Mixture Of 2-propanol Research Articles

Measurement and modeling of transport properties of binary liquid mixtures containing oxygenates and n-alkanes

Dynamic viscosities (η) of the binary liquid mixtures of 2-propanol (1)+n-alkanes (C6, C7, C9) (2) at T=288.15 K to 303.15 K and ethanol (1)+n-alkanes (C6, C7, C8) (2) at T=308.15 K to 318.15 K were experimentally measured over the whole composition range. Experimental values of η were used to compute the deviation in dynamic viscosity (Δη) and these Δη values were correlated with the Redlich-Kister equation. The η values of binary mixtures were also calculated using several empirical correlations and mixing rules like Grunberg-Nissan, Tamura-Kurata, Kati-Chaudhari and McLaughlin-Ubbelohde and found that the Grunberg-Nissan correlation gave the best estimation. The Δη values were also predicted by an approach given by Singh et al. [Indian J Chem 29, 263 (1990)].

Effect of Temperature on the Cononsolvency of Poly(N-isopropylacrylamide) (PNIPAM) in Aqueous 1-Propanol

The wide range of applications of poly(N-isopropylacrylamide) (PNIPAM) is based on the temperature dependence of its coil-to-globule transition, which strongly relies on the solvent. Here, we focus on the cononsolvency effect of PNIPAM oligomers in aqueous 1-propanol mixtures that is studied by molecular dynamics simulations of single chains and membrane-like arrangements. The complete phase diagram is sketched from the radius of gyration of the simulated oligomers, and it is compared to that obtained from the hydrodynamic radius of PNIPAM microgels, finding a good agreement. At the water-rich region, the decrease of the lower critical solution temperature (LCST) with increasing cosolvent concentration is independent of the polymer length and concentration. In this region, the radius of gyration of our simulated oligomer is strongly temperature dependent and a coil–globule transition temperature is easily captured. Conversely, at the alcohol-rich region, simulations show a monotonically increasing radius of gyration of the oligomer with alcohol concentration, a radius that is practically independent of temperature. This finding is in line with a polymer phase separation, showing an upper critical solution temperature (UCST) for a small cosolvent concentration window, which depends on the polymer length and concentration. Hence, in this case, polymer–polymer effective interactions are key to phase separation instead of its single chain conformation, contrasting with the coil–globule transition. Indeed, we find a soft-coil like structure for the simulated oligomer around a propanol molar fraction of 0.24, which is close to the mixture composition where the UCST phase transition is detected. Finally, in line with an UCST scenario, our simulated membrane turns unstable at high temperature and alcohol concentration.

Investigation of the Microstructure and Rheology of Iridium Oxide Catalyst Inks for Low-Temperature Polymer-Electrolyte-Membrane Water Electrolyzers

Low-temperature polymer electrolyte membrane water electrolyzers (PEMWE) are an attractive clean energy technology to produce hydrogen (H2) as an energy carrier for several applications such as transportation and grid-scale energy storage and distribution (as supported by the US Department of Energy’s H2@Scale initiative). A critical component of PEMWE membrane electrode assemblies (MEA) is the catalyst layer (CL), where the electrochemical reactions occur. The microstructure of the CL plays a key role in MEA performance by affecting porosity, connectivity, etc. The CL microstructure is formed by the catalyst particles and an ionomer - which acts both as a binder for catalyst particles and as a proton conducting medium. The interactions between the ink components (catalyst-ionomer-solvent), and the ionomer concentration in the ink, which dictates the ink microstructure and the processing behavior during coating and drying, play a critical role in the formation of the CL microstructure. In this talk, an investigation of catalyst-ionomer interactions, microstructure and rheological behavior of the catalyst inks will be presented. The ink consists of iridium oxide (IrO2) catalyst particles and Nafion ionomer dispersed in a mixture of 1-propanol and water. A combination of rheology, ultra-small/small angle x-ray scattering, dynamic light scattering, and electrophoretic mobility were used to understand inter-particle and particle-ionomer interactions and characterize microstructure. Our results show that iridium catalyst dispersions in the absence of ionomer are agglomerated. When ionomer is added to the dispersion it adsorbs to the surface of IrO2 and provides stabilization through both electrostatic and steric mechanisms. As the ionomer content increases, we see increasing interparticle interactions. The stability and microstructure evolution as a function of ionomer concentration in the ink will be discussed. As well as their relation to device performance.

