Glycerol Mass Fraction Research Articles

Temperature swing solvent extraction for salt and glycerin separation from wastewater

A relatively novel temperature-swing solvent extraction (TSSE) technology was investigated for the separation of salt and glycerol from high-salt wastewater containing glycerol. Diisopropylamine (DIPA) was employed as the solvent for successfully treating ultrahigh-salinity wastewater. Experimental results indicated that the salt removal rate of TSSE technology reached up to 93.86% in saturated brine containing 10.00 wt% glycerol. After five cycles of solvent recovery, the salt removal rate remained at 84.55%. Additionally, when the glycerol mass fraction in saturated brine was 80.00 wt%, the water recovery rate of TSSE technology was 60.27%, with a salt removal rate of 92.88%. The study also analyzed the mechanism of TSSE, revealing that the difference in solubility between DIPA and NaCl in water is crucial for achieving TSSE. The unique capability of TSSE technology in treating high-salt wastewater containing organics was highlighted, achieving not only effective salt removal but also glycerol concentration. The findings of this research not only demonstrate the remarkable effectiveness of TSSE technology in addressing high-salt wastewater containing glycerol but also forecast its promising outlook and immense potential for widespread adoption in various industrial wastewater treatment sectors.

Near-wall depletion and layering affect contact line friction of multicomponent liquids

The main causes of energy dissipation in micro- and nanoscale wetting are viscosity and liquid-solid friction localized in the three-phase contact line region. Theoretical models predict the contact line friction coefficient to correlate with the shear viscosity of the wetting fluid. Experiments conducted to investigate such correlation have not singled out a unique scaling law between the two coefficients. We perform molecular dynamics simulations of liquid water-glycerol droplets wetting silicalike surfaces, aimed to demystify the effect of viscosity on contact line friction. The viscosity of the fluid is tuned by changing the relative mass fraction of glycerol in the mixture and it is estimated both via equilibrium and nonequilibrium molecular dynamics simulations. Contact line friction is measured directly by inspecting the velocity of the moving contact line and the microscopic contact angle. It is found that the scaling between contact line friction and viscosity is sublinear, contrary to the prediction of molecular kinetic theory. The disagreement is explained by accounting for the depletion of glycerol in the near-wall region. A correction is proposed, based on multicomponent molecular kinetic theory and the definition of a rescaled interfacial friction coefficient. Published by the American Physical Society 2024

Tetragonal Nanosized Zirconia: Hydrothermal Synthesis and Its Performance as a Promising Ceramic Reinforcement

In this study, we produced zirconia nanoparticles with a pure tetragonal phase, good dispersion, and an average particle size of approximately 7.3 nm using the modified hydrothermal method. Zirconium oxychloride (ZrOCl2-8H2O) was used as zirconium source, while propanetriol was used as an additive. The influence of propanetriol content, sonication time, hydrothermal temperature, and type of dispersant on the physical phase and dispersibility of zirconia nanoparticles was investigated. Monoclinic zirconia was found to completely transform into a tetragonal structure when the mass fraction of glycerol was increased to 5 wt%. With the increase in the mechanical stirring time under ultrasonic conditions, the size distribution range of the prepared particles became narrower and then wider, and the particle size became first smaller and then larger. Ultrasonic and mechanical stirring for 5 min had the best effect. When comparing the effects of different dispersants (PEG8000, PVP, and CTAB), it was found that the average particle size of zirconia nanoparticles prepared with 0.5 wt% PVP was the smallest. Furthermore, by adding different concentrations of pure tetragonal phase nanozirconia to 3Y-ZrO2 as reinforcement additives, the bending strength of the prepared ceramics increased first and then decreased with increasing addition amounts. When the amount of addition was 1 wt% and the ceramic was calcined at 1600 °C, the flexural strength of the ceramic increased significantly, which was about 1.6 times that of the unadded ceramic. The results are expected to provide a reference for the reinforcement of high-purity zirconia ceramics.

