Viscosity Of Aqueous Solutions Research Articles

Computing solubility and thermodynamic properties of H2O2 in water

Hydrogen peroxide plays a key role in many environmental and industrial chemical processes. We performed classical Molecular Dynamics and Continuous Fractional Component Monte Carlo simulations to calculate thermodynamic properties of H2O2 in aqueous solutions. The quality of the available force fields for H2O2 developed by Orabi and English (2018) [67], and by Cordeiro (2014) [69] was systematically evaluated. To assess which water force field is suitable for predicting properties of H2O2 in aqueous solutions, four widely used water force fields were used, namely the TIP3P, TIP4P/2005, TIP5P-E, and a modified TIP3P force field. While the computed densities of pure H2O2 in the temperature range of 253 - 353 K using the force field by Orabi & English are in excellent agreement with experimental results, the densities using the force field by Cordeiro are underestimated by 3%. The TIP4P/2005 force field in combination with the H2O2 force field developed by Orabi & English can predict the densities of H2O2 aqueous solution for the whole range of H2O2 mole fractions in very good agreement with experimental results. The TIP4P/2005 force field in combination with either of the H2O2 force fields can predict the viscosities of H2O2 aqueous solutions for the whole range of H2O2 mole fractions in reasonably good agreement with experimental results. The computed diffusion coefficients for H2O2 and water molecules using the TIP4P/2005 force field with either of the H2O2 force fields are almost constant for the whole range of H2O2 mole fractions. Hydrogen bond analysis showed a steady increase in the number of hydrogen bonds with the solute concentrations in H2O2 aqueous solutions for all combinations except for the Cordeiro-TIP5P-E and Orabi-TIP5P-E systems, which showed a minimum at intermediate concentrations. The Cordeiro force field for H2O2 in combination with either of the water force fields can predict the Henry coefficients of H2O2 in water in better agreement with experimental values than the force field by Orabi & English.

Dynamics of Formamide-Water Mixtures Investigated by Linear and Nonlinear Infrared Spectroscopy.

Formamide (FA) exhibits complete miscibility with water, offering a simplified model for exploring the solvation dynamics of peptide linkages in biophysical processes. Its liquid state demonstrates a three-dimensional hydrogen bonding network akin to water, reflecting solvent-like behavior. Analyzing the microscopic structure and dynamics of FA-water mixtures is expected to provide crucial insights into hydrogen bonding dynamics─a key aspect of various biophysical phenomena. This study is focused on the dynamics of FA-water mixtures using linear and femtosecond infrared spectroscopies. By using the intrinsic OD stretch and extrinsic probe SCN-, the local vibrational behaviors across various FA-water compositions were systematically investigated. The vibrational relaxation of OD stretch revealed a negligible impact of FA addition on the vibrational lifetime of water molecules, underscoring the mixture's water-like behavior. However, the reorientational dynamics of OD stretch slowed with increasing FA mole fraction (XFA), plateauing beyond XFA > 0.5. This suggests a correlation between OD's reorientational time and the strength of the hydrogen bond network, likely tied to the solution's changing dielectric constant. Conversely, the vibrational relaxation dynamics of SCN- was strongly correlated with XFA, highlighting a competition between water and FA molecules in solvating SCN-. Moreover, a linear relationship between rising viscosity and the prolonged correlation time of SCN-'s slow dynamics indicates that the solution's macroscopic viscosity is dictated by the extended structures formed between FA and water molecules. The relation between the reorientation dynamics of the SCN- and the macroscopic viscosity in aqueous FA-water mixture solutions was analyzed by using the Stokes-Einstein-Debye equations. The direct viscosity-diffusion coupling is observed, which can be attributed to the homogeneous dynamics feature in FA-water mixture solutions. The inclusion of these intrinsic and extrinsic probes not only enhances the comprehensiveness of our analysis but also provides valuable insights into various aspects of the dynamics within the FA-water system. This investigation sheds light on the fundamental dynamics of FA-water mixtures, emphasizing their molecular-level homogeneity in this binary mixture solution.

