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.

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.

Simulated rainwater effects on anion exchange capacity and nitrate retention in Ferrosols

Soil Research ◽  
2005 ◽  
Vol 43 (1) ◽  
pp. 33 ◽  
Author(s):  
M. J. Donn ◽  
N. W. Menzies
Keyword(s):  
Ionic Strength ◽  
Surface Charge ◽  
Anion Exchange ◽  
Soil Solution ◽  
Large Scale ◽  
Soil Column ◽  
Experimental Period ◽  
Exchange Capacity ◽  
Soil Columns ◽  
Low Ionic Strength

Nitrate (NO3) accumulations (up to 1880 kg NO3-N/ha for a 12-m profile) in the soils of the Johnstone River catchment (JRC) may pose a serious environmental threat to the Great Barrier Reef lagoon if the NO3 were released. The leaching of artificial rainwater through repacked soil columns was investigated to determine the effect of low NO3/low ionic strength inputs on the NO3 chemistry of the JRC profiles. Repacked soil columns were used to simulate the 11.5-m profiles, and the soil solution anion and cation concentrations were monitored at 10 points throughout the soil column. As the rainwater was applied, NO3 leached down the profile, with substantial quantities exiting the columns. Anion exchange was discounted as the major mechanism of NO3 release due to the substantial net loss of anions from the system (up to 2740 kg NO3-N/ha over the experimental period). As the soils were dominated by variable charge minerals, the effect of changing pH and ionic strength on the surface charge density was investigated in relation to the release of NO3 from the exchange. It was concluded that the equilibration of the soil solution with the low ionic strength rainwater solution resulted in a lessening of both the positive and negative surface charge. Nitrate was released into the soil solution and subsequently leached due to the lessening of the positive surface charge. Loss of NO3 from the soil profile was slow, with equivalent field release times estimated to be tens of years. Although annual release rates were high in absolute terms (up to 175 kg NO3-N/ha.year), they are only slightly greater than the current loss rates from fertilised sugarcane production (up to 50 kg NO3-N/ha.year). In addition to this, the large-scale release of NO3 from the accumulations will only occur until a new equilibrium is established with the input rainwater solution.

scholarly journals Interaction of serum albumin with vinyl sulfonate azo dye

2008 ◽  
Vol 6 (4) ◽  
pp. 509-512 ◽  
Author(s):  
Jolanta Sereikaite ◽  
Vladas-Algirdas Bumelis
Keyword(s):  
Ionic Strength ◽  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Azo Dye ◽  
Dissociation Constants ◽  
Reactive Dye ◽  
Difference Spectroscopy ◽  
Affinity Ligand ◽  
The Stability ◽  
Influence Of Ph

AbstractThe interaction between bovine serum albumin and the mono azo reactive dye Orange ZT has been investigated using absorption difference spectroscopy. The influence of pH and ionic strength of the solution on the stability of the dye-protein complex has been determined. At 25°C, the complex dissociation constants were equal to 24.0, 28.0, 7.0, 11.0, 17.6 and 46.0 μM at pH 7.0, 6.5, 6.0, 5.5, 5.0 and 4.3, respectively. In the presence of 0.1, 0.2, 0.3 M KCl, at pH 6.0 and 25°C, the complex dissociation constants were 8.8, 20.0, 18.0 μM, respectively. The protein-dye complex dissociation constants show that Orange ZT could be used as an affinity ligand for protein purification.

An Experimental Investigation on Thermal Conductivity and Viscosity of Graphene doped CNTs /TiO2 Nanofluid

2020 ◽  
Vol 17 (3) ◽  
Author(s):  
A.M. Zetty Akhtar ◽  
M.M. Rahman ◽  
K. Kadirgama ◽  
M.A. Maleque
Keyword(s):  
Thermal Conductivity ◽  
Zeta Potential ◽  
Base Fluid ◽  
Minimum Quantity Lubrication ◽  
Cutting Fluid ◽  
Cutting Zone ◽  
Observation Method ◽  
The Stability ◽  
The Relationship ◽  
Zeta Potential Analysis

