scholarly journals Comparative Analysis on Dielectric Gold and Aluminium Triangular Junctions: Impact of Ionic Strength and Background Electrolyte by pH Variations

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Iswary Letchumanan ◽  
M. K. Md Arshad ◽  
Subash C. B. Gopinath ◽  
R. D. A. A. Rajapaksha ◽  
S. R. Balakrishnan
Keyword(s):  
Comparative Analysis ◽  
Ionic Strength ◽  
Background Electrolyte ◽  
Ph Variations

scholarly journals Compositional and Temperature Effects on the Rheological Properties of Polyelectrolyte–Surfactant Hydrogels

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 927 ◽  
Author(s):  
Jiří Smilek ◽  
Sabína Jarábková ◽  
Tomáš Velcer ◽  
Miloslav Pekař
Keyword(s):  
Ionic Strength ◽  
Rheological Properties ◽  
Surfactant Concentration ◽  
Background Electrolyte ◽  
Effect Of Temperature ◽  
Physical Interactions ◽  
Chain Conformations ◽  
Oppositely Charged ◽  
Electrolyte Ph ◽  
Positively Charged

The rheological properties of hydrogels prepared by physical interactions between oppositely charged polyelectrolyte and surfactant in micellar form were studied. Specifically, hyaluronan was employed as a negatively charged polyelectrolyte and Septonex (carbethopendecinium bromide) as a cationic surfactant. Amino-modified dextran was used as a positively charged polyelectrolyte interacting with sodium dodecylsulphate as an anionic surfactant. The effects of the preparation method, surfactant concentration, ionic strength (the concentration of NaCl background electrolyte), pH (buffers), multivalent cations, and elevated temperature on the properties were investigated. The formation of gels required an optimum ionic strength (set by the NaCl solution), ranging from 0.15–0.3 M regardless of the type of hydrogel system and surfactant concentration. The other compositional effects and the effect of temperature were dependent on the polyelectrolyte type or its molecular weight. General differences between the behaviour of hyaluronan-based and cationized dextran-based materials were attributed to differences in the chain conformations of the two biopolymers and in the accessibility of their charged groups.

scholarly journals The efficiency of nano-TiO2 and γ-Al2O3 in copper removal from aqueous solution by characterization and adsorption study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Fatemeh Ezati ◽  
Ebrahim Sepehr ◽  
Fatemeh Ahmadi
Keyword(s):  
Aqueous Solution ◽  
Ionic Strength ◽  
Ph Value ◽  
Physical Adsorption ◽  
Geochemical Modeling ◽  
Low Cost ◽  
Background Electrolyte ◽  
Isotherm Models ◽  
Batch Adsorption ◽  
Equilibrium Data

AbstractWater pollution is a major global challenge given the increasing growth in the industry and the human population. The present study aims to investigate the efficiency of TiO2 and γ-Al2O3 nanoadsorbents for removal of copper (Cu(II)) from aqueous solution as influenced by different chemical factors including pH, initial concentration, background electrolyte and, ionic strength. The batch adsorption experiment was performed according to standard experimental methods. Various isotherm models (Freundlich, Langmuir, Temkin, and Dubinin–Radushkevich) were fitted to the equilibrium data. According to geochemical modeling data, adsorption was a predominant mechanism for Cu(II) removal from aqueous solution. Calculated isotherm equations parameters were evidence of the physical adsorption mechanism of Cu(II) onto the surface of the nanoparticles. The Freundlich adsorption isotherm model could well fit the experimental equilibrium data at different pH values. The maximum monolayer adsorption capacity of TiO2 and γ-Al2O3 nanosorbents were found to 9288 and 3607 mg kg−1 at the highest pH value (pH 8) and the highest initial Cu(II) concentration (80 mg L−1) respectively. Copper )Cu(II) (removal efficiency with TiO2 and γ-Al2O3 nanoparticles increased by increasing pH. Copper )Cu(II) (adsorption deceased by increasing ionic strength. The maximum Cu(II) adsorption (4510 mg kg−1) with TiO2 nanoparticles was found at 0.01 M ionic strength in the presence of NaCl. Thermodynamic calculations show the adsorption of Cu(II) ions onto the nanoparticles was spontaneous in nature. Titanium oxide (TiO2) nanosorbents could, therefore, serve as an efficient and low-cost nanomaterial for the remediation of Cu(II) ions polluted aqueous solutions.

scholarly journals Effect of Ionic Strength and Coexisting Ions on the Biosorption of Divalent Nickel by the Acorn Shell of the Oak Quercus crassipes Humb. & Bonpl.