Effect of CaCl2 on the micromorphology of a self-thickening agent (TZXJ) for acidizing diversion

The effect of CaCl2 on the micromorphology of a self-thickening agent (TZXJ) was investigated. This study involved analyzing the compositional changes in acid solutions during acid–rock reactions. It combined dynamic light scattering and viscosity testing to confirm that the presence of CaCl2 enhances the aggregation strength of the TZXJ network structure in acid solutions. This enhancement is macroscopically evident as an increase in viscosity. Incorporating 10 % CaCl2 as a promoter into a fresh acid solution, the hydrodynamic radius (Rh) distribution of TZXJ in varying reaction stages was analyzed using dynamic light scattering experiments. The results indicated that the promoter CaCl2 further strengthens the network association of the TZXJ acid solution, thereby improving its thickening capability. Investigating the viscosity of TZXJ aqueous solutions with varying concentrations of CaCl2 revealed that TZXJ exhibits notable salt-thickening effects and can withstand saturated CaCl2 solutions. The microstructural aggregation state and morphology of TZXJ in aqueous solutions were characterized at different CaCl2 concentrations. Dynamic light scattering results demonstrated an increase in the Rh of TZXJ solutions with CaCl2 concentrations. In particular, the mean Rh of a 0.8 % TZXJ solution increased from 150.8 nm to 3078.93 nm. Ultraviolet spectral analysis confirmed that the absorption intensity of the TZXJ solutions increased with CaCl2 concentration, indicating a strengthened network aggregate structure in the TZXJ solutions. Microscopic observations using environmental scanning electron microscopy and transmission electron microscopy revealed that under the influence of calcium chloride, the microstructure of TZXJ transitions from a non-associated, linear carbon chain skeleton to a dense, aggregated network structure. The findings of this study offer theoretical insights for researching polymers resistant to extreme concentrations of CaCl2.

Ultrasonic Velocity and Related Parameters Study of PCE Water-Soluble Polymer

Density, viscosity and ultrasonic velocity of aqueous solutions of polycarboxylate ether [PCE] superplastiziser polymer at one of a thoughtful concentrations and temperatures (298.15, 303.13, 308.15 and 313.15)K. different interplay parameters were calculated by the investigational values of density, viscosity and ultrasonic velocity of polycarboxylate ether Water-Soluble Polymer. The viscosity of superplastiziser polymer solution will increase with growing awareness of aqueous answers of polycarboxylate ether. The ultrasonic speed increases from 298.15 K to 308.15K, at that time yet again decreases for 313.15K because the temperature will increase, density, adiabatic compressibility and intermolecular free length duration lower and ultrasonic velocities, acoustic impedance, molar volumes and molar sound velocities turned into discovered to will increase. The ultrasonic velocities to start with boom then decreases with growing consciousness of polycarboxylate ether. For 0.05 polycarboxylate ether it indicates most ultrasonic velocities

The physicochemical and DNA binding studies of ceftazidime pentahydrate and cefotaxime sodium in aqueous medium

Abstract Ceftazidime pentahydrate (CP) and cefotaxime sodium (CS) are semisynthetic cephalosporin antibiotics and are used to treat a variety of diseases worldwide. In order to explore the efficiency of a medicinal compound, it is important to have a deep understanding of its solution and physiochemical behaviour along with its interaction with biological molecules. In this regard, the solution of two drugs i.e., ceftazidime pentahydrate (CP) and cefotaxime sodium (CS) were investigated in detail. The physicochemical properties of drugs solutions and their interaction with deoxyribonucleic acid (DNA) were studied in water under varying experimental parameters. In the present study the physicochemical properties such as density, viscosity, surface tension, and conductance of aqueous solution, having various molar concentrations, of CP and CS were traced out at different temperatures. Five various concentrations (0.05, 0.1, 0.15, 0.2, and 0.3 mol dm−3) of each drug in an aqueous medium were prepared separately, and the physicochemical properties of each solution, were studied individually at temperatures such as 293, 303, 313, 323, and 333 K respectively. Most of these parameters have shown different behaviour with varying concentration of solution and temperature of the medium. In addition, these drugs showed a spontaneous surface-active and association behaviour in aqueous solutions and drug DNA solution. The flow behaviour, surface properties, volumetric behaviour and solute–solvent interaction of this drug were prominently influenced by experimental variables. UV-Visible spectroscopy was also used to study the interaction of these drugs with DNA in aqueous media in detail. Calculated values of binding constants (K b) for all drug–DNA are positive, indicating constructive binding and interactions between the molecules. In addition the binding efficiency of ceftazidime pentahydrate was found more than that of cefotaxime sodium. The interaction of drug–DNA was not only affected by the nature of the drug but also by the drug-to-DNA ratio and nature of the medium used.

