Physicochemical Properties Of Solvents Research Articles

Physicochemical properties of extraction solvents for the advanced recycling of spent nuclear fuel

A comprehensive understanding of solvent physicochemical properties is essential to developing advanced solvent extraction processes, such as Advanced PUREX (Plutonium Uranium Reduction Extraction) and GANEX (Group Actinide Extraction), that can safely and efficiently recycle spent nuclear fuel. The densities, viscosities and surface tensions of binary mixtures of tributyl phosphate (TBP) (0.92–3.66 M) in n-dodecane and N,N-di (2-ethyl hexyl)isobutyramide (DEHiBA) (0.69–2.78 M) in n-dodecane were measured at atmospheric pressure from 278.15 to 333.15 K. Through these measurements, empirical expressions to predict the density and viscosity at any molar composition of these solvents within the studied temperature range were constructed and shown to be in good correlation with all experimental data across the studied variables. The relationship between temperature and viscosity of pure TBP and DEHiBA can be described by the Arrhenius equation for viscosity in the temperature range studied. Surface tension measurements (air-liquid interface) were obtained for varying extractant concentrations between 278.15 and 333.15 K, which showed that DEHiBA acts as a surfactant when mixed with n-dodecane whilst TBP exhibits a higher surface tension than n-dodecane.

Thermodynamic insights into selenium oxyanion removal from synthetic flue gas desulfurization wastewater with temperature-swing solvent extraction.

Temperature-swing solvent extraction (TSSE) is a cost-effective, simple, versatile, and industry-ready technology platform capable of desalinating hypersaline brines toward zero liquid discharge. In this work, we demonstrate the potential of TSSE in the effective removal of selenium oxyanions and traces of mercury with the coexistence of high contents of chloride and sulfate often encountered in flue gas desulfurization wastewater streams. We compare the rejection performance of the two common solvents broadly used for TSSE, decanoic acid (DA) and diisopropylamine (DPA), and correlate those with the solvent physicochemical properties (e.g., dielectric constant, polarity, molecular bulkiness, and hydrophobicity) and ionic properties (e.g., hydrated radii and H-bonding). The results show that TSSE can remove >99.5% of selenium oxyanions and 96%-99.6% of mercury traces coexisting with sulfate (at a sixfold Se concentration) and chloride (at a 400-fold Se concentration) in a synthetic wastewater stream. Compared to diisopropylamine, decanoic acid is more effective in rejecting ions for all cases, ranging from a simple binary system to more complex multicomponent systems with highly varied ionic concentrations. Furthermore, the H-bonding interaction with water and the hydrated radii of the oxyanions (i.e., selenate vs. selenite) along with the hindrance effects caused by the molecular bulkiness and hydrophobicity (or lipophilicity) of the solvents play important roles in the favorable rejection of TSSE. This study shows that TSSE might provide a technological solution with a high deionization potential for the industry in complying with the Environmental Protection Agency regulations for discharge streams from coal-fired power facilities.

Dissolution behavior, thermodynamic and kinetic analysis of malonamide by experimental measurement and molecular simulation

In this study, the solid structure, dissolution behavior, thermodynamic properties and nucleation kinetics of malonamide were explored. Firstly, the Hirshfeld surface analysis and molecular electrostatic potential surface were plotted to reveal the percentage contribution of various intermolecular contacts and location of the strongest hydrogen bond. Next, the solubility of malonamide in 12 solvents was determined by dynamic method at temperatures from 278.15 K to 318.15 K. Four thermodynamic models were applied to analyze solubility results. In addition, the thermodynamic properties were calculated to further analyze and discuss the dissolution behavior of malonamide. Moreover, the physicochemical properties of solvents were explored to express the solvent effects. The results illustrate “like dissolves like”, “mass transfer” and “solvent-solute interaction” rules play the synergistic effects on the dissolution process. The molecular dynamic simulation, including radial distribution function analysis and solvent free energy, was used to further explain the dissolution behavior. At last, the nucleation rate and effective interfacial energy in methanol solvent was measured and calculated to reveal the nucleation behavior.