Design of Model Fluids for Flow Characterization Experiments Involving Mixing of Dissimilar Fluids—Refractive Index Matching and Physical Properties

Aqueous solutions of glycerol are widely used as model fluids in flow phenomena experiments. The design of these experiments involves the description of the physical properties of liquids and the refractive index matching using a salt, i.e., calcium chloride. The first part of this paper describes the physical properties of aqueous solutions of glycerol. Refractive index, viscosity, and density were measured for a mass fraction of glycerol in a range from 0 to 1 and compared to the data in the literature. In the second part, calcium chloride was added to aqueous solutions of glycerol, and the variations of density, viscosity, and refractive index with the mass fraction of calcium chloride were reported, which is a new contribution to literature. The main novelties of this work are (1) the development and validation of a set of equations to predict the rheological and physical properties of model fluids for flow studies involving dissimilar fluids; (2) the introduction of an algorithm to match the refractive index of fluids using calcium chloride. The model fluids are designed for large throughput experiments of industrial units, and low-cost solutions were considered. A Matlab script is provided that enables the easy implementation of this method in other works.

Visualization of Local Concentration and Viscosity Distribution during Glycerol-Water Mixing in a Y-Shape Minichannel: A Proof-of-Concept-Study.

The work presents an efficient and non-invasive method to visualize the local concentration and viscosity distribution of two miscible and non-reacting substances with a significant viscosity difference in a microchannel with a Y-shape cell. The proof-of-concept setup consists of a near-infrared (NIR) camera and cost-effective dome lighting with NIR light-emitting diodes (LED) covering the wavelength range of 1050 to 1650 nm. Absorption differences of glycerol and water and their mixtures with a mass fraction of glycerol from 0 to 0.95 were analyzed in the NIR spectral area. The resulting measurement images were converted in a concentration profile by using absorbance calculated with Lambert–Beer law. A linear behavior between the concentration and the absorption coefficient is demonstrated. The result of local concentration in mass fraction was used to determine the local viscosity and illustrated as distribution images. By variating the fluid parameters, the influences of the highly different original viscosities in the mixing procedure were investigated and visualized.

Correlation between the toroidal modes of an elastic sphere and the viscosity of liquids

Vibration characteristics of elastic nanostructures embedded in fluid medium have been used for biological and mechanical sensing and also to investigate materials and mechanical properties. An analytical approach has been developed in this paper to accurately predict toroidal vibrations of an elastic nanosphere in water–glycerol mixture. The Maxwell and Kelvin–Voigt models are used to describe the viscoelasticity of this fluid. The influence of key parameters such as glycerol mass fraction, sphere radius, and angular mode number are studied. We demonstrate that the sphere radius plays a significant role on the quality factor. Results also highlight three behavior zones: viscous fluid, transition, and elastic solid. In addition, these investigations can serve as benchmark solution in design of liquid sensors.

Solubility and Physical Properties of Calcium Sulfate Dihydrate in NaCl and Glycerol Aqueous Solution at 303.15, 323.15, and 343.15 K

The solubility of calcium sulfate dihydrate (CaSO4·2H2O) was measured in NaCl and glycerol aqueous solution with the mass fraction of glycerol 0–80% and molality of NaCl 0–6 m in the temperature ra...

Physical, Chemical, Thermal and Microstructural Characterization of Edible Films from Mechanically Deboned Chicken Meat Proteins

Mechanically deboned chicken meat protein concentrate (CMPC) was mixed with 30, 40 and 50% glycerol to produce films and physical, thermal, chemical, morphological and microstructural properties of films were characterized. The apparent porosity of films increased with increasing glycerol content which was due to the increase of free volume in film matrix (P < 0.05). The higher the apparent porosity, the greater the water vapor and oxygen permeability of films were (P < 0.05), which means gas molecules are permeating through pores. Puncture strength of films decreased as glycerol concentration increased, whereas puncture deformation was increased (P < 0.05). Lower glass transition temperature (Tg) observed as glycerol concentration increased, and Tg values of films were well fitted to Gordon-Taylor model as a function of glycerol mass fraction. Higher glycerol concentrations led to decrease of onset temperatures of weight losses, while weight loss increased. Infrared spectra of films showed similar backbone structure, but increasing glycerol concentration affected to peak intensity around 1000–1100 cm−1. All films had low percentage of degree of crystallinity. CMPC films showed lower contact angle than 65° and all films had hydrophilic surfaces. The surface morphology of films showed that films plasticized with 40% glycerol had the lowest roughness value (P < 0.05). Micrographs of films also showed porous surface structure as glycerol concentration increased, and these images supported the results of porosity, mechanical and barrier properties of films. It can be concluded from these results that glycerol at 40% concentration showed the best results when compared with the other two concentrations.

