Solvent Mass Fraction Research Articles

Non-Invasive, Continuous, Quantitative Detection of Solvent Content in Vacuum Tray Drying

A non-invasive capacitance instrument was embedded in the base of a vacuum-drying tray to monitor continuously the residual amount of solvent left in a pharmaceutical powder. Proof of concept was validated with Microcrystalline Cellulose laced with water, as well as water/acetone mixtures absorbed in a spray-dried Copovidone powder. To illustrate the role of impermeability of the base, we derive a model of vapor sorption that reveals the existence of a kinetic limit when solids are thinly spread, and a diffusion limit with greatly diminished effective diffusivity at large powder thickness. By monitoring the residual solvent content of powders, this new in situ technique offers advantages over indirect methods like mass spectrometry of vapor effluents, but without complications associated with probe fouling. To prescribe design guidelines and interpret signals, we model the electric field shed by the probe when a powder holds variable solvent mass fraction in the vertical direction.Graphical abstract

Application of Choline Chloride - Ethylene Glycol Deep Eutectic Solvent for the Extraction of Monocylclic Aromatic Hydrocarbon Contaminants from Soil

Abstract Monocyclic aromatic hydrocarbons like Benzene, toluene, ethylbenzene and xylene (BTEX) are among environmental pollutants that are considered among chemicals of concern. They are often found in industrial effluents, which when discharged into farmlands end up contaminating the soils. Such happenings warrant the remediation of the soil for environmental sustainability. Solvent extraction, prominent among the techniques employed for this remediation, is limited by the type of solvent used, as volatile organic solvents end up producing secondary pollutants. Various kinds of green solvents like Ionic Liquids (ILs) and Deep Eutectic Solvents (DESs) have been used in this technique as replacements for the conventional ones. In this study, DES made from choline chloride and ethylene glycol in the ratio of 1:2 was synthesized, characterized and used for the remediation of soils contaminated with monocyclic aromatic hydrocarbons (BTEX). Response surface methodology was employed to model and optimize the extraction process. Extraction efficiencies of 76.25, 79.04, 81.93 and 78.66% were obtained for benzene, toluene, ethylbenzene and xylene in a single stage extraction at optimum condition of 45 minutes, 0.841 and 440 rpm for extraction time, solvent mass fraction and mixing rate respectively. Further studies on the solvent regeneration and reuse were conducted. The findings showed that the solvent has capacity to perform effectively in two (2) successive extraction cycles without regeneration, and can undergo up to five (5) cycles upon regeneration without significant loss in its extracting ability. These studies show the possibility of remediating soils contaminated with BTEX using DES under mild extraction conditions.

Microstructures and properties of PVDF membranes: effect of the solvent

The polyvinylidene fluoride (PVDF) membranes were synthesized using immersion precipitation technique. The effect of four solvents, N, N-dimethyl formamide (DMF), N, N-dimethylacetamide (DMAC), N-methyl-2-pyrrolidone (NMP), and dimethyl sulfoxide (DMSO) on the water flux and beef serum albumin (BSA) rejection efficiency was reported. The structure and morphology of PVDF membranes were studied using Scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and water contact angle measurements. The cross-section of a membrane formed in a DMF as a solvent exhibit a spongy/fingerlike hybrid structure, while DMSO favors the formation of more porous structure. The increase in the solvent mass fraction facilitates liquid phase separation and solution casting, and changes the structure of PVDF membrane from denser, bicontinuous structure to a looser, stacked structure. Moreover, the results revealed that the properties of PVDF membranes sub-layer are controlled by the diffusion rate of the nonsolvent. The membrane with the best performance was prepared using 80% DMF (mass fraction) as a solvent, and it reached water flux of 66 L·m−2·h−1, and 91.53% BSA rejection efficiency.