Predicting Dissolution Kinetics of Tricalcium Silicate Using Deep Learning and Analytical Models

The dissolution kinetics of Portland cement is a critical factor in controlling the hydration reaction and improving the performance of concrete. Tricalcium silicate (C3S), the primary phase in Portland cement, is known to have complex dissolution mechanisms that involve multiple reactions and changes to particle surfaces. As a result, current analytical models are unable to accurately predict the dissolution kinetics of C3S in various solvents when it is undersaturated with respect to the solvent. This paper employs the deep forest (DF) model to predict the dissolution rate of C3S in the undersaturated solvent. The DF model takes into account several variables, including the measurement method (i.e., reactor connected to inductive coupled plasma spectrometer and flow chamber with vertical scanning interferometry), temperature, and physicochemical properties of solvents. Next, the DF model evaluates the influence of each variable on the dissolution rate of C3S, and this information is used to develop a closed-form analytical model that can predict the dissolution rate of C3S. The coefficients and constant of the analytical model are optimized in two scenarios: generic and alkaline solvents. The results show that both the DF and analytical models are able to produce reliable predictions of the dissolution rate of C3S when it is undersaturated and far from equilibrium.

Extractive separation of 4- hydroxybenzoic acid from aqueous solution using nontoxic and conventional solvents

4-hydroxybenzoic acid (4-HBA)1 is potential antidiabetic, anticancer, antioxidant, antifungal, cardioprotective etc. 4-HBA is worth to be recovered as it has bright applications in pharmaceutical, cosmetics and plastic industries. The experiments were performed for the separation of 4-HBA from its aqueous solution using nontoxic solvents; sesame oil, canola oil and conventional solvents; benzene, toluene and petroleum ether. The equilibrium for this physical extraction experiment was evaluated and the parameters like distribution coefficient KD2, % extraction efficiency E%3, partition coefficient P4 and dimerization constant D5 were found and correlated with different physicochemical properties of solvents. The results for KD and E% were found as: sesame oil (0.49,33.24%) > canola oil (0.23,18.85%) > petroleum ether (0.092,8.32%) > toluene (0.09,8.25%) > benzene (0.08,7.49%).

Solid-liquid equilibrium of ropivacaine in fourteen organic solvents: An experimental and molecular simulation study

The solubility of ropivacaine in fourteen pure solvents at 283.15 K to 323.15 K was determined via the gravimetric method and was well correlated with three thermodynamic models, including the Apelblat, λh, and NRTL models. Among all experimental solvents, the solubility of ropivacaine was found to be highest in pure THF and lowest in acetonitrile. In alcohol solvents, the maximum solubility was observed in amyl alcohol followed by 1-butanol, while the minimum value was observed in 1-propanol. The thermodynamic properties of mixing were calculated based on the NRTL equation, indicating that the mixing processes are spontaneous and entropy-driven. In addition, the crystal structure of ropivacaine was obtained and investigated by Hirshfeld surface analysis and molecular electrostatic potential surface analysis. The physicochemical properties of solvents, such as polarity, cohesive energy density and dielectric constant, were analyzed to explain the solid–liquid behavior of ropivacaine. Finally, a molecular dynamics simulation and radial distribution function analysis were performed. The results indicated that ropivacaine could interact with organic solvents via van der Waals interactions, electrostatic interactions, and hydrogen bonding.