Processes ◽  
2020 ◽  
Vol 8 (10) ◽  
pp. 1229
Author(s):  
Erick Aranda-García ◽  
Griselda Ma. Chávez-Camarillo ◽  
Eliseo Cristiani-Urbina
Keyword(s):  
Ionic Strength ◽  
Aqueous Solutions ◽  
Divalent Cations ◽  
Low Cost ◽  
Background Electrolyte ◽  
Fractional Power ◽  
Negative Effects ◽  
Pseudo Second Order ◽  
Coexisting Ions ◽  
Background Electrolytes

This study investigated the effect of ionic strength and background electrolytes on the biosorption of Ni2+ from aqueous solutions by the acorn shell of Quercus crassipes Humb. & Bonpl. (QCS). A NaCl ionic strength of 0.2 mM was established to have no effect on the Ni2+ biosorption and the biosorption capacity of the heavy metal decreased as the ionic strength increased from 2 to 2000 mM. The background electrolytes (KCl, NaNO3, Na2SO4, CaCl2, MgSO4, and MgCl2) had no adverse effects on the biosorption of Ni2+ at a concentration of 0.2 mM. However, at background electrolyte concentrations of 2 and 20 mM, divalent cations (Ca2+ and Mg2+) had greater negative effects on the biosorption of Ni2+ compared to the monovalent cations (Na+ and K+). Additionally, the SO42− and Cl− anions affected the biosorption of Ni2+. The fractional power, Elovich, and pseudo-second order models represented the kinetic processes of the biosorption of Ni2+ adequately. The results show that QCS can be a promising and low-cost biosorbent for removing Ni2+ ions from aqueous solutions containing various types of impurities with different concentrations.

scholarly journals THERMOCHEMICAL STUDY OF ACID-BASE REACTIONS IN AQUEOUS SOLUTION OF PYRIDOXINE

2020 ◽  
Vol 63 (6) ◽  
pp. 25-29
Author(s):  
Alexander I. Lytkin ◽  
Olga N. Krutova ◽  
Pavel D. Krutov ◽  
Victoriya V. Dudar ◽  
Elena Yu. Tyunina
Keyword(s):  
Ionic Strength ◽  
Confidence Interval ◽  
Thermal Effects ◽  
Vitamin B6 ◽  
Pyridoxal Phosphate ◽  
Background Electrolyte ◽  
The Body ◽  
Water Dissociation ◽  
Thermochemical Study ◽  
Acid Base

Vitamin B6 is one of the most important vitamins necessary for the life of living organisms. Vitamin B6, which in the body is represented by coenzyme forms - pyridoxal phosphate and pyridoxamine phosphate, is a part of more than 100 enzymes. As the object of study, we chose pyridoxine. The thermal effects of interaction of the solution of pyridoxine with solutions of nitric acid and potassium hydroxide at 298.15K and ionic strength values of 0.25; 0.5 and 0.75 against the background of electrolyte-supporting potassium nitrate were measured with direct calorimetric method. The measurements were carried out in a calorimeter with an isothermal shell equipped with a 60 cm3 reaction vessel and electric calibration at T = 298.15 ± 0.01 К and P = 100.5 ± 0.7 kPa and automatic recording of the temperature-time curve. Relative measurement error for heats of dissolution of a standard substance was -0.1-0.3%. Calculation of the equilibrium composition of the system taking into account processes a step dissociation and water dissociation was carried out according to the KEV program. The thermal effects of dissociation of pyridoxine in a standard solution were found by extrapolating the heats of stepwise dissociation at fixed values of ionic strength to zero ionic strength. Since the thermal effects of dilution were measured in three concentration ranges of KNO3, the number of experiments in each series was at least three. To calculate the confidence interval of the average value of DН the Student's criterion was taken at a confidence interval of 0.95. Standard thermodynamic characteristics (DrH°, DrG°, DrS°) of reactions of acid-base interaction in aqueous solutions of pyridoxine were calculated. With an increase in the background electrolyte concentration, the endothermicity of stepwise pyridoxine ionization processes increases.