Protein Preferential Solvation in (Sucralose + Water) Mixtures.

Addition of sugars such as sucrose to aqueous protein solutions generally stabilizes proteins against thermal denaturation by preferential exclusion of sugars from proteins (preferential hydration of proteins). In this study, we investigated the effect of sucralose, a chlorinated sucrose derivative, on protein stability and preferential solvation. Circular dichroism and small-angle X-ray scattering measurements showed that sucrose increased the denaturation temperature of myoglobin and was preferentially excluded from the protein, whereas sucralose decreased the denaturation temperature of myoglobin and was preferentially adsorbed to the protein. No clear evidence was obtained for the indirect effects of sucralose on protein destabilization via the structure and properties of solvent water from the physicochemical properties (mass density, sound velocity, viscosity, and osmolality) of aqueous sucralose solutions; therefore, we concluded that a direct protein-sucralose interaction induced protein destabilization.

Anomalous Concentration Dependence of Viscosity: Hidden Role of Cross-Correlations in Aqueous Electrolyte Solutions.

The viscosity of aqueous electrolyte solutions exhibits well-known composition-dependent anomalies that show certain definitive trends and universal features. The viscosity of LiCl and NaCl solutions increases with concentration in a monotonic fashion, while solutions of KCl, RbCl, and CsCl exhibit a more complex behavior. Here, the viscosity first decreases and then increases with increasing concentration, with a rather broad minimum at intermediate concentrations (ca. 1-3 m). To unearth the origin of such puzzling behavior, we carried out detailed molecular-level analyses by interrogating the exact Green-Kubo expression of viscosity in terms of the stress-stress time correlation function (SS-TCF). The total SS-TCF can be decomposed into a collection of three self- and three cross-SS-TCFs arising from the three constituent components (water, cations, and anions). Mode coupling theory (MCT) analysis for the friction on ions and the viscosity of the solution suggests the possible importance of two-particle static and time-dependent cross-correlations between water and the ions. We calculate the viscosity and other dynamical properties for all five electrolyte (LiCl, NaCl, KCl, RbCl, and CsCl) solutions over a range of concentrations, using two models of water (SPC/E and TIP4P/2005). The total viscosity derives non-negligible contributions from all of the terms. The cross-correlations are found to be surprisingly large and seen to play a hidden role in the concentration dependence. However, the importance of cross-correlations is often not discussed. Our study leads to a theoretical understanding of the microscopic origin of the observed anomalies in the composition dependence of viscosity across all five electrolytes.

Structure of aqueous alkali metal halide electrolyte solutions from molecular simulations of phase-transferable polarizable models

The structure of aqueous solutions of alkali metal halides is studied under ambient thermodynamic conditions and concentrations from infinite dilution to supersaturation using molecular dynamics simulations of phase-transferable polarizable models. The results of the solution densities, radial distribution functions, 3D spatial distribution functions, the properties of hydrogen and other noncovalent bonds in solutions, hydration numbers, coordination numbers, numbers of contact cation-anion pairs, and other statistics of the number of ions hydrated simultaneously by a shared water molecule are systematically presented. In particular, the results show and quantify how the strengths of the hydration bonds of different ions vary and how the hydration numbers decrease with increasing concentration in parallel with an increase in the number of contact cation-anion pairs. In most cases, they completely compensate for the loss of water-ion bonds by an increase in cation-anion bonds. An exception are solutions based on the Li+ cation, which retain a solid hydration shell even at high concentrations. This behavior is conceptualized on the basis of three imaginary driving forces: the first dominating at low concentrations and causing full hydration of the ions, the second representing a lack of water necessary for full hydration of the ions and increasing with increasing concentration, and the third attracting counterions to the water-unoccupied sites of the hydration shells and also increasing with concentration. This concept can be used not only to understand the structural behavior of homogeneous electrolytes in thermodynamic equilibrium but also to study phenomena that involve preferential adsorption of ions on electrodes, in nanochannels, or porous materials. The data obtained for the number and strength of hydration bonds and ion pairs can also be used in further studies to elucidate the diffusion behavior, viscosity, and conductivity of aqueous electrolyte solutions.