Learning the properties of a water-lean amine solvent from carbon capture pilot experiments

Process design and optimization are challenging task not only because of the model formulation and expensive computation but also numbers of physicochemical parameters deducing from experimental data. Numbers of process design employing novel solvents and producing uncommon chemical, therefore, have been suffered from unknown physicochemical properties and resulting process models inherently has high degree of uncertainty. In this work, we developed and assessed a machine learning methodology to estimate parameter uncertainties, specify solvent physicochemical properties, and evaluate the reaction kinetics of a water-lean amine solvent for a CO2 capture process. We integrated two fundamental methodologies to decrease the experimental and computational costs. Gaussian process Bayesian optimization was applied to the pilot-scale tests; in addition, a rigorous process model employing a newly proposed hybrid Bayesian inference was used, which reduces the computational time of sampling. The assessment highlights the Gibbs free energy of the particular electrolyte as the most sensitive parameter to match the process responses. Both water and water-lean amine solvent, K2Sol, were observed to act as dominant bases in the absorption kinetics. Furthermore, most output responses of the process model were located in the 95% confidence interval. Our methodology efficiently incorporates process optimization from past experiments and simultaneously identifies solvent characteristics to build rigorous process models that automatically consider uncertainties.

Solubility and solution thermodynamics of isobutyramide in 15 pure solvents at temperatures from 273.15 to 324.75 K

Being an important synthetic monomer, isobutyramide (IBA) is employed as an intermediate for the synthesis of organic dyes and pharmaceuticals. It is well known that investigation of the solubility behavior of drugs and intermediates has become an extensive research topic in pharmaceutical development. In this work, the solid-liquid equilibrium (SLE) data of IBA in fifteen solvents, including methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, acetonitrile, chloroform, acetone, ethyl formate, methyl acetate, cyclohexanone, cyclopentanone, tetrahydrofuran and 2-butanone was measured with a static gravimetric method with the temperature ranging from 273.15 to 324.75 K under atmospheric pressure. The solubility of IBA increases with the rising temperature in all selected solvents. The ranking of solubility in various solvents is not in accordance with the order of solvent physicochemical properties, namely polarity index, dipole moment, dielectric constant and solubility parameter. The modified Apelblat equation, λh equation, nonrandom two-liquid (NRTL) model and the Wilson model were used to correlate the experimental data. Maximum root-mean-square deviation (RMSD) and relative average deviation (RAD) were 7.157 × 10−3 and 1.80%, respectively. The λh equation presented less effective correlating results compared with other three models. The dissolution properties of IBA, including Gibbs energy (△disG), molar enthalpy (△disH) and molar entropy (△disS) were determined based on the Wilson model and the solubility data. Positive values of the dissolution enthalpy and entropy illustrated that the dissolution process of IBA in selected solvents are endothermic and entropy-driven.

Determining the solubility and understanding the solid-liquid equilibrium behavior of cyhalothric acid in eleven pure solvents

The cyhalothric acid (CTA), an important intermediate for the production of pyrethroids, was selected to obtain its solubility data in eleven pure solvents using gravimetric method from 283.15 K to 323.15 K. Among the alcohol solvents, methanol with the largest polarity has the lowest solubility and tert-butanol has the strongest solubility. Three ester solvents have similar solvency to CTA. The physicochemical properties of solvents and radial distribution function (RDF) analysis based on molecular dynamic (MD) simulation were further employed to interpret the difference of solubility. Moreover, the experimental solubility of CTA in pure solvents was well correlated by modified Apelblat equation, λh equation and the NRTL (nonrandom two-liquid) model, respectively, in which the modified Apelblat equation achieved the best fitting. The mixing properties (enthalpy, Gibbs energy and entropy) were also determined and the results show that mixing process is spontaneous and entropy-driven.