scholarly journals Software development for calculating concentration in a buffer to the preparation of background electrolyte in the analytical method of capillary electrophoresis

2021 ◽  
Vol 63 (11) ◽  
pp. 29-34
Author(s):  
Thanh Dam Nguyen ◽  
◽  
Thi Phuc Nguyen ◽  
Minh Tuan Vu ◽  
◽  
...  
Keyword(s):  
Capillary Electrophoresis ◽  
Ionic Strength ◽  
Software Development ◽  
Analytical Method ◽  
Approximate Calculation ◽  
Background Electrolyte ◽  
C Language ◽  
Ph Adjustment ◽  
Ph Values ◽  
Acids And Bases

pH buffers of weak organic acids and bases are essential in capillary electrophoresis (CE) analyses, primarily when contactless conductivity detectors (C4D) are used. However, the preparation of a buffer with a known concentration of one component for use as a background electrolyte (BGE) in CE-C4D usually requires a pH adjustment to the desired value and an approximate calculation to estimate the concentration of the second component. This study developed software that allowed determining the concentration of one component when knowing the concentration of another component and the pH of the solution, taking into account the influence of ionic strength. The software was built in C# language with Windows Form interface on Microsoft Visual Studio. With the concentrations calculated from the developed software, the differences (|ΔpH|) between pH values of the obtained BGEs in practice and the desired values were smaller than 0.07, corresponding to the errors of less than 2%.

scholarly journals Comparative analysis of ionic strength tolerance between freshwater and marine Caulobacterales adhesins

2019 ◽  
Author(s):  
Nelson K. Chepkwony ◽  
Cécile Berne ◽  
Yves V. Brun
Keyword(s):  
Comparative Analysis ◽  
Chemical Composition ◽  
Ionic Strength ◽  
Physicochemical Properties ◽  
Bacterial Adhesion ◽  
Marine Bacterium ◽  
Caulobacter Crescentus ◽  
High Ionic Strength ◽  
Shear Forces ◽  
Surface Attachment

ABSTRACTBacterial adhesion is affected by environmental factors, such as ionic strength, pH, temperature, and shear forces, and therefore marine bacteria must have developed holdfasts with different composition and structures than their freshwater counterparts to adapt to their natural environment. The dimorphic α-proteobacterium Hirschia baltica is a marine budding bacterium in the Caulobacterales clade. H. baltica uses a polar adhesin, the holdfast, located at the cell pole opposite the reproductive stalk for surface attachment and cell-cell adhesion. The holdfast adhesin has been best characterized in Caulobacter crescentus, a freshwater member of the Caulobacterales, and little is known about holdfast composition and properties in marine Caulobacterales. Here we use H. baltica as a model to characterize holdfast properties in marine Caulobacterales. We show that freshwater and marine Caulobacterales use similar genes in holdfast biogenesis and that these genes are highly conserved among the two genera. We also determine that H. baltica produces larger holdfast than C. crescentus and that those holdfasts have a different chemical composition, as they contain N-acetylglucosamine and galactose monosaccharide residues and proteins, but lack DNA. Finally, we show that H. baltica holdfasts tolerate higher ionic strength than those of C. crescentus. We conclude that marine Caulobacterales holdfasts have physicochemical properties that maximize binding in high ionic strength environments.IMPORTANCEMost bacteria spend a large amount of their lifespan attached to surfaces, forming complex multicellular communities called biofilms. Bacteria can colonize virtually any surface, therefore they have adapted to bind efficiently in very different environments. In this study, we compare the adhesive holdfasts produced by the freshwater bacterium C. crescentus and a relative, the marine bacterium H. baltica. We show that H. baltica holdfasts have a different morphology and chemical composition, and tolerate high ionic strength. Our results show that H. baltica holdfast is an excellent model to study the effect of ionic strength on adhesion and providing insights on the physicochemical properties required for adhesion in the marine environment.