Machine learning techniques for the estimation of viscosity and density of aqueous solutions in piezo-actuated 3D-printed cells

Machine learning techniques for the estimation of viscosity and density of aqueous solutions in piezo-actuated 3D-printed cells

Dielectric relaxation and thermodynamic study of aqueous Glycine using time domain reflectometry technique

Using the Time Domain Reflectometry technique in the frequency range of 10 MHz to 50 GHz, the complex permittivity spectra of Glycine (Gly) with water combination have been determined over the complete concentration range of mole fractions and in temperature range of 10–25 °C. The Cole-Davidson model was used to fit the intricate permittivity spectra for Gly and water.The non-linear least square fit method has been used to compute the static dielectric constant (ε0), relaxation time (τ), effective Kirkwood correlation factor (geff), excess permittivity (ε0E), (1/τ)E excess inverse relaxation time (1/τ)E and Bruggeman factor (fB). An automated density and sound velocity meter, the Anton Paar DSA 5000 M and viscosity with Lovis 2000 M/ME, was used to measure the density, sound velocity, and viscosity of aqueous solutions. FT-IR spectra are used to identify the conformation assessments of hydrogen bonding development between complicated mixtures.

Rheological properties and color indexes of ultrasonic treated aqueous solutions of basil, Lallemantia, and wild sage gums

This research aimed to analyze the impacts of sonication on the rheological properties and color indexes of aqueous solutions of Basil seed gum (BSG), Lallemantia seed gum (LSG), and Wild sage seed gum (WSG). The apparent viscosity (AV) of aqueous solutions of gums decreased with increasing shear rate (SR) from 12.2 s−1 to 134.5 s−1. Also, the AV (at SR = 61 s−1) of BSG, LSG, and WSG solutions reduced from 0.015 to 0.006 Pa.s, 0.023 to 0.010 Pa.s, and 0.009 to 0.004 Pa.s with enhancing the sonication time from 0 to 20 min, respectively. Various rheological equations were employed to fit the empirical values, and the findings confirmed that the Power law (PL) model was the best fit to explain the flow behaviour of these gums solutions. The consistency coefficient (k-index) of BSG, LSG, and WSG solutions significantly (p < 0.05) reduced from 0.108 to 0.017 Pa.sn, 0.143 to 0.033 Pa.sn, and 0.034 to 0.014 Pa.sn with increasing sonication time from 0 to 20 min, respectively. The flow behaviour index (n-index) of the gums solutions increased with increasing sonication time. By applying ultrasound, the lightness (L⁎) and blueness/yellowness (b⁎) indexes of the solutions were increased, and the greenness/redness (a⁎) index was reduced.

Synthesis and Performance Evaluation of a Novel High-Temperature-Resistant Thickener.