Migration behavior of organic dyes based on physicochemical properties of solvents as background electrolytes in non-aqueous capillary electrophoresis

The migration behavior of organic fluorescent dyes (i.e., crystal violet, methyl violet base, methyl violet B base, rhodamine 6G, and rhodamine B base) in non-aqueous capillary electrophoresis (NACE) was investigated by focusing on the physicochemical properties of various organic solvents [ethanol, methanol, 2-propanol, dimethylformamide (DMF), and dimethyl sulfoxide (DMSO)] in background electrolyte (BGE). Laser-induced fluorescence (LIF) and UV/Vis detectors were employed to observe both the migration time of organic dyes and the electroosmotic flow (EOF) in NACE, respectively. As seen in conventional aqueous BGE, the mobility of EOF in organic solvents tended to rise when the ratio between the dielectric constant and the solvent’s viscosity (ε/η) increased in accordance with Smoluchowski’s equation. However, unlike the ε/η of pure organic solvents, the migration order of dyes changed as follows: methanol (60.0) > DMF (45.8) > ethanol (22.8) > DMSO (23.4) > 2-propanol (9.8). Since the amount of acetic acid added to balance the pH depends on the pKa of each solvent, EOF changed when the difference in the ε/η value was small. This resulted from the inhibition of mobility, and its difference was dependent on the ε/η of BGEs with high ionic strength. In particular, the actual mobility of dyes in DMF showed excellent compliance with the Debye–Hückel–Onsager (DHO) theory extended by Falkenhagen and Pitts, which enabled us to analyze all dyes within 15 min with excellent resolution (Rs > 2.5) under optimum NACE conditions (10 mM sodium borate and 4661 mM acetic acid in 100% DMF, pH 4.5). In addition, the NACE method was successfully applied for analyzing commercially available ballpoint ink pens. Thus, these results could be used to anticipate the migration order of organic dyes in a 100% NACE separation system.

A random forest model for predicting crystal packing of olanzapine solvates

A random forest (RF) classification model obtained from physicochemical properties of solvents and crystal structures of olanzapine has for the first time enabled the prediction of 3-D crystal packings of solvates. A novel solvate was obtained by targeted crystallization from the solvent identified by RF model.

Sol–gel derived nanostructured nickel oxide films: Effect of solvent on crystallographic orientations

Nickel oxide films were deposited onto glass substrates by sol–gel dip coating method using solvents of different polarities without any catalysts, templates or surfactants. Methanol, 1,4-butanediol, ethanol, and 2-propanol were used as solvents. The structural, optical and electrical properties of NiO films were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), UV–visible spectroscopy and Hall effect measurements, respectively. Nickel oxide thin films with cubic phase crystal structure of various preferred orientations were obtained in the different solvents. The XRD results showed that films deposited from solution using higher polar solvents develop a (1 1 1) preferred orientation, while the (2 0 0)-orientated films were obtained using lower polar solvents. The average particle size increases with viscosity of solvents. Surface morphology of the nickel oxide film consisted of nanoparticles with uniform coverage of the substrate surface. The solvent of higher viscosity induced larger particle size. Band gap narrowing from 4.42 to 3.87 eV was observed using different solvents. The lower resistivity and Hall coefficient was obtained for prepared NiO films using higher polar solvents. The relationships between solvent physicochemical properties, preferred orientation, structural, optical and electrical properties of NiO films were investigated.

The anti-adherence and bactericidal activity of sol–gel derived nickel oxide nanostructure films: solvent effect

This study presents the characterization and antibacterial activity of nanostructure NiO films synthesized by sol–gel dip coating method using solvents of different polarities and viscosities without any catalysts, templates or surfactants. Methanol, 1,4-butanediol, ethanol, and 2-propanol were used as solvent. The antibacterial activity was tested against two common foodborne pathogenic bacteria Staphylococcus aureus (ATCC 25922) and Escherichia coli (ATCC 29213) using the so-called antibacterial drop test. X-ray diffraction, scanning electron microscopy, atomic force microscopy, UV–vis spectroscopy and static contact angles test were used to analysis the structure and morphology character, surface topography, optical property and surface wettability of different coatings, respectively. The characterization results showed different preferred crystallographic orientations, particle sizes, surface properties and optical band gap of NiO films according to the solvent physicochemical properties. The antibacterial efficiencies were affected by the physiological status of the bacterial cells and degree of bacteria adherence, morphologies and crystal growth habits, surface and optical properties of NiO samples.