Chemically Induced Flow in Contaminated Unsaturated Soil

Core Ideas Chemically induced water movement in unsaturated sand is due mainly to matric gradients. A secondary cause is osmotic gradients. Physico‐chemical (matric) and osmotic effects were included in Richards’ equation. Mechanistic modeling and thermodynamic analyses support results on net flow direction. Sensitivity analysis indicates hydraulic parameters as the main contributors to observations. Laboratory experiments and numerical modeling were conducted to assess the effects of glycerol concentration gradients on water flow through an unsaturated loamy sand (Yellow bush sand, Australia) at 46% glycerol mass fraction and 12.5% volumetric water content. When the contaminated and uncontaminated experimental soil sections were placed into contact, two opposite mechanisms were found to drive the flow: (i) the matric potential gradient affected by concentration‐dependent surface tension, viscosity, and density repelled contaminated water; and (ii) the osmotic potential gradient had an opposite effect. Experiments demonstrated that the tested sand did not exhibit the complete semipermeable characteristic necessary to induce pure osmotic flow. Rather, physicochemical effects caused by dissolved glycerol were more relevant for water flow than those induced by the osmotic potential. We confirmed our experimental finding by numerical modeling that explicitly accounted for these effects compared with our experiments and earlier experiments conducted with 7% butanol–water mixtures as benchmarks. Our results were finally confirmed by a thermodynamic interpretation of matric and osmotic potentials. Experiments suggest that a rapid transient condition occurred on the first day and that equilibrium was recovered only after &gt;60 d. The results support the hypothesis that chemically induced water flow in the vadose zone is contributed mainly by matric and only secondarily by osmotic effects, which have displaced 3 to 10% water during the initial transient condition. Predictive tools of contaminant hydrology in unsaturated soil may have to account for the osmotic effects in particular applications that involve soil with high osmotic efficiency.

A numerical and experimental analysis of the methodology of thermal conductivity measurements in fluids by concentric cylinders

A study of thermal conductivity measurements of fluids, using the technique of steady-state heat transfer in concentric cylinders, is presented. In order to evaluate the effect of convective flow on the measured value of conductivity, numerical results, which were obtained using computational fluid dynamics (CFD) in three dimensions, are compared with experimental data and analytical results of temperature profiles. This latter was obtained considering the hypothesis of heat transfer mechanism being entirely diffusive and solely in the radial direction. An experimental design was proposed aiming to analyze the effects of glycerol mass fraction (0%, 50 and 100%), annuli size (2.525, 4.525 and 6.525 mm) and heat rate (5, 10 and 15 W) in the formation of convective streamlines. The ratio between effective and absolute conductivities (kef/k) was used as a response to evaluate the convection intensity. The results were compared with empirical equations that correlate the ratio kef/k with the dimensionless numbers of Prandtl and Rayleigh, which are in the rate 4.37 ≤ Pr ≤ 3.8 × 103 and 9.0 ≤ Ra ≤ 4.4 × 104. An evaluation of the accuracy in measuring kef is showed based on the simulated data of temperature profiles in the axial, radial and angular directions.

Vapor–Liquid Equilibrium of Water + Ethanol + Glycerol: Experimental Measurement and Modeling for Ethanol Dehydration by Extractive Distillation

The present work aims at establishing reliable activity coefficient model for vapor–liquid equilibrium (VLE) of the system water + ethanol + glycerol, with an emphasis on the application in ethanol dehydration by extractive distillation. New experimental data were reported for ternary VLE at 100 kPa, boiling temperature of water + glycerol at 101.33 kPa, and infinite dilution activity coefficient of water and ethanol, respectively, in glycerol at five temperatures of 313.15 K to 393.15 K. The NRTL equation was used for the modeling. For extending the composition and temperature range of data source, literature data of binary VLE of water + ethanol, infinite dilution activity coefficients of water + ethanol, and excess enthalpies of water + glycerol were also used for optimization of the NRTL parameters. The correlation showed that the azeotrope of water + ethanol can be removed at a glycerol mass fraction of 0.0902. The experimental results were compared graphically with those of calculations, showing good agreement. Comparisons were also presented for experimental results and correlations available in the literature.

Diffusion-viscosity decoupling in supercooled glycerol aqueous solutions.

The diffusion of ferrocene methanol in supercooled glycerol-water mixtures has been measured over a wide viscosity range, which allowed analyzing the composition dependence of the Stokes-Einstein breakdown (diffusion-viscosity decoupling). The observed decoupling exhibits a common behavior for all studied compositions (glycerol mass fractions between 0.7 and 0.9), determined by the reduced temperature (T/Tg) of the mixtures. This result differs from that reported previously for the diffusion of glycerol in its aqueous solutions, where the reduced temperature for the decoupling decreases with increasing water content. We conclude that the contradictory results are only apparent, and they can be explained by the use of inconsistent extrapolated values of the viscosity of the glycerol-water mixtures in the supercooled region.