Ionomer Self-Assembly during Drying Process of Alcohol/Water Solutions Using Coarse-Grained Molecular Dynamics Simulations

The cathode catalyst layer (CL) is one of the principal components for proton exchange membrane fuel cells. CL is typically prepared by drying a catalyst ink consisting of Pt-C (platinum on a carbon powder support), ionomer, and solvents (water/alcohol mixtures). The structure and stability of ionomer aggregates in solutions are the key to the physical properties of PEMs, including water distribution, conductivity, and mechanical response of the membrane. Thus, understanding the ionomer aggregation behaviors in solutions is of great importance to gain a deep insight into fundamental morphological characteristics of ionomer membranes. The characterization of the ionomer aggregate structures in solutions has also been extensively explored in detail using experimental measurements. In this study, self-assembly of ionomers in a mixture of 1-propanol (NPA) and water have been investigated using coarse-grained molecular dynamics simulations. The dependence of NPA content on the ionomer structures was studied by systematically changing the NPA content in the system. The self-assembly behavior of ionomers into cylindrical bundle-like aggregates was observed and the aggregate size was found to be dependent on the NPA content in solutions. The effects of drying process on the ionomer aggregations will also be discussed in the presentation using the dimensionless Peclet number, which is used to describe the importance of evaporation to diffusion in a film of initial thickness. Figure 1

Understanding Polymer/Particle Interactions in Fuel-Cell Inks Using Model Systems

The formation process of hydrogen fuel-cell catalyst layers (CLs) is poorly understood, and represents a major area of effort with regard to increasing overall cell efficiency and durability. CLs are made from precursor inks that are dispersions of catalyst nanoparticles, ion-conducting polymer, and solvent (typically water and propanol mixtures). The polymer is generally a perfluorinated sulfonic-acid polymer, the prototypical example of which is Nafion. The duality between the strongly acidic sidechains and hydrophobic backbone of the polymer cause it to adopt unique conformations in solution, which are a strong function of the amount of water present in the ink.1 Indeed, tuning the ratio of water to propanol has recently been demonstrated to change the effective pH of these polymer solutions, possibly by changing the amount of exposed sidechains.2 The complex interplay between particle/solvent/polymer interactions govern CL ink and layer properties.3-4 However, much remains unknown about the fundamental forces controlling these interactions. In this study, we explore the polymer/particle interaction, and how it is affected by solvent quality. To do so, we use quartz crystal microbalance with dissipation (QCM-D) with model functionalized substrates that probe specific relevant forces (electrostatic, hydrophobic, etc.) in order to elucidate interactions present on the comparably more-complex carbon-platinum particle surface. Different ionomer dispersions in a variety of solvents are studied to understand ionomer adsorption and desorption behavior. QCM-D data is coupled with calorimetry measurements to extract thermodynamic binding information. Results reveal that hydrophobic interactions are a major driving force for ionomer adsorption. Acknowledgements This study was mainly funded under the Fuel Cell Performance and Durability Consortium (FC-PAD) funded by the Energy Efficiency and Renewable Energy, Fuel Cell Technologies Office, of the U.S. Department of Energy under contract number DE-AC02- 05CH11231. S.B. also acknowledges support from the National Science Foundation Graduate Research Fellowship under grant number DGE 1752814. References Welch, C.; Labouriau, A.; Hjelm, R.; Orler, B.; Johnston, C.; Kim, Y. S., ACS Macro. Lett. 2012, 1 (12), 1403-1407.Berlinger, S. A.; McCloskey, B. D.; Weber, A. Z., J. Phys. Chem. B. 2018, 122 (31), 7790-7796.Dixit, M. B.; Harkey, B. A.; Shen, F.; Hatzell, K. B., J. Electrochem. Soc. 2018, 165 (5), F264-F271.Hatzell, K. B.; Dixit, M. B.; Berlinger, S. A.; Weber, A. Z., J. Mater. Chem. A 2017, 5 (39), 20527-20533.

Temperature Dependent Solubility of Benzoic Acid in Aqueous Phase and Aqueous Mixtures of Aliphatic Alcohols

Abstract The benzoic acid solubility in aqueous phase and in various aqueous mixtures of methanol, ethanol and 2-propanol was determined at temperatures ranging from 303 to 333 K by an analytical technique. The results showed that the solubility of the acid in alcohols-water binary mixtures is high as compared to pure aqueous phase. The addition of alcohols to water favors the dissolution of benzoic acid which increases further with the increase in alcohols content of water within the investigated temperature range. The benzoic acid solubility in water alone and aqueous mixtures of the selected alcohols was in the order of; 2-propanol in water > ethanol in water > methanol in water > pure water. It is also observed that within the investigated temperature range, the acid solubility increases with rise in temperature in both the aqueous phase and alcohols-water binary solvents. The logarithm of the mole fraction of the acid’s solubility also showed a linear trend against the temperature. The experimental results obtained in the current study were compared with the reported literature for the studied acid and other organic acids in various solvents and showing a good agreement. The study will have implications in the processes involving separation, crystallization and pharmaceutical formulation in various industries.

Green pseudo-multicomponent synthesis of some new spirocyclopropane derivatives via electro-catalyzed reaction.