Investigation of the effects of process variables on derived properties of spray dried solid-dispersions using polymer based response surface model and ensemble artificial neural network models

The objective of this study was to use different statistical tools to understand and optimize the spray drying process to prepare solid dispersions. In this study we investigated the relationship between input variables (inlet temperature, feed concentration, flow rate, solvent and atomization parameters) and quality attributes (yield, outlet temperature and mean particle size) of spray dried solid dispersions (SSDs) using response surface model and ensemble artificial neural network. The Box Behnken design was developed to investigate the effect of various input variables on quality attributes of final products. Moreover, Pearson correlation analysis, self organizing map, contour plots and response surface plot were used to illustrate the relationship between input variables and quality attributes. The influence of different physicochemical properties of solvent on the quality attributes of spray dried products was also investigated. Final validation of prepared models was done using binary SSDs of six model drugs with PVP. Results demonstrated the effectiveness of proposed PVP based model which can help scientists to gain detailed understanding of spray drying process of solid dispersion using minimal resources and time during early formulation development stage. It will also help them to ensure consistent quality of SSDs using broad range of input variables.

Apparent and intrinsic properties of commercial PDMS based membranes in pervaporative removal of acetone, butanol and ethanol from binary aqueous mixtures

The performance of three commercial poly(dimethylsiloxane) based membranes (Pervatech, Pervap 4060 and PolyAn) was studied in pervaporation of removal of acetone, butanol and ethanol from binary aqueous mixtures at 25°C. Physicochemical properties of solvents and PDMS were applied to describe affinities and interactions between transported mixture components and membrane. It was shown that high vapour pressure of acetone causes the most pronounced transport of this component through all investigated membranes.In terms of apparent properties, all membranes show high separation towards organic component of the binary mixture. Separation factors (βi/w) determined for aqueous mixture containing 0.01mol fraction of acetone are equal to 30, 62 and 39 for Pervatech, Pervap 4060 and PolyAn, respectively. Comparing these values to βBuOH/w values of water–butanol mixture (9, 31, 9 for Pervatech, Pervap 4060 and PolyAn, respectively), it seems that acetone is the most preferentially transported compound.In contrast, the intrinsic membrane properties discussed in terms of permeances and selectivities reveal that investigated membranes are selective towards butanol (intrinsic membrane selectivity αBuOH/w is equal to 3.6, 11.6 and 3.4 for Pervatech, Pervap 4060 and PolyAn, respectively). However, these membranes are nonselective or water selective (αi/w≤1) in contact with water–acetone and water–ethanol mixtures.

Determination of the interaction parameter χ in the Flory-Rehner equation for coal swelling processes

The correction factor χ of the Flory-Rehner equation, which takes into account the influence of the specific interaction of components on the degree of swelling, depends on the nature of a penetrant. It was found that the relationship between the value of χ and the physicochemical properties of solvents could be established by means of linear multiparameter equations. In the case of Rawhide coal, the cohesion energy density and the capability of penetrant for specific salvation are the determining factors.

Quantitative accounting for the medium effect at the catalytic decomposition of H2O2 in hydrophilic solvents

The experimental data on the effect of physicochemical properties of solvent on the rate of hydrogen peroxide decomposition catalyzed by cobalt ions were obtained using a method of adding inhibitors and were generalized quantitatively by the application of multiparametric linear equations.