Successful exploitation of carbonate reservoirs relies on the acid-fracturing process, while the thickeners used in this process play a key role. It is a common engineering problem that thickeners usually fail to function when used in high-temperature environments. Until now, no research has ventured into the field of synthesizing thickeners which can be effectively used at ultra-high temperatures up to 180 °C. In our current study, a novel high-temperature-resistant polyacrylamide thickener named SYGT has been developed. The thermal gravimetric analysis (TGA) reveals that SYGT is capable of withstanding temperatures of up to 300 °C. Both our scanning electron microscopy (SEM) and rheological analysis demonstrate that the SYGT exhibits excellent resistance to both temperature and shear. At 180 °C, the viscosity of the SYGT aqueous solution is no lower than 61.7 mPa·s at a 20% H+ concentration or high salt concentration, and the fracture conductivity of the thickened acid reaches 6 D·cm. For the first time, the influence of the polymer spatial network's structural parameters on the viscosity of polymer solutions has been evaluated quantitatively. It was discovered that the length and surrounding area of the SNS skeleton have a synergistic effect on the viscosity of the polymer solution. Our experiments show that SYGT effectively reduces the acid-rock reaction rate and filtration loss under harsh working conditions such as high temperature, strong shear, high salinity, and a high concentration of acid. The synthesized acid-fracturing thickener (SYGT) has wide application potential in the development of carbonate reservoirs under high-temperature conditions.

Prediction of Dynamic Viscosity and Sensitivity Study of Potassium Amino-Acid Salt Aqueous Solutions by an Artificial Neural Network According to the Structure

Prediction of Dynamic Viscosity and Sensitivity Study of Potassium Amino-Acid Salt Aqueous Solutions by an Artificial Neural Network According to the Structure

ACOUSTIC AND THERMODYNAMICS STUDY OF AQUEOUS DEXTRAN: AN ULTRASONIC ANALYSIS

The acoustical investigation of molecular interaction has been performed from the measurement parameters of ultrasonic velocity (U), density (ρ) and viscosity (η) of aqueous dextran solution at different temperatures. The thermodynamic and other allied pa

Volumetric and viscometric properties of aqueous choline chloride + methyldiethanolamine deep eutectic solvents

Amine-based deep eutectic solvents have the advantages of easy preparation, extremely low vapor pressure, stable biodegradation and high CO2 loading, which has become the most potential CO2 absorbent. In this work, the amine-based functionalized DES of choline chloride + methyldiethanolamine with different molar ratios were successfully prepared, and the densities and viscosities of DES aqueous solutions were measured from 303.15 K to 333.15 K. The effects of DES composition, water content and temperature on the excess molar volume, partial molar volume, apparent molar volume, limiting partial molar volume and viscosity deviation were investigated. The hydration and intermolecular interaction in DES solution were analyzed. The critical concentration of water in solution was determined under the premise of maintaining DES hydrogen bond network.

Comparative Evaluation of the In Vitro Cytotoxicity of a Series of Chitosans and Chitooligosaccharides Water-Soluble at Physiological pH.

Chitosans (CS) have been of great interest due to their properties and numerous applications. However, CS have poor solubility in neutral and basic media, which limits their use in these conditions. In contrast, chitooligosaccharides (COS) have better solubility in water and lower viscosity in aqueous solutions whilst maintaining interesting biological properties. CS and COS, unlike other sugars, are not single polymers with a defined structure but are groups of molecules with modifiable structural parameters, allowing the adaptation and optimization of their properties. The great versatility of CS and COS makes these molecules very attractive for different applications, such as cryopreservation. Here, we investigated the effect of the degree of polymerization (DP), degree of N-acetylation (DA) and concentration of a series of synthesized CS and COS, water-soluble at physiological pH, on their cytotoxicity in an L929 fibroblast cell culture. Our results demonstrated that CS and COS showed no sign of toxicity regarding cell viability at low concentrations (≤10 mg/mL), independently of their DP and DA, whereas a compromising effect on cell viability was observed at a high concentration (100 mg/mL).

Chain-like Structures Facilitate Li+ Transport in Concentrated Aqueous Electrolytes: Insights from Ultrafast Infrared Spectroscopy and Molecular Dynamics Simulations.