This paper presents the findings of the stability, thermal conductivity and viscosity of CNTs (doped with 10 wt% graphene)- TiO2 hybrid nanofluids under various concentrations. While the usage of cutting fluid in machining operation is necessary for removing the heat generated at the cutting zone, the excessive use of it could lead to environmental and health issue to the operators. Therefore, the minimum quantity lubrication (MQL) to replace the conventional flooding was introduced. The MQL method minimises the usage of cutting fluid as a step to achieve a cleaner environment and sustainable machining. However, the low thermal conductivity of the base fluid in the MQL system caused the insufficient removal of heat generated in the cutting zone. Addition of nanoparticles to the base fluid was then introduced to enhance the performance of cutting fluids. The ethylene glycol used as the base fluid, titanium dioxide (TiO2) and carbon nanotubes (CNTs) nanoparticle mixed to produce nanofluids with concentrations of 0.02 to 0.1 wt.% with an interval of 0.02 wt%. The mixing ratio of TiO2: CNTs was 90:10 and ratio of SDBS (surfactant): CNTs was 10:1. The stability of nanofluid checked using observation method and zeta potential analysis. The thermal conductivity and viscosity of suspension were measured at a temperature range between 30˚C to 70˚C (with increment of 10˚C) to determine the relationship between concentration and temperature on nanofluid’s thermal physical properties. Based on the results obtained, zeta potential value for nanofluid range from -50 to -70 mV indicates a good stability of the suspension. Thermal conductivity of nanofluid increases as an increase of temperature and enhancement ratio is within the range of 1.51 to 4.53 compared to the base fluid. Meanwhile, the viscosity of nanofluid shows decrements with an increase of the temperature remarks significant advantage in pumping power. The developed nanofluid in this study found to be stable with enhanced thermal conductivity and decrease in viscosity, which at once make it possible to be use as nanolubricant in machining operation.

scholarly journals Development and Characterization of Two Types of Surface Displayed Levansucrases for Levan Biosynthesis

Catalysts ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 757
Author(s):  
Huiyi Shang ◽  
Danni Yang ◽  
Dairong Qiao ◽  
Hui Xu ◽  
Yi Cao
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Molecular Weight ◽  
Large Scale ◽  
Surface Display ◽  
Yeast Surface Display ◽  
Fusion Partner ◽  
Whole Cell ◽  
Food Industries ◽  
Yeast Surface ◽  
The Stability

Levan has wide applications in chemical, cosmetic, pharmaceutical and food industries. The free levansucrase is usually used in the biosynthesis of levan, but the poor reusability and low stability of free levansucrase have limited its large-scale use. To address this problem, the surface-displayed levansucrase in Saccharomyces cerevisiae were generated and evaluated in this study. The levansucrase from Zymomonas mobilis was displayed on the cell surface of Saccharomyces cerevisiae EBY100 using a various yeast surface display platform. The N-terminal fusion partner is based on a-agglutinin, and the C-terminal one is Flo1p. The yield of levan produced by these two whole-cell biocatalysts reaches 26 g/L and 34 g/L in 24 h, respectively. Meanwhile, the stability of the surface-displayed levansucrases is significantly enhanced. After six reuses, these two biocatalysts retained over 50% and 60% of their initial activities, respectively. Furthermore, the molecular weight and polydispersity test of the products suggested that the whole-cell biocatalyst of levansucrase displayed by Flo1p has more potentials in the production of levan with low molecular weight which is critical in certain applications. In conclusion, our method not only enable the possibility to reuse the enzyme, but also improves the stability of the enzyme.

Influence of pH and ionic strength on the thermal gelation behaviour of pea protein

2021 ◽  
pp. 106903
Author(s):  
Caren Tanger ◽  
Michaela Müller ◽  
David Andlinger ◽  
Ulrich Kulozik
Keyword(s):  
Ionic Strength ◽  
Pea Protein ◽  
Thermal Gelation ◽  
Influence Of Ph

scholarly journals INTRACISTRONIC MAPPING OF ELECTROPHORETIC SITES IN DROSOPHILA MELANOGASTER: FIDELITY OF INFORMATION TRANSFER BY GENE CONVERSION

Genetics ◽  
1974 ◽  
Vol 76 (2) ◽  
pp. 289-299
Author(s):  
Margaret McCarron ◽  
William Gelbart ◽  
Arthur Chovnick
Keyword(s):  
Drosophila Melanogaster ◽  
Information Transfer ◽  
Large Scale ◽  
Genetic Basis ◽  
Xanthine Dehydrogenase ◽  
Specific Protein ◽  
Wild Type ◽  
Electrophoretic Variation ◽  
The Stability ◽  
Recombination Experiments

ABSTRACT A convenient method is described for the intracistronic mapping of genetic sites responsible for electrophoretic variation of a specific protein in Drosophila melanogaster. A number of wild-type isoalleles of the rosy locus have been isolated which are associated with the production of electrophoretically distinguishable xanthine dehydrogenases. Large-scale recombination experiments were carried out involving null enzyme mutants induced on electrophoretically distinct wild-type isoalleles, the genetic basis for which is followed as a nonselective marker in the cross. Additionally, a large-scale recombination experiment was carried out involving null enzyme rosy mutants induced on the same wild-type isoallele. Examination of the electrophoretic character of crossover and convertant products recovered from the latter experiment revealed that all exhibited the same parental electrophoretic character. In addition to documenting the stability of the xanthine dehydrogenase electrophoretic character, this observation argues against a special mutagenesis hypothesis to explain conversions resulting from allele recombination studies.

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