Device Performance and Polymer Layer Morphology in Polymer Bistable Device (PBD): The Control of Physicochemical Properties of Solvent

The surface morphology control of poly(N-vinyl carbazole) (PVK) layer for the improvement of polymer bistable devices (PBDs) performance was investigated based on the simultaneous consideration of the compatibility of polymer with solvent and the polymer ordering behavior during the solvent evaporation by introducing the bisolvent system of chloroform and 1,1,2,2-tetrachloro-ethane (TCE). It was confirmed by ultra violet (UV)-vis spectroscopy that PVK has significantly higher compatibility with chloroform than TCE. On the other hand, atomic force microscope (AFM) revealed that the chloroform/TCE = 9/1 bisolvent led to the improved film morphology (the surface roughness of 0.190 nm) than chloroform, because the presence of TCE representing slower evaporation rate contributed to the enhancement of PVK ordering and arrangement during the solvent evaporation for the film formation. The great correlation was made between the film morphology properties and I-V characteristics of PBDs. The PBDs with PVK layer cast from the chloroform/TCE = 9/1 bisolvent showed dramatically improved bistability characteristics (Vth approximately equal to 2 V and Ion/Ioff ratio > 10(3)).

Hydrogen/deuterium exchange study of subtilisin Carlsberg during prolonged exposure to organic solvents.

It has been previously reported that prolonged exposure of an enzyme to organic solvents leads to substantial decrease of activity. This effect was found to be unrelated to the catalysts' structure or their possible aggregation in organic solvents, and up to the present day the cause for activity loss remains unclear. In the present work, the structural dynamics of the serine protease subtilisin Carlsberg (SC) have been investigated during prolonged exposure to two organic solvents by following hydrogen/deuterium (H/D) exchange of mobile protons. The enzyme, after lyophilization, was incubated in organic solvents at controlled deuteriated water activity for different times and the H/D exchange was allowed to take place. The amount of deuterium exchanged was evaluated by (2)H NMR, which in turn gave us a picture of the changing dynamics of our model enzyme during incubation and under different experimental conditions. Our results show that the flexibility of SC decreases during prolonged storage in 1,4-dioxane (Diox) and acetonitrile (ACN) as indicated by the observed 3- to 10-fold decrease in the apparent rate constants of exchange (k) of fast exchangeable protons (FEP) and slow exchangeable protons (SEP) in the protein. Our study also shows that SC is more flexible in ACN than in Diox (k 3-20 times higher in ACN for the FEP and SEP), suggesting that enzyme dynamics are affected by solvent physicochemical properties. Additionally, the enzyme dynamics are also affected by the method of preparation: decreased flexibility (k decreases 3- to 10-fold for FEP and SEP) is observed when the enzyme is chemically modified with poly ethylene glycol (PEGylated) or colyophilized with crown ethers. A possible relationship between activity, enantioselectivity (E), and structural dynamics is discussed, demonstrating that direct correlations, as have been attempted in the past, are hampered by the multi-variable nature and complexity of the system.

Urinary Mutagenicity in Chemical Laboratory Workers Exposed to Solvents

Solvents represent an important group of environmental pollutants to which people are exposed daily in the workplace. The physico chemical properties of solvents may result in disturbances to cellular structures, including damage to DNA. However, the effects of mixtures of solvents are not well known. Mutations caused by environmental agents are related to cancer development and other degenerative diseases. The work in a research laboratory that uses several types of solvents is equally predisposed to these hazards. In this study, we evaluated the mutagenicity of urine from 29 subjects exposed occupationally to solvents in a chemistry research laboratory and 29 subjects without occupational exposure (controls). Urine samples were collected in polyethylene containers at the end of the work shift. For the concentration and extraction of urine samples the XAD-2 resin was used with acetone as an eluting agent. Several strains of Salmonella typhimurium (TA100, TA98, TA97a, TA1535, YG1024) should be used to assess mutagenic susceptibilities among workers exposed to organic solvents. Different doses of extract (1.5; 3.0; 6.0 and 12.0 ml equivalents of urine per plate) were tested on S. typhimurium strains TA100 and YG1024, with and without metabolic activation. The mutagenic activity, measured in Salmonella typhimurium YG1024 with S9 mix, was significantly greater in urine from workers than from controls (p<or=0.05). These results indicate the relevance of using biomarkers to assess the risk of occupational exposure to organic solvents.