The Influence of Groundwater on the Stability of Silica Colloids

2009 ◽  
Vol 1193 ◽  
Author(s):  
Pirkko Holtta ◽  
Mari Lahtinen ◽  
Martti Hakanen ◽  
Jukka Lehto ◽  
Piia Juhola
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Colloidal Silica ◽  
Silica Sol ◽  
Low Salinity ◽  
Silica Concentration ◽  
Silica Colloids ◽  
The Stability

AbstractNon-cementitious grouts have been tested in Olkiluoto for the sealing of fractures with the small hydraulic apertures. A promising non-cementitious inorganic grout material for sealing the fractures with the apertures less than 0.05 mm is commercial colloidal silica called silica sol. The potential relevance of colloid-mediated radionuclide transport is highly dependent on their stability in different geochemical environments. The objective of this work was to follow stability of silica sol colloids in low salinity Allard and saline OLSO reference groundwater (pH 7–11) and in deionized milliQ water. Stability of silica sol colloids was followed by measuring particle size distribution, zeta potential, colloidal and reactive silica concentrations. The particle size distributions were determined applying the dynamic light scattering (DLS) method and zeta potential based on dynamic electrophoretic mobility. The colloidal silica concentration was calculated from DLS measurements applying a calibration using a standard series of silica sol. Dissolved reactive silica concentration was determined using the molybdate blue (MoO4) method.These results confirmed that the stability of silica colloids dependent significantly on groundwater salinity. In deionized water, particle size distribution and zeta potential was rather stable except the most diluted solution. In low salinity Allard, particle size distribution was rather constant and the mean particle diameter remained less than 100 nm. High negative zeta potential values indicated the existence of stable silica colloids. In saline OLSO, particle size distribution was wide from a nanometer scale to thousands of nanometers. The disappearance of large particles, decrease in colloidal particle concentration and zeta potential near zero suggest flocculation or coagulation. Under prevailing saline groundwater conditions in Olkiluoto silica colloids released from silica sol are expected to be instable but the possible influence of low salinity glacial melt water has to be considered.

Effect of Ionic Strength on the Stability of Colloids Released from Injection Grout Silica Sol

2010 ◽  
Vol 1265 ◽  
Author(s):  
Pirkko L Holtta ◽  
Mari Lahtinen ◽  
Martti Hakanen ◽  
Jukka Lehto ◽  
Piia Juhola
Keyword(s):  
Particle Size ◽  
Ionic Strength ◽  
Zeta Potential ◽  
Silica Gel ◽  
Colloidal Silica ◽  
Particle Diameter ◽  
Silica Sol ◽  
Deionized Water ◽  
Silica Colloids ◽  
The Stability

AbstractIn Olkiluoto Finland colloidal silica called silica sol (EKA Chemicals) will be used as a non-cementitious grout for the sealing of fractures of the hydraulic apertures of 0.05 mm or less. The use of colloidal material has to be considered in the long-term safety assessment of a spent nuclear fuel repository. The potential relevance of colloid-mediated radionuclide transport is highly dependent on their stability in different geochemical environments. Objective of this work was to study the effect of ionic strength on stability of silica colloids released from silica gel. Silica gel samples were stored in contact with NaCl and CaCl2 electrolyte solutions and in deionized water. Colloid release and stability were followed for two years by taking the samples after one month and then twice in a year. The release and stability of colloids were followed by measuring particle size, colloidal silica concentrations and zeta potential. The particle size distributions were determined applying the dynamic light scattering (DLS) method and zeta potential based on dynamic electrophoretic mobility.In dilute NaCl (10-7–10-2 M) and CaCl2 (3 10-7– 3 10-3 M) solutions, a mean colloid diameter was less than 100 nm and high negative zeta potential values suggests the existence of stable silica colloids. After two years, the mean particle diameter was increased but it was still less than 500 nm and absolute value of zeta potential was decreased. In 0.1–1 M NaCl and 0.03–3 M CaCl2 solutions, wide particle size distribution and zeta potential values around zero suggested particle aggregation and instable colloids. In deionized water, particle size remained rather stable and zeta potential remained high negative suggests stable silica colloids. The threshold value of ionic strength was 0.03–0.1 M when salinity had an effect on the stability of colloids. In Olkiluoto, the ionic strength of saline groundwater is order of magnitude higher than the range of effect value obtained in this study. Under the prevailing conditions in Olkiluoto, silica colloids are instable, but the possible influence of glacial melt waters has to be considered.

