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.

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.

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.

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 SYNTHESIS AND STABILITY OF RESVERATROL-CONJUGATED GOLD NANOPARTICLES MODIFIED WITH POLYETHYLENE GLYCOL

2020 ◽  
pp. 230-236
Author(s):  
RADITYA ISWANDANA ◽  
RICHA NURSELVIANA ◽  
SUTRIYO SUTRIYO
Keyword(s):  
Particle Size ◽  
Gold Nanoparticles ◽  
Polyethylene Glycol ◽  
Zeta Potential ◽  
High Performance ◽  
Entrapment Efficiency ◽  
Test Results ◽  
Novel Method ◽  
The Stability ◽  
Phosphate Buffered Saline

Objective: Gold nanoparticles (AuNPs) are highly useful for drug delivery, but their application is limited by their stability as they readily aggregate.This issue can be prevented by adding a stabilizing agent such as resveratrol (RSV), which is a polyphenol derived from plants, that is used to preventcancer. Therefore, we propose a novel method to prepare stable RSV-conjugated nanoparticles modified with polyethylene glycol (RSV-AuNP-PEG).Methods: In the first step, the Turkevich method was used to synthesize the AuNPs. Then, PEG was added as stabilizer agent and conjugated with RSV.The synthesized conjugates were characterized using ultraviolet-visible spectrophotometry, Fourier transform infrared spectroscopy, particle sizeanalysis, and high-performance liquid chromatography.Results: The obtained RSV-AuNP-PEG had a particle size of 83.93 nm with a polydispersity index (PDI) of 0.562 and formed a translucent purple-redfluid in solution. The zeta potential was −22.9 mV, and the highest entrapment efficiency was 75.86±0.66%. For comparison, the RSV-AuNP solutionwas purple and turbid, the particle size was 51.97 nm with a PDI of 0.694, and the zeta potential was −24.6 mV. The stability test results showed thatthe storage stability of RSV-AuNP-PEG was better than that of AuNP-RSV. Further, the RSV-AuNP-PEG was shown to be most stable in 2% bovine serumalbumin (BSA) while the AuNP-RSV was most stable in 2% BSA in phosphate-buffered saline pH 7.4.Conclusion: These results show that modification of RSV-conjugated AuNPs with PEG effectively prevents their aggregation in storage, but only incertain mediums.

scholarly journals Effect of Potato Pulp Pectic Polysaccharide on the Stability of Acidified Milk Drinks

Molecules ◽  
2020 ◽  
Vol 25 (23) ◽  
pp. 5632
Author(s):  
Weixuan Sun ◽  
Wenhan Yang ◽  
Yuxue Zheng ◽  
Huiling Zhang ◽  
Haitian Fang ◽  
...  
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Neutral Sugar ◽  
Lower Serum ◽  
Pectic Polysaccharide ◽  
Potato Pulp ◽  
Lower Viscosity ◽  
Stabilizing Effect ◽  
New Ideas ◽  
The Stability

In order to broaden the application of potato pulp pectic polysaccharide (PPP) in stabilizing acidified milk drinks (AMDs) and investigate the stabilizing effect and physical properties of AMDs prepared with PPP, a comparative study was made among PPP, commercial high methoxyl pectin (HMP) and low methoxyl pectin (LMP). The zeta potential, rheology, particle size and serum separation of AMDs were evaluated after preparing with PPP, HMP and LMP, respectively. Results indicated that PPP led to lower serum separation than LMP (14.65% for AMDs prepared with 0.5% PPP compared to 25.05% for AMDs prepared with 0.5% LMP), but still higher than HMP (9.09% for AMDs prepared with 0.5% HMP). However, narrower particle size distribution and lower viscosity of AMDs was achieved by PPP than by LMP and HMP. PPP can electrostatically adsorb on the surface of casein and its abundant neutral sugar side chains would provide steric hindrance to prevent casein flocculation in AMDs. Our results might provide some new ideas for the application of PPP in improving the stability of AMDs.

scholarly journals Zeta potential of bacterial cells: Effect of wash buffers

2017 ◽  
Author(s):  
Wenfa Ng ◽  
Yen-Peng Ting
Keyword(s):  
Ionic Strength ◽  
Zeta Potential ◽  
Cell Surface ◽  
Bacterial Cell ◽  
Phosphate Buffer ◽  
Defined Medium ◽  
Deionized Water ◽  
Nonspecific Adsorption ◽  
E Coli ◽  
Ph Range

