the reaction with small particles. The radius of the each packed particle (sphere-shaped aggregation of small particles) was defined by the length from the center of the aggregation to the region where the small particles still remains. Since the outer small particles more easily dissolve than inner small particles because of diffusion process of OH− ions, each packed particle gradually shrinks. The fundamental equations consist of a simple diffusion equation of spherical coordinates of OH− ions considering the reaction term, which is linked by the equation to describe the size change of small particles with time. Here, this model also considered a change (time and space) of the diffusion oefficient caused by the change of the porosity between small particles. Besides, the change of over-all permeability of the packed bed was evaluated by Kozeny-Carman equation and the calculated radii of packed particles. The dissolution rate constant already reported was used. The calculated result was able to well describe the experimental result, though there was no fitting parameter in the comparison with the experiment results. While the flow paths of underground cannot be simply simulated by a packed bed, this approach suggested that the dynamic behavior of permeability in a natural barrier depends also on non-uniformity of dissolution processes in inner pores (secondary pores) of minerals.

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