Performance of Some Novel Mixed Solvents as Entrainers for Separation of Water and Acetonitrile

Performance of some novel mixed solvents as entrainers was tested for acetonitrile dehydration by extractive distillation. The mixed solvents are composed of ethylene glycol (EG) and choline chloride (ChCl) (EG + ChCl 8:1, EG + ChCl 4:1, EG + ChCl 2:1, and EG + ChCl 4:3), ethylene glycol (EG) and glycerol (EG + glycerol 1:1, EG + glycerol 1:2, EG + glycerol 1:4, and EG + glycerol 1:6), and dimethyl sulfoxide (DMSO) and ChCl (DMSO + ChCl 14:1). Isobaric vapor–liquid equilibrium (VLE) data were measured at 101.3 kPa and at a solvent-free acetonitrile mole fraction of 0.95 for the quaternary systems of water + acetonitrile + EG + ChCl, water + acetonitrile + EG + glycerol, and water + acetonitrile + DMSO + ChCl and for the ternary system of water + acetonitrile + DMSO. The NRTL equation was used for the correlation of the experimental VLE data. For all the three quaternary systems and one ternary system, the mean absolute deviations of equilibrium temperature were no more than 0.33 K, and the mean absolute deviations of water and acetonitrile vapor phase mole fractions were no more than 0.0026 and 0.0047, respectively. The mixed solvent EG + ChCl 4:3, which is also a deep eutectic solvent, showed favorable solvent performance. The azeotrope of water + acetonitrile can be removed at a solvent mass fraction of 0.212 or a solvent mole fraction of 0.104. This amount is less than that of EG (0.367 in mass fraction and 0.227 in mole fraction), EG + glycerol 1:6 (0.341 in mass fraction and 0.195 in mole fraction), and DMSO + ChCl 14:1 (0.266 in mass fraction and 0.153 in mole fraction).

Early stage of delayed coalescence of soluble paired droplets: A numerical study

When two sessile droplets of miscible fluids come into contact, the coalescence process can be significantly delayed owing to the competition between the capillary and Marangoni effects. It is important to reveal the mechanism of the deformation and displacement of the sessile droplets at the early stage of the delayed coalescence, which determines the self-stabilized shape and joint motion of the two droplets later on. In this work, we numerically investigate the early-stage dynamics of the delayed coalescence between two sessile droplets of equal size and laden with aqueous mixtures of different solvent mass fractions. A three-dimensional numerical model is adopted based on lubrication theory and is validated by comparison against previous experimental results. Through simulation, we first showed how the concentration transport is coupled with droplet deformation. Then, we explained the underlying mechanism of delayed coalescence by analyzing the liquid bridge numerically and theoretically. A scaling law for the duration of liquid bridge growth is given and agrees well with the numerical results. Finally, the effects of the solubility on the dynamics are investigated. Our study reveals how the capillary and Marangoni effects dominate the flow during the early stage of the delayed coalesce and thus determine its following behavior.

Effects of drying conditions on the solvent diffusion process during coated fabrics curing

Fabric is a porous fiber material; it is not an impermeable substrate. To study the diffusion mechanism of polymethyl methacrylate (PMMA)/acetone coated glass fiber fabric solvent during curing, a drying model for the coated fabric was proposed based on the heat transfer equation, Fick diffusion equation and the coating solution volume with time relationship equation. This drying model was verified by confocal Raman spectroscopy. The impact of solvent mass fraction, drying temperature and air speed on solvent diffusion during curing was studied using the model. It was shown that the predicted solvent concentrations derived from the model were consistent with the experimental values. This model can be used to quantitatively calculate the solvent concentration at any position and at any time inside the coating film during the drying process. Moreover, it can also predict the curing time and residual solvent concentration required for the coating material to reach drying equilibrium. The fitting equations for solvent concentration, drying temperature, air speed and equilibrium drying time were obtained, which can provide a theoretical guidance for the optimized preparation, performance research and drying conditions of PMMA coated textile materials. The model can also be used for other coating formulations and fabrics, by simply changing the material parameters and geometric dimensions of both the coating solution and fabric.