Release of Colloids from Injection Grout Silica Sol

2008 ◽  
Vol 1124 ◽  
Author(s):  
Pirkko L Hölttä ◽  
Martti Hakanen ◽  
Mari Lahtinen ◽  
Anumaija Leskinen ◽  
Jukka Lehto ◽  
...  
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Size Distribution ◽  
Colloidal Particle ◽  
Sol Gel ◽  
Silica Sol ◽  
Saline Groundwater ◽  
Low Salinity ◽  
Hydraulic Aperture ◽  
Silica Colloids

AbstractNon-cementitious grouts have been tested in Olkiluoto for the sealing of fractures with the small hydraulic aperture. A promising non-cementitious inorganic grout material for sealing the fractures of the apertures less than 0.05 mm is commercial colloidal silica called silica sol. The use of colloidal material has to be considered in the long-term safety assessment of a spent nuclear fuel repository. Objective of this work was to determine colloid release from the silica sol gel and stability of silica colloids in different groundwater conditions. To use silica sol as a grout, the injected colloids have to aggregate and form a gel within a predictable time by using a saline solution as an accelerator. Silica sol gel samples were stored in contact with medium salinity and low salinity groundwater simulates. Release of silica colloids and colloid stability was followed by analyzing the colloid concentration, particle size distribution, concentration of reactive silicon, solution pH and zeta potential after one month, half a year and one year. Malvern Zetasizer Nano ZS equipment was used to determine colloidal particle size distributions applying the dynamic light scattering method and zeta potential based on dynamic electrophoretic mobility. The colloidal particle concentration was estimated from Zetasizer measurements applying a standard series. Dissolved reactive silica concentration was determined using the molybdate blue method and total silica concentrations were determined using ICP–MS. The release and stability of silica colloids were found to be dependent significantly on groundwater salinity. Zeta potential values near zero and the increase in particle size at first and then the disappearance of large particles indicated particle flocculation or coagulation and instable colloidal dispersion in a saline groundwater simulate. In low salinity ground water simulate high negative zeta potential values, small particle size and constant size distribution indicate the existence of stable silica colloids. The concentrations of the released colloids were slightly higher than determined in natural granitic ground waters. Under prevailing saline groundwater conditions in Olkiluoto no significant release of colloids from silica sol is expected but the possible influence of low salinity glacial melt waters has to be considered.

scholarly journals Synergistic Effect of Laccase and Sugar Beet Pectin on the Properties of Concentrated Protein Emulsions and Its Application in Concentrated Coconut Milk

Molecules ◽  
2018 ◽  
Vol 23 (10) ◽  
pp. 2591 ◽  
Author(s):  
Pusen Chen ◽  
Wenxue Chen ◽  
Shan Jiang ◽  
Qiuping Zhong ◽  
Haiming Chen ◽  
...  
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Particle Size Distribution ◽  
Sugar Beet ◽  
Interfacial Tension ◽  
Size Distribution ◽  
Water Interface ◽  
Oil Water ◽  
Coconut Protein ◽  
The Stability

Concentrated coconut milk (CCM), a raw material from coconut products, is extremely unstable because of its high oil content (>30%). In this study, three model emulsions—primary emulsions stabilized by coconut proteins only, secondary emulsions stabilized by the conjugation of sugar beet pectin (SBP) and coconut protein, and laccase-treated secondary emulsions—were prepared to investigate the effects of different factors (coconut proteins, coconut proteins + SBP, laccase-treated emulsions) on the stability of model emulsions and the application of this method to real CCM. The stability of the emulsions was evaluated based on their interfacial tension, zeta potential, particle size distribution, rheological properties, and the assembly formation of SBP and coconut protein at the oil–water interface. Results showed that addition of SBP or laccase can increase the viscosity and reduce the interfacial tension of the emulsion, and the effect was concentration dependent. Zeta potential of the emulsion decreased with the increase of protein (from −16 to −32 mV) and addition of SBP (from −32 to −46 mV), and it was reduced when laccase was added (from −9.5 to −6.0 mV). The secondary emulsion exhibited the narrowest particle size distribution (from 0.1 to 20 μm); however, laccase-catalyzed secondary emulsions showed the best storage stability and no layering when the laccase content reached 10 U/100 g. Confocal laser scanning microscopy (CLSM) revealed that protein was adsorbed on the oil–water interface and SBP distributed in the continuous phase could undergo oxidative crosslinking by laccase. These results show that the stability of the concentrated emulsion can be effectively improved by adding SBP and laccase.