Experimental Measurement and Modeling of Ternary Vapor–Liquid Equilibrium for Water + 2-Propanol + Glycerol

Isobaric vapor–liquid equilibrium (VLE) data for the ternary system water + 2-propanol + glycerol are reported at 100 kPa. The ternary VLE data, together with literature values of binary VLE and activity coefficients at infinite dilution for water + 2-propanol, were correlated by the NRTL activity coefficient model. The correlation appears to be satisfactory for all the data. The experimental results were compared graphically with those of calculations, showing good agreement. With the addition of glycerol, the azeotrope of water + 2-propanol can be removed at a glycerol mass fraction of 0.229. Glycerol is a potentially effective entrainer for dehydration of 2-propanol by extractive distillation.

Viscosity of supercooled aqueous glycerol solutions, validity of the Stokes–Einstein relationship, and implications for cryopreservation

The viscosity of supercooled glycerol aqueous solutions, with glycerol mass fractions between 0.70 and 0.90, have been determined to confirm that the Avramov–Milchev equation describes very well the temperature dependence of the viscosity of the binary mixtures including the supercooled regime. On the contrary, it is shown that the free volume model of viscosity, with the parameters proposed in a recent work (He, Fowler, Toner, J. Appl. Phys. 100 (2006) 074702), overestimates the viscosity of the glycerol-rich mixtures at low temperatures by several orders of magnitude. Moreover, the free volume model for the water diffusion leads to predictions of the Stokes–Einstein product, which are incompatible with the experimental findings. We conclude that the use of these free volume models, with parameters obtained by fitting experimental data far from the supercooled and glassy regions, lead to incorrect predictions of the deterioration rates of biomolecules, overestimating their life times in these cryopreservation media.

Relaxation and antiplasticization measurements in trehalose–glycerol mixtures – A model formulation for protein preservation

We utilize dielectric relaxation spectroscopy for the quantitative characterization of antiplasticization of glassy-trehalose by glycerol. The high frequency Johari–Goldstein relaxation time ( τ) was obtained by analyzing the complex permittivity data in terms of the distribution function of relaxation times and a regularization technique. We analyzed the dielectric spectrum without prior assumptions about a spectral function and the number of the relaxation processes. The ratio of τ values for the mixture and pure trehalose, an antiplasticization factor ( Θ), is found to provide a useful measure of the extent of antiplasticization. We observe that increasing the glycerol mass fraction ( x w ) at fixed temperature increases τ, extending antiplasticization until a temperature dependent critical plasticization concentration is reached. At a fixed concentration, we find an antiplasticization temperature at which antiplasticization first occurs upon cooling. At a temperature of 293 K the antiplasticization factor peak value is about 1.6 when x w of glycerol is about 0.24. At 323 K a mild antiplasticization maximum occurs when x w decrease to about 0.05. Above 323 K, Θ < 1, glycerol plasticizes trehalose, thus the antiplasticizing effect apparently no longer exists. The antiplasticization factor that we describe in terms of Arrhenius functions is a convenient predictive model to characterize antiplasticization in glassy sugar formulations and other glass-formers.

Combined effect of water and KOH on rapeseed oil methanolysis

This paper deals with the effect of water and catalyst (KOH) amount on the quantity and quality of transesterification products of rapeseed oil by methanol, the methyl ester phase (i.e. yield, conversion), and the side-product, the glycerol phase (i.e. density, viscosity, the mass fraction of glycerol, esters, soaps). The dependencies were described by statistical models. The transesterification was carried out at constant reaction conditions (90 min reaction time, 400 rpm, 60 °C). Twelve experiments with the independent factors, amount of potassium hydroxide (0.65–0.9 mg per gram of oil) and total amount of water (0.24–1.42 mg per gram of oil) naturally present in the reaction components or formed by the neutralisation reaction of free fatty acids and of added water. The data were analyzed by linear regression with respect to regression triplet (complex critical analysis of the model, data and regression method). The analysis resulted in a set of linear and/or quadratic models consisting of statistically proven terms at a statistical significance level of 0.05 and demonstrated that ester in the glycerol phase increases with increasing amount of soaps.