Effect of Mixed Solvents Containing Ethylene Glycol and Various Salts on the Vapor–Liquid Equilibrium of Water + Methanol + Ethanol

The mixture of water, methanol, and ethanol is frequently produced in the pharmaceutical industry. To separate the mixture by extractive distillation, the selection of entrainer is a crucial step. Entrainer performances of ethylene glycol (EG) and some mixed solvents were evaluated in this work, including EG + KOAc, EG + CaCl2, EG + LiCl, and EG + choline chloride (ChCl). Isobaric vapor–liquid equilibrium data were measured for the quaternary and quinary systems at 101.3 kPa and were modeled by use of the NRTL equation. The effects of EG and the mixed solvents on the relative volatilities of the volatile key components are discussed in relation to the effects on the activity coefficients. Results showed that adding salts into ethylene glycol results in significant improvement of solvent performance. A more rapid decrease in the activity coefficient of water, as well as an increase in the activity coefficient of ethanol, can be observed with the addition of the mixed solvents, resulting in a more rapid increase in the relative volatility of ethanol to water. The mixed solvent EG + ChCl 4:3 showed the best performance, having a value of 5.85 for the relative volatility of ethanol to water at a solvent mass fraction of 0.8.

Influence of Composition Dependent Diffusion Coefficient, Viscosity and Relaxation Time on Evaporative Rayleigh-Bénard-Marangoni Instabilities Induced by Solvent Evaporation in a Polymer Solution

In this study, a linear stability analysis is performed for both monotonic and oscillatory modes within a horizontal polymer solution layer, which solely the solvent evaporates into air. The approach is based on general thermodynamic principles and also on the physics of the gas phase and its interactions with the liquid phase. Due to evaporation, the solvent mass fraction changes and cooling occurs at the liquid-gas interface. This can trigger solutal and thermal Rayleigh-Benard-Marangoni instabilities in the system. For the monotonic mode, the effects of composition dependent diffusion coefficient and dynamic viscosity on the onset of Rayleigh-Benard-Marangoni convection are studied. Moreover, the effect of different total heights of the liquid-gas system on the behavior of convection onset is considered. The results show that a variable diffusion coefficient and a variable viscosity can notably change the onset of instability for a polyisobutylene (PIB)/toluene solution. Our model for the monotonic mode is also satisfactorily compared with an experimental study. For the oscillatory mode, where the relaxation time is also composition dependent, we observe that very thin layers will be susceptible to an oscillatory instability when drying occurs in the system. Finally, an approximate model is derived exploiting the fact that the solutal Marangoni is by far the most dominant instability mechanism here. A negligible difference with respect to the full model confirms the predominance of the solutal Marangoni mechanism.

Isobaric Vapor–Liquid Equilibria for the Quaternary System Water + Ethanol + Ethylene Glycol + Choline Chloride and the Ternary System Water + Ethanol + Choline Chloride at 101.3 kPa

An organic salt choline chloride (ChCl) was introduced in ethylene glycol (EG) for improving the entrainer performance for ethanol dehydration by extractive distillation. The mixed solvent EG + ChCl with molar ratios of 8:1, 4:1, 2:1, and 4:3 were tested through vapor–liquid equilibrium (VLE) measurement for the quaternary system water + ethanol + EG + ChCl at 101.3 kPa. Data were also measured for the ternary system water + ethanol + ChCl. VLE behavior of the quaternary system was modeled successfully using the NRTL equation. The mean absolute deviations for the quaternary data were 0.24 K for equilibrium temperature and 0.0041 for vapor mole fraction of ethanol, while deviations for the ternary data were 0.15 K and 0.0032. As compared with EG alone, the existence of ChCl in the mixed solvent decreases the activity coefficient of water and increases the activity coefficient of ethanol, both leading to the enhancement of the relative volatility of ethanol to water. The azeotrope of water + ethanol can be removed with the addition of EG + ChCl 4:3 at a solvent mass fraction of 0.062, showing favorable entrainer performance for ethanol dehydration by extractive distillation.