Highly concentrated aqueous electrolytes have attracted attention due to their unique applications in lithium ion batteries (LIBs). However, the solvation structure and transport mechanism of Li+ cations at concentrated concentrations remain largely unexplored. To address this gap in knowledge, we employ ultrafast infrared spectroscopy and molecular dynamics (MD) simulations to reveal the dynamic and spatial structural heterogeneity in aqueous lithium chloride (LiCl) solutions. The coupling between the reorientation dynamics of the extrinsic probe and the macroscopic viscosity in aqueous LiCl solutions was analyzed using the Stokes-Einstein-Debye (SED) equations. MD simulations reveal that the Cl- and Li+ form chain-like structures through electrostatic interactions, supporting the vehicular migration of Li+ through the chain-like structure. The concentration dependent conductivity of the LiCl solution is well reproduced, where Li(H2O)2+ and Li(H2O)3+ are the dominant species that contribute to the conduction of Li+. This study is expected to establish correlations between ion pair structures and macroscopic properties.

Influence of isopropanol on the rheological behavior of wormlike micelles

Abstract The influence of replacing water with isopropanol (IP) on the rheological properties of aqueous solutions containing wormlike micelles (WLMs) prepared by mixing cetyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal) at 25 °C was investigated. Viscosity of CTAB aqueous solutions exhibits two maxima and one minimum with increasing amounts of NaSal, consisting of entangled WLMs. When water is replaced by increasing amount of IP, the viscosity maxima and the minimum changes drastically. The elastic plateau modulus G° of these solutions remains almost the same with increasing IP contents (up to ∼5 wt%), whereas their relaxation time changes drastically. Critical micelle concentration (CMC) of CTAB has increased with further IP addition, indicating an increase in the micellar hydrophilicity. For WLMs at minimum viscosity, increasing addition of IP (&gt;5.0 %) to WLMs at maximum and minimum viscosities, leads to a drastic decrease in the elastic modulus G°, indicating the formation of smaller micellar aggregates. The influence of IP as a co-solvent on the WLMs rheological properties is also compared to that of glycerol and 1,3 butanediol (1,3 BD) for the same NaSal/CTAB viscoelastic system.

Critical Analysis of Published Physical Property Data for Aqueous Potassium Hydroxide. Collation into Detailed Models for Alkaline Electrolysis

Physical properties of aqueous KOH solutions are crucial to the design and operation of alkaline electrolyzers but have been scarcely and sometimes unreliably reported. Obtaining published data for various properties currently requires time-consuming searches and subsequent interpretation, interpolation, and extrapolation. This work collates and critically analyzes published data for a range of physical properties relevant to alkaline electrolysis, including the density, viscosity, conductivity, surface tension, oxygen/hydrogen solubility, oxygen/hydrogen diffusivity, and water vapor pressures of aqueous KOH solutions, as a function of temperature, KOH molarity, and pressure. Correlation functions, in the form of excel spreadsheets, have been developed to allow interpolation of the most reliable data and computation of desired quantities at specific temperatures, pressures, and KOH concentrations. Composite models incorporating these properties have been developed for automated computation of (i) diffusive gas crossover and (ii) gas production volumes, including (iii) water vapor content, and associated (iv) dissolved gas concentrations in the liquid electrolyte, as a function of KOH concentration, temperature, pressure, current density, and separator thickness and porosity. These spreadsheets are provided in the Supporting Information, as tools and reference points for researchers and practitioners in alkaline electrolysis.

Hydration Numbers of Polyethylene Glycols Based on a New Viscosity Model

AbstractDue to the high solubility in water and the structural compatibility of polyethylene glycol with water molecules, it is a good model system for studying the mechanisms of interaction between water and biopolymers. The behavior of biopolymers in living organisms strongly depends on the hydration of macromolecules in the aquatic environment. In this work the effective hydration numbers of polyethylene glycols are determined using a new viscosity model developed for electrolytes and experimental data on the viscosity of dilute aqueous solutions of polyethylene glycols (300–35000). The calculated hydration numbers are in good agreement with the literature data and increase with increasing molecular mass of polyethylene glycol: as the molecular mass increases, starting from a molecular mass of 1000, the chain begins to fold in on itself, forming segment‐segment interactions, trapping additional, more loosely bound water between the segments. Based on the dependence of the intrinsic viscosity on the molecular mass according to the Mark‐Houwink equation, it is shown that PEGs are the flexible polymers and highly soluble in water.