Effect of Dispersant on the Measurement of Particle Size Distribution of Titanium Dioxide

2012 ◽  
Vol 512-515 ◽  
pp. 261-264
Author(s):  
Li Shen ◽  
Jin Hu ◽  
Da Ping Wu
Keyword(s):  
Particle Size ◽  
Titanium Dioxide ◽  
Zeta Potential ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Anionic Surfactant ◽  
Sodium Sulfate ◽  
Aqueous Media ◽  
Rutile Tio2 ◽  
Tio2 Particles

As anionic surfactant, a commercial salt of lauryl sodium sulfate was used. The effects of different amounts of dispersant on the measurement of particle size distribution between two titanium dioxide powders (anatase and rutile) in aqueous media were discussed. Diluted aqueous suspensions were characterized in terms of particle size distribution and zeta potential. The results demonstrate that the measurement of particle size distribution strongly depends on the amounts of dispersant. The amounts of dispersant have a significant effect on the behavior of the rutile-TiO2 particles. The particle size first decreases significantly with an increase in the amounts of dispersant and then lesser increases with a further increase in the amounts of dispersant. The tendency show significant differences between two particles.

Removal of clay and blue-green algae particles through zeta potential and particle size distribution in the dissolved air flotation process

2006 ◽  
Vol 6 (1) ◽  
pp. 95-103 ◽  
Author(s):  
D.H. Kwak ◽  
S.J. Kim ◽  
H.J. Jung ◽  
C.H. Won ◽  
S.B. Kwon ◽  
...  
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Green Algae ◽  
Dissolved Air Flotation ◽  
Flotation Process ◽  
Clay Particles ◽  
Blue Green Algae ◽  
Dissolved Air

The raw water characteristics of a water treatment plant in Korea are mainly dependent on two major factors: the clay particles attributed to rainfall and blue-green algae in reservoirs. In this work, zeta potential and particle size distributions of clay and algae particles, which are the important parameters affecting their removal efficiency, were measured to investigate the behavior and removal characteristics of particles under various conditions. The results showed that the zeta potential of blue-green algae was more sensitive to treatment conditions than clay, and it fluctuated highly with coagulant dosage, suggesting that the control of zeta potential is important for effective removal of algae particles. On the other hand, the range of particle size distribution that remained from the preliminary sedimentation tank was generally smaller than for flotation. However, the zeta potential of the remaining particles was either close to the isoelectric point or positive, and the particles were not so hard to remove for that reason. In the final analysis, for simultaneous removal of clay and algae particles, a sufficient zeta potential difference must be formed not only for algae particles but also for small clay particles from the sedimentation tank in the dissolved air flotation process.

Effects of Acidity on the Stabilities of Cloudy Apple Juice

2018 ◽  
Vol 789 ◽  
pp. 26-30
Author(s):  
Dan Shi Zhu ◽  
Li Wei Wei ◽  
Xiao Jun Ren ◽  
Xue Hui Cao ◽  
He Liu ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Shelf Life ◽  
Size Distribution ◽  
Apple Juice ◽  
Influence Factor ◽  
Control Group ◽  
Particle Sizes ◽  
Stability Indexes ◽  
The Stability

Acidity is an important influence factor for juice stability. In this study, the effects of acidityon stability of cloudy apple juice were investigated. The stability indexes, such as, turbidity, cloudvalue, cloud stability, and particle size distribution (PSD) were measured at pH 2.0, 2.5, 3.0 and 3.5,along with the untreated juice (pH 3.8) as control group. The results showed that, pH has significanteffects on turbidity, chrome (C*), cloud value, and D50, D90 in PSD of cloudy apple juice. The juicehad a better stabilization at pH 2.5. At this pH condition, the turbidity, cloud value, cloud stability ofjuice was the best. In addition, at pH 2.5, the color of the juice was better, the particles were smaller,and the particle sizes were more uniform. By this study, a theoretical reference could be provided forimproving stability of cloudy apple juice and extending juice shelf life.