High pressure phase behaviour for the CO2 + n-dodecane + 3,7-dimethyl-1-octanol system

In this work, the solute-solute interaction which exist in the CO2 + n-dodecane+ 3,7-dimethyl-1-octanol system was investigated. Solubility data were measured for three mixtures containing solvent free n-dodecane fractions of 0.50, 0.75 and 0.85, between 308 K and 348 K and pressures up to 14.9 MPa, with solvent mass fractions ranging from 0.375 to 0.984, using a static synthetic method. The data revealed significant solute-solute interactions, which resulted in the occurrence of co-solvency in the two n-dodecane rich mixtures. The phase behaviour data of the system was modelled, using the RK-ASPEN model. The modelling results indicated that, with the inclusion of a solute-solute interaction parameter, the fitted model was capable of correlating fairly accurate solubility data, but it can only approximate vapour-liquid-equilibrium data.

Permeation of Toluene into (Polypropylene/Acrylonitrile-co-butadiene Rubber) immiscible blend

This study examines the unsteady permeation process of a solvent through a mixture of two immiscible polymers with a complex dividing interface. The mathematical model consists of three nonlinear PDEs that incorporate the coupling arising between mass transport and the dynamic changes of the blend internal structure. In addition to the solvent mass fraction c, we choose, as additional state variables, the conformation tensor m to characterize the macromolecular chains while the embedded interface is described by a scalar Q and a traceless second-order tensor q respectively for the size and shape anisotropy of the area. We extend the Fick's first law by two new non-Fickian terms. Among the obtained results, we present the transient permeation mass flux profiles of toluene through PP/NBR blend system at different compositions and predict the corresponding time lag.

Microfluidics to determine the diffusive mass transfer of a low viscosity solvent into a high viscosity hydrocarbon

In this work, a microfluidic platform along with X-ray computerized tomography were employed to analyze diffusive mass transfer of a low viscosity solvent (hexane) into a high viscosity hydrocarbon (bitumen). T-shaped microfluidic channels were fabricated to measure the diffusion coefficient in significantly shorter times and lower sample volume compared with traditional methods. Semitransparent nature of bitumen facilitates the application of light transmission imaging during the time and relating intensities to solvent concentration. Diffusion mass transfer was studied with respect to Fickian and Single-File mass transfer mechanisms and corresponding equation was applied to calculate both constant and concentration dependent diffusion coefficients. The accuracy of Fickian mass transfer mechanism was confirmed with calculating values of fitting parameter (i.e. nw) in addition to superimposition of data for both techniques. The optimum values of constant diffusion coefficient for T-shaped microchannel and X-ray technique were 2 × 10−10 and 1.8 × 10−10 m2·s−1, respectively. Concentration dependent diffusion coefficients ranged from 1 × 10−12 to 3.6 × 10−10 m2·s−1 for the experiments that reveal constant mutual diffusion coefficient assumption can result in significantly high errors particularly at low and high solvent mass fractions.

Vapor–Liquid Equilibria for 2-Propanol Dehydration through Extractive Distillation Using Mixed Solvent of Ethylene Glycol and Choline Chloride

The mixed solvent of ethylene glycol (EG) and choline chloride (ChCl) was tested as an entrainer for 2-propanol dehydration by extractive distillation. Isobaric vapor–liquid equilibrium (VLE) data were measured at 101.3 kPa for the quaternary system water + 2-propanol + EG + ChCl. The NRTL equation was used for the modeling of the quaternary VLE. Mean absolute deviations were 0.26 K and 0.0036 for equilibrium temperature and vapor mole fraction of 2-propanol, respectively. As compared with EG alone, the existence of ChCl in the solvent significantly decreases the activity coefficient of water and increases the activity coefficient of 2-propanol, both enhancing the relative volatility of 2-propanol to water. The azeotrope of water +2-propanol can be removed with the addition of the deep eutectic mixture EG + ChCl 2:1 at a solvent mass fraction of 0.157. The mixed solvent may be readily applied in extractive distillation of 2-propanol and water, replacing the frequently used mixed solvent of ethylene glycol and potassium acetate.