Zeta potential, defined as the electric charge at the shear plane, is widely used as a proxy parameter for bacterial cell surface charge. Nonspecific adsorption of ions or polyelectrolytes onto the cell surface, however, alters the value and polarity of the measured zeta potential, leading to erroneous results. Multiple wash and centrifugation steps are commonly used in preparing cells for zeta potential analysis, where various wash buffers (such as 9 g/L NaCl, 0.001M KCl, and 0.1M NaNO3) are routinely used for removing (by charge screening) ions and charged molecules that bind nonspecifically to the cell surface. Using Escherichia coli DH5α grown in LB Lennox (with 2 g/L glucose), experiment data showed that the zeta potential-pH profile was not significantly different over the pH range from 2 to 12 for deionized water, 9 g/L NaCl, and phosphate buffer saline (PBS) wash buffers. As LB Lennox is a low salt medium without a phosphate buffer, it was likely that the extent of nonspecific adsorption of ions on the cell surface was not severe, and the different wash buffers would correspondingly not exert much effect on measured zeta potential. Zeta potential-pH profiles for E. coli grown in a semi-defined medium (with a high capacity phosphate buffer system), on the other hand, was significantly different over the pH range from 1 to 12 for deionized water, 9 g/L NaCl, 0.1M NaNO3, 0.1M sodium acetate, and 0.1M sodium citrate wash buffers with the deviation positively correlated with wash buffer’s ionic strength. Furthermore, the point of zero charge (pHzpc) for E. coli grown in the semi-defined medium varies between 1.5 and 3, in an ionic strength dependent manner, for the various wash buffers tested. Collectively, this preliminary study highlights the importance of wash buffer ionic strength in affecting removal efficiency of non-specifically absorbed ions on bacterial cell surface, where a threshold exists (0.15M) for charge screening to be effective. At the upper bound, 0.6M ionic strength might remove cations intrinsic to the cell envelope, leading to possible cell surface damage and erroneous measurements.

scholarly journals The Effect of the Liposomal Encapsulated Saffron Extract on the Physicochemical Properties of a Functional Ricotta Cheese

Molecules ◽  
2021 ◽  
Vol 27 (1) ◽  
pp. 120
Author(s):  
Zahra Siyar ◽  
Ali Motamedzadegan ◽  
Jafar Mohammadzadeh Milani ◽  
Ali Rashidinejad
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Encapsulation Efficiency ◽  
Textural Properties ◽  
Constant Concentration ◽  
Soy Lecithin ◽  
Significant Difference ◽  
Saffron Extract ◽  
The Stability ◽  
Potential Stability

In this study, the encapsulation of saffron extract (SE) was examined at four various concentrations of soy lecithin (0.5%–4% w/v) and constant concentration of SE (0.25% w/v). Particle size and zeta potential of liposomes were in the range of 155.9–208.1 nm and −34.6–43.4 mV, respectively. Encapsulation efficiency was in the range of 50.73%–67.02%, with the stability of nanoliposomes in all treatments being >90%. Encapsulated SE (2% lecithin) was added to ricotta cheese at different concentrations (0%, 0.125%, 1%, and 2% w/v), and physicochemical and textural properties of the cheese were examined. Lecithin concentration significantly (p ≤ 0.05) affected the particle size, zeta potential, stability, and encapsulation efficiency of the manufactured liposomes. In terms of chemical composition and color of the functional cheese, the highest difference was observed between the control cheese and the cheese enriched with 2% liposomal encapsulated SE. Hardness and chewiness increased significantly (p ≤ 0.05) in the cheeses containing encapsulated SE compared to the control cheese. However, there was no significant difference in the case of adhesiveness, cohesiveness, and gumminess among different cheeses. Overall, based on the findings of this research, liposomal encapsulation was an efficient method for the delivery of SE in ricotta cheese as a novel functional food.