Magnesium binding by terrestrial humic acids

2018 ◽  
Vol 15 (6) ◽  
pp. 317 ◽  
Author(s):  
Iso Christl
Keyword(s):  
Trace Elements ◽  
Ionic Strength ◽  
Functional Groups ◽  
Humic Acids ◽  
Specific Binding ◽  
Background Electrolyte ◽  
Essential Element ◽  
Cation Binding ◽  
Ion Hydration ◽  
Magnesium Binding

Environmental contextThe behaviour of magnesium, which is an essential element for all living organisms, in terrestrial environments is influenced by natural organic matter. This study shows that magnesium binding by terrestrial humic acids exhibits a pronounced ionic strength-dependence indicating a strong preference for electrostatic binding to humic acids. This interaction is expected to influence the mobility of humic substances and their associated trace elements. AbstractMagnesium binding by three terrestrial humic acids was investigated at pH 8 and 25 °C as a function of Mg2+ activity and ionic strength using NaCl as the background electrolyte. The Mg2+ activity in solution was directly measured with an Mg2+-selective electrode in the titration experiments. In addition, coagulation experiments using Ca2+ and Mg2+ as the coagulants were carried out at pH 8. For the titration data, the NICA–Donnan model was used to quantitatively describe Mg2+ binding to the humic acids considering electrostatic and specific Mg2+ binding. Mg2+ binding to humic acids was found to be strongly affected by ionic strength variations indicating that Mg2+ binding largely arose from electrostatic (nonspecific) interactions with negatively charged functional groups of the humic acids. Data modelling suggested that the relative contribution of specific binding increased with decreasing Mg2+ activity and was related to functional groups with low proton affinities. For all three humic acids studied, the fitted Mg2+ affinity constants for specific binding were lower than the respective Ca2+ affinities. Corresponding to the observed differences in cation binding and the known differences in ion hydration, Ca2+ was observed to be the stronger coagulant as compared with Mg2+. The results suggest that Mg2+ may influence the mobility of trace elements that are strongly bound to humic acids such as mercury, although Mg2+ is not expected to directly compete with strongly sorbing elements for specific binding.

scholarly journals Ionic strength effect on deprotonation of para-sulfonatocalix[4]arene

2013 ◽  
Vol 78 (5) ◽  
pp. 681-688 ◽  
Author(s):  
Mohammad Faraji ◽  
Ali Farajtabar ◽  
Farrokh Gharib
Keyword(s):  
Ionic Strength ◽  
Background Electrolyte ◽  
Sodium Perchlorate ◽  
Multivariate Curve Resolution ◽  
Hydroxyl Group ◽  
Ionic Strength Effect ◽  
Star Program ◽  
Show Evidence ◽  
Ph Range ◽  
Absorbance Data

The deprotonation of para-sulfonatocalix[4]arene were studied by a combination of spectrophotometric and potentiometric methods at 25?C. The ionic strength of solutions was kept constant by sodium perchlorate as background electrolyte at 0.10 to 4.0 mol dm-3. Potentiometer was calibrated according to Gran method for each ionic strength. Spectral changes show evidence for proton dissociation of only one hydroxyl group of calixarene in the studied pH range of 2-10. The pKa values were calculated using STAR program by multivariate curve resolution of absorbance data. Results indicate that the acid-base behavior of para-sulfonatocalix[4]arene varies strongly with increasing ionic strength of solution. The dependence of deprotonation constants on ionic strength were explained by means of Specific ion Interaction Theory (SIT). Activity coefficients of species were modeled by a modified SIT approach. The specific ion interaction parameters were extracted associated with thermodynamic deprotonation constant of para-sulfonatocalix[4]arene.

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