On modeling of bitumen/n‐tetradecane mixture viscosity: Application in solvent‐assisted recovery method

AbstractExtremely high viscosity of bitumen is of great challenge in bitumen production, transportation, and processing. Therefore, different techniques such as dilution of bitumen by liquid solvents have been proposed for bitumen viscosity reduction. Accurate prediction of diluted bitumen mixture viscosity is a key parameter in solvent injection during hydrocarbon recovery. In this study, a simple correlation and a model in accordance with adaptive neuro‐fuzzy inference systems joined with particle swarm optimization (ANFIS‐PSO) algorithm have been developed for accurate estimation of bitumen/n‐tetradecane mixture viscosity in comparison to other available mixing rules at different pressures, temperatures, and n‐tetradecane mass fractions. For evaluation of the models efficiency, cumulative frequency test was employed to examine the data frequency over the whole databank. The ANFIS‐PSO model exhibits the best performance with average absolute relative deviation of 2.44% and squared correlation coefficient (R2) of 0.9985. Moreover, it is proved that the suggested correlation has the best practical performance than the Lederer and other studied correlations in this work. In other words, the proposed correlation is easy‐to‐use and also, it is a more straightforward function of pressure, temperature, and solvent mass fraction than other literature correlations. Based on the sensitivity analysis, it is demonstrated that solvent concentration is the most influencing parameter in reducing bitumen viscosity. In accordance to the results of this study, the proposed techniques can serve as robust and reliable tools for efficient estimation of bitumen/n‐tetradecane mixture viscosity.

Thermo‐physical properties of n‐pentane/bitumen and n‐hexane/bitumen mixture systems

The gravity drainage as a result of viscosity reduction is the main governing mechanism of the solvent‐aided thermal bitumen recovery processes. Therefore, the density and viscosity of the diluted or heated bitumen are essential to predict the oil production rate. In this paper, we report thermo‐physical properties of n‐pentane/bitumen and n‐hexane/bitumen mixtures. The density and viscosity of Athabasca bitumen diluted with n‐pentane and n‐hexane were measured at different temperatures (30 to 190 °C), pressures (2 to 8 MPa), and solvent mass fractions (0.05 to 0.5). Various correlations and mixing rules proposed in the literature were examined to calculate the density and viscosity of the diluted bitumen. This study proposes appropriate mixing rules and generalized parameters for predicting the density and viscosity of solvent‐bitumen systems. Our findings will find applications in the design and simulation of heavy oil and bitumen solvent‐aided thermal recovery processes.

Batch Solvent Extraction of Bitumen from Oil Sand. Part 1: Theoretical Basis

A model for flow through a porous medium with variable saturation is presented in this work to predict the volume and flow rate of extracted solvent-diluted bitumen from mineral solids during centrifugal filtration. The numerical method used for solving the flow equation is based on the mass-conservative-modified Picard iteration scheme and the Anderson acceleration algorithm. It is found that bitumen extraction involves filtration and desaturation phases, and the transition between them can be identified from the evolution with time of extracted liquid volume and flow rate. An analytical description of the filtration phase is developed to predict the evolution of the liquid layer thickness above the cake during centrifugation. Numerical and analytical models presented in this work can be used in a fitting procedure to determine hydraulic properties of oil sand cake. Effects of centrifugal force and solvent mass fraction on the predicted fraction of extracted diluted bitumen are investigated.