ROSUVASTATIN CALCIUM LOADED CHITOSAN NANOPARTICLES: PREPARATION EVALUATION AND IN VITRO RELEASE STUDIES

2020 ◽  
pp. 95-102
Author(s):  
SUVARNA G. BHOKARE ◽  
RAJENDRA P. MARATHE
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Sustained Release ◽  
Sodium Tripolyphosphate ◽  
Chitosan Nanoparticles ◽  
In Vitro Release ◽  
Particle Diameter ◽  
Vitro Release ◽  
Rosuvastatin Calcium

Objective: The objective of the present study was to develop sustained release biodegradable polymeric nanoparticles of rosuvastatin calcium. Methods: Nanoparticles were prepared by modified ionotropic gelation method using 3² full factorial designs. From the preliminary trials, the constraints for independent variables X1 (concentration. of chitosan) and X2 (concentration. of sodium tripolyphosphate) have been fixed. Factors included concentration of chitosan and sodium tripolyphosphate, have been examined to investigate effect on particle size, encapsulation efficiency, zeta potential, % release, scanning electron microscopy, Fourier transfer infrared study and X-ray diffraction and release study of rosuvastatin calcium nanoparticles. 0 Results: The prepared nanoparticles were white, free-flowing and spherical in shape. The infrared spectra showed stable character of rosuvastatin calcium in the drug-loaded nanoparticles and revealed the absence of drug polymer interactions. The chitosan nanoparticles have a particle diameter ranging approximately 114.5±3.61 to 724±.2.51 nm and a zeta potential-13.12 to-52.63 mV. The in vitro release behavior from all the drug loaded batches were found to follow first order and provided sustained release over a period of 10 h. The Zeta potential of all the batches were in the range of-13.12 to-52.63 mv. The release profiles of all batches were very well fitted by Korsmeyer Peppas model. Conclusion: The best-fit release kinetics was achieved with Korsmeyer peppas model. The release of rosuvastatin calcium was influenced by the drug to polymer ratio and particle size. These results indicate that rosuvastatin calcium nanoparticles could be effective in sustaining drug release for a prolonged period.

Impact of ZnO Concentration on the Stability of Agglomerates of TiO2 Engineered Nanoparticles: Effects of the pH, Ionic Strength and Zeta Potential

2020 ◽  
Vol 1012 ◽  
pp. 167-172
Author(s):  
Elizabeth Mendes de Oliveira ◽  
Izabella Christynne Ribeiro Pinto Valadão ◽  
Jose Adilson de Castro ◽  
Leonardo Martins da Silval ◽  
Darlene Souza da Silva ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Zeta Potential ◽  
Large Scale ◽  
Soil Column ◽  
Equilibrium Concentration ◽  
Engineered Nanoparticles ◽  
Leaching Experiments ◽  
The Stability ◽  
Potential Interactions ◽  
Influence Of Ph

The stability of nanoparticles in natural aquatic systems is of great interest to the environmental risk assessment. The relevance of this study lies in the fact that nanoparticles are being produced and used in commercial products on a large scale, which makes the need to study its transport through the environment, especially in soil and water important due to their potential interactions with the ecosystems. In this research, the effects of nanoparticles of zinc oxide (NPZnO) in the behavior of nanoparticles of titanium dioxide (NPTiO2) was investigated. The influence of pH, ionic strength and zeta potential of the hazardous nanoparticles into soil landfills are studied using experimental procedures. Leaching experiments were prepared within soil column simulating landfills layers. Leaching experiments were carried out to simulate the capture and attenuation of these nanomaterials in municipal waste landfills. The results found that the presence of NPTiO2 in suspensions increases the stability of the suspensions keeping higher nanoparticles concentrations, while NPZnO promotes rapid sedimentation with lower equilibrium concentration of nanoparticles.

Stability of nano-sized titanium dioxide in an aqueous environment: effects of pH, dissolved organic matter and divalent cations

2013 ◽  
Vol 68 (2) ◽  
pp. 276-282 ◽  
Author(s):  
X. N. Yang ◽  
F. Y. Cui
Keyword(s):  
Particle Size ◽  
Titanium Dioxide ◽  
Organic Matter ◽  
Zeta Potential ◽  
Dissolved Organic Matter ◽  
Ph Value ◽  
Divalent Cations ◽  
Aqueous Environment ◽  
Nano Tio2 ◽  
The Stability

Nano-sized titanium dioxide in the aquatic environment has a potential impact on the environment and human health. In this study, the impact of pH value, dissolved organic matter (DOM) and divalent cations (Ca2+) on the stability of titanium dioxide nanoparticles (nano-TiO2) in an aqueous environment was investigated in batch tests. The results showed that the particle size of nano-TiO2 was not sensitive to pH value but was inversely proportional to zeta potential. The nano-TiO2 becomes more stable with surface zeta potential, accompanied by small particle size and high dispersion. In the presence of DOM, the particle size was smaller and the stability of nano-TiO2 could be enhanced. This might be a synergistic effect of the ligand exchange and electrostatic force. Particle size increased with the addition of Ca2+ and the stability decreased.

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