Optimal Separation of Glycerol and Methyl Oleate via Liquid−Liquid Extraction

To meet the ASTM D-6751-02 Standard for biodiesel, impurities, particularly glycerol, must be reduced to acceptable levels. Liquid−liquid extraction (i.e., solvent partitioning) is commonly used to achieve this standard. Evaluation of the technical feasibility of a single-stage mixer−settler liquid−liquid equilibrium process to separate glycerol and methyl oleate (as a model for biodiesel) was carried out based on the following criteria: (a) a volume ratio of the liquid phases close to 1:1, (b) a high recovery of biodiesel, (c) a short residence time of the liquid phases in the settler, and (d) achievement of the ASTM Standard for glycerol mass fraction of 0.0002 or less. Eight liquid−liquid extraction processes using different combinations of three potential solvents, hexane, methanol, and water, were studied. All data for the optimal compositions of each solvent system were obtained by calculations using the UNIFAC activity coefficient model, and no experimental measurements were done. Extraction using multisolvent systems containing hexane, methanol, and water were found to be technically feasible and gave the best results.

Medium Effects and Determination of Primary and Secondary Standards for pH Measurements in (Glycerol + Water) Solvent Media at Normal and Subzero Temperatures, With Characterization of Appropriate Salt Bridges

The primary and the secondary standards for the pH measurements in solvent media Z = (glycerol [G] + water [W]) at glycerol mass fractions wG up to 0.4 and at temperatures from −10 °C to +40 °C have been determined in compliance with the IUPAC criteria. To this purpose, Harned’s reversible cell {Pt|H2|Primary Buffer + KCl in Z|AgCl|Ag|Pt} and Baucke’s nonreversible cell {Pt|H2|Buffer at pHPS in Z|Salt Bridge in Z|Buffer at pHSS in Z|H2|Pt} were used, respectively. As a result, three primary standards (based on the “carbonate”, the “equimolal phosphate”, and the “phthalate” buffers) and three secondary standards (based on the “tetroxalate”, the “tartrate”, and the “unequimolal phosphate” buffers) are now available. Their internal consistency was ascertained through the linear pH dependence of the voltage of the cell {Pt|H2 |Buffer at pHPS [or pHSS] in Z|NH4Cl Bridge in Z|Reference Electrode}. These acquisitions enable the user to perform routine pHX measurements by the regular operational cell {Reference E...

Numerical evaluation of two-fluid mixing in a swirl micro-mixer *

A collaborative investigation of two-fluid mixing in a swirl micro-mixer was carried out by the Shanghai Jiao Tong University and the Tokyo Denki University. Pure water and a mixture of glycerol and water were separately injected into branch channels and they were subsequently mixed in the central chamber. The two-fluid flow pattern was numerically modeled, in which the dependence of the mixture viscosity and density on the mass fraction of glycerol in the mixing fluid was carefully taken into consideration. The mixing performance of the two fluids was evaluated by varying the Reynolds numbers and the mass fractions of glycerol in water. The mixing process was extensively analyzed using streamline maps and contour plotting distributions of pressure and glycerol concentration. The numerical results show that the acceptable uniformity of mixing at Re= 0.1 is primarily attributed to the time-consuming molecular diffusion, whereas the cost-effective mixing at Re> 500 was obtained because of the generation of the swirling flow. The increasing mass fraction of glycerol in water was found to attenuate the mixing performance. The preliminary microscopic visualization of the two-fluid mixing at Re=1300 demonstrated the consistence with the numerical results.

Solubility of Valdecoxib in the Presence of Glycerol, Propylene Glycol, and Poly(ethylene glycol) 400 at (298.15, 303.15, and 308.15) K

This study investigated the solubilization of valdecoxib in aqueous solutions of glycerol, propylene glycol, and poly(ethylene glycol) 400 at (298.15, 303.15, and 308.15) K. The analysis of valdecoxib was carried out by UV spectral measurements at λ max of 204 nm. The solubility of valdecoxib increased with increasing mass fraction of glycerol, propylene glycol, and poly(ethylene glycol) 400 at (298.15, 303.15, and 308.15) K. For poly(ethylene glycol) 400 + water mixtures, the solubility of valdecoxib was higher when compared to the glycerol + water and propylene glycol + water mixtures. The solubilization power of glycerol, propylene glycol, and poly(ethylene glycol) 400 at (298.15, 303.15, and 308.15) K was 1.1, 1.5, and 1.8; 2.6, 2.8, and 2.9; and 3.0, 3.5, and 3.9, respectively.