2-Propanol Dehydration via Extractive Distillation Using a Renewable Glycerol–Choline Chloride Deep Eutectic Solvent: Vapor–Liquid Equilibrium

A renewable deep eutectic solvent, glycerol–choline chloride (molar ratio 2:1), was tested as an entrainer for dehydration of 2-propanol by extractive distillation. Isobaric vapor–liquid equilibrium data for the quaternary system water + 2-propanol + glycerol + choline chloride were measured at 100 kPa. With the addition of the deep eutectic solvent, the azeotrope of water + 2-propanol can be removed at a solvent mass fraction of 0.142, which is much smaller than the minimum solvent mass fraction of 0.229 for glycerol alone. With regard to the relatively low viscosity as compared with glycerol, the deep eutectic solvent may have better performance when used as entrainer for 2-propanol dehydration. The NRTL equation was used for the modeling of the quaternary vapor–liquid equilibrium data. Binary parameters of water + 2-propanol, water + glycerol, and 2-propanol + glycerol were fixed as the same for the system water + 2-propanol + glycerol and were taken from the literature. The correlation appeared to be ...

Simulation of polyimide fibers with trilobal cross section produced by dry-spinning technology

As one type of high performance fibers, polyimide fibers can be prepared from polyamic acid (PAA) solution by dry-spinning technology. The transformation from the precursor of polyamic acid to polyimides via thermal cyclization reaction in the dry-spinning process is a main distinguishing feature, which is very different from other fibers produced by dry-spinning such as cellulose acetate fiber and polyurethane fiber. In this report, the dry-spinning formation of polyimide fibers with trilobal cross section from PAA solution in N,N-dimethylacetamide is simulated via a one-dimensional model based on a viscoelastic constitutive equation, combined with profile degree equation of cross section and imidization kinetics equation. The glass transition temperature, imidization degree and profile degree of the filament along the spinline are predicted by the model, as well as relative parameters such as solvent mass fraction and temperature. As a simulated result, solidification of polyimide fibers take place about 150 cm from the spinneret which is farther than for cellulose acetate fiber (70 cm). Moreover, the final profile degree of fiber is affected by many spinning parameters, such as spinning temperature, surface tension, spinning solution concentration, major, and minor axis length of the spinneret hole. POLYM. ENG. SCI., 55:2148–2155, 2015. © 2015 Society of Plastics Engineers

Volumetric Properties of Athabasca Bitumen + n-Hexane Mixtures

The solvent-assisted bitumen recovery processes, such as vapor extraction (VAPEX) and expanding-solvent steam-assisted gravity drainage (ES-SAGD), are designed on the basis of the drainage of diluted oil at in situ conditions. Thus, the density of oil and its diluted mixtures is required to predict the production rate and cumulative oil recovery. In this study, the density of Athabasca bitumen and its mixtures with hexane at different mass fractions (0.05, 0.1, 0.2, 0.3, 0.4, and 0.5) has been accurately measured. The experiments were taken at temperatures changing from ambient up to 463 K and at pressures up to 10 MPa. The volume change upon mixing for the mixtures was investigated from the experimental results, and the influence of pressure, temperature, and solvent mass fraction on the volume change upon mixing and density was studied. The density data are evaluated by no volume change, excess volume, and effective liquid density calculation methods. It was found that the mixture data are well-predicted using effective liquid densities with an average absolute relative deviation (AARD) of 0.31%.

Kinetics of pure propane and n‐butane desorption from soybean oil

AbstractThis work reports experimental data on the desorption of pure propane and n‐butane from refined soybean oil at low pressures. The desorption parameters investigated were the overall solvent (normally gaseous at ambient conditions) content and solution stirring rate. Solvent mass fraction ranged from 1 to 10 wt% and stirring was studied in the interval between 0 and 200 rpm (equivalent to a Reynolds number 2 × 107). Results showed a fast solvent release from the binary propane–soybean oil system, while a relatively slower liberation was noticed for soybean oil−n‐butane, due possibly to the much smaller solubility exhibited by the former solvent. The experimental information reported in this work may be of great technological relevance, since no desorption data were found in the literature for the systems investigated in this work.