scholarly journals Determination of Critical Parameters of Drug Substance Influencing Dissolution: A Case Study

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Erika Bojnanska ◽  
Michal Kalina ◽  
Ladislav Parizek ◽  
Eva Bartonickova ◽  
Tomas Opravil ◽  
...  
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Particle Size Distribution ◽  
Dissolution Rate ◽  
Size Distribution ◽  
Drug Product ◽  
Drug Formulation ◽  
Drug Substance ◽  
Critical Parameters ◽  
Dissolution Profile

The purpose of this study was to specify critical parameters (physicochemical characteristics) of drug substance that can affect dissolution profile/dissolution rate of the final drug product manufactured by validated procedure from various batches of the same drug substance received from different suppliers. The target was to design a sufficiently robust drug substance specification allowing to obtain a satisfactory drug product. For this reason, five batches of the drug substance and five samples of the final peroral drug products were analysed with the use of solid state analysis methods on the bulk level. Besides polymorphism, particle size distribution, surface area, zeta potential, and water content were identified as important parameters, and the zeta potential and the particle size distribution of the drug substance seem to be critical quality attributes affecting the dissolution rate of the drug substance released from the final peroral drug formulation.

scholarly journals Characterization of kaolin dispersion using acoustic and electroacoustic spectroscopy

2008 ◽  
Vol 44 (1) ◽  
pp. 63-72 ◽  
Author(s):  
Z. Dohnalová ◽  
L. Svoboda ◽  
P. Sulcová
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Divalent Cations ◽  
Dispersing Agent ◽  
Time Period ◽  
Ultrasonic Techniques

The objective of this work is the investigation of the kaolin dispersion by the ultrasonic techniques. In contact with aqueous solution clay minerals show cation - exchange properties and certain degree of dissolution or rather selective leaching of components. The work is divided into two main parts - determination of zeta potential and particle size distribution. The first part is focused on measuring of zeta potential. Effects of concentration of solid, different kind of electrolytes (0.01 M KCl, 0.01 M MgCl2 and 0.01 M CaCl2), pH and temperature of the dispersions are investigated. The isoelectric points (IEP) of kaolin suspension are about pH 4-5. Electrolytes containing monovalent cations such as K+ become zeta potential more negative compared to the values obtained with water. Such behavior is explained by the exchange of K+ ions with H+ ions in the system. When the electrolyte is formed by divalent cations such as Mg2+ or Ca2+, the values of zeta potential become less negative than zeta potential of kaolin in water. The second part is focused on the determination of particle size distribution with respect to dispersing conditions, such as the optimal dispersing agent (Na2SiO3, (NaPO3)6, Na4P2O7 or Busperse), time and power of ultrasonication and also the tracking of dispersion stability that is expressed by the measuring of particle size distribution during certain time period.

Chemical Mechanical Polishing Slurry for Tungsten in ULSI With Large Particle Size Colloidal Silica Nano-Abrasive

2005 ◽  
Author(s):  
Kailiang Zhang ◽  
Zhitang Song ◽  
Songlin Feng
Keyword(s):  
Surface Roughness ◽  
Particle Size ◽  
Zeta Potential ◽  
Chemical Mechanical Polishing ◽  
Large Particle ◽  
Colloidal Silica ◽  
Removal Rate ◽  
Silica Sol ◽  
Mechanical Polishing ◽  
Large Particle Size

Silica sol nano-abrasives with large particle are prepared and characterized by TEM, PCS and Zeta potential in this paper. Results show that the silica sol nano-abrasives about 100nm are of higher stability (Zeta potential: −65mV) and narrow distribution of particle size. And then alkali CMP slurries for tungsten containing self-made silica sol nano-abrasives are prepared and applied. CMP results show that the removal rate has been improved to 367nm/min and the RMS of surface roughness has been reduced from 4.4nm to 0.80nm. In sum, one kind of alkali slurry containing 100nm silica sol for tungsten CMP is studied.

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