Due to the diverse applications of cyclopropane analogs in bioorganic, medicinal, and pharmaceutical chemistry, a clean and efficient procedure was established to synthesize spirocyclopropane via an electrochemical reaction which involves a sequence of Michael addition, halogenation, and intramolecular ring-closing reaction. In this study, an environmentally benign synthesis of spirocyclopropane was carried out through the condensation of indan-1,3-dione by aromatic aldehydes or 2-benzylidenemalononitrile derivatives. Constant current electrosynthesis was applied to a mixture of propanol containing sodium bromide as an electrolyte and a brominating agent at room temperature, respectively.

Electrooxidation of low-permittivity solvents in acetonitrile and solubility of trihexylamine in acetonitrile

In the first part of the work, anodic oxidation of some selected low-permittivity liquids (1,4-dioxane, diethyl ether, diisopropyl ether, dichloromethane, trichloromethane, tetrahydrofuran, carbon disulfide, triethylamine, trihexylamine, ethyl acetate, 1-pentyl acetate) was investigated on platinum electrode in acetonitrile which provided a higher-permittivity medium to enable the electrode processes. The pure solvents containing supporting electrolyte were also studied, and in several solvents, very low currents flowed when their cyclic voltammograms were recorded between 0 and 4 V. Contrarily, dissolving them in acetonitrile, high currents could be recorded and their anodic peaks appeared. The most remarkable difference between the pure liquid and acetonitrile solution was produced by the amines. Trihexylamine was immiscible with acetonitrile, so its solubility was determined by using the cosolvent calibration method (mixture of acetonitrile and 1-propanol) for the voltammetric determination, and the saturated concentration of the amine was 44.253 ± 0.564 mM.

Separation of the azeotropic mixture 2-propanol + water employing different imidazolium ionic liquids as solvents

The liquid-liquid equilibria of the ternary systems water (1) + 2-propanol (2) + [emim][Tf2N] (3) and water (1) + 2-propanol (2) + [hmim][Tf2N] (3) at 283.2, 303.2 and 323.2 K and atmospheric pressure were investigated, in order to achieve a better knowledge of the ternary mixture behaviour. The capability of [emim][Tf2N] and [hmim][Tf2N] as solvents in the separation of the azeotropic mixture water + 2-propanol was studied through the distribution coefficient and selectivity, and compared with the results obtained with other ionic liquids in the same azeotropic mixture studied before by our research group. The thermodynamic parameters of both ternary mixtures were calculated by the non-random two-liquid (NRTL) and universal quasichemical (UNIQUAC) models.

Liquid Densities and Speed of Sound for Ionic Liquid (2-HEAA and 2-HDEAA) + Alcohol (1-Propanol and 2-Propanol) Mixtures at T = (293.15–323.15 K) and Atmospheric Pressure

Liquid–liquid equilibrium data are widely used in many industrial sectors. For this reason, it is important to know thermodynamics binary mixture data to better understand molecular interactions between components. This work reports experimental density (ρ) and speed of sound (υ) data for 2-hydroxyethanolamine acetate + 1-propanol, 2-hydroxyethanolamine acetate + 2-propanol, 2-hydroxydiethanolamine acetate + 1-propanol, and 2-hydroxydiethanolamine acetate + 2-propanol binary mixtures, over a wide composition range, between 293.15 and 323.15 K, and at atmospheric pressure (101.3 kPa). For this purpose, a vibrating tube densitometer was used to perform density and speed of sound experimental measurements. From these data, important derivative properties have been calculated, such as isentropic compressibility (κs), apparent molar isentropic compressibility (κø), excess molar volumes (VmE), and apparent molar volume (VØ).

Liquid-Liquid-Solid Equillibrium of Water + 2-propanol + Kosmotropic Salts: Construction of Phase Diagrams and Understanding of Salting-out Effects Using Volumetric and Compressibility Studies

Background: Triangular phase diagrams are important to understand the phase behaviors in ternary systems. The salting out of alcohol from water by kosmotropic salt has long been known, but the molecular interactions and the mechanism of bond breaking and making processes has not yet been fully understood. Objective: To understand the salting-out of 2-propanol from water using kosmotropic salts (Na2S2O3, Na2SO4 and Na2SO3). To study the phase equilibria of liquid-liquid, liquid-solid and liquid-liquid-solid system by constructing ternary phase diagrams. To determine the solute-solute, solute-solvent, and solvent-solvent molecular interactions to resolve the salting- out effect. Methods: The solubility data of Na2S2O3/Na2SO4/Na2SO3 salts have been reported in pure water, 2-propanol and water + 2-propanol mixtures in different concentrations at 298.15 ± 1 K. The ternary phase diagrams have been constructed from the obtained solubility data. The volumetric and acoustic data of binary and ternary systems of water + 2-propanol, water + salt and water + 2-propanol + salt has been determined using density meter and interferometer. Results: The ternary phase diagrams have been constructed for water+2-propanol+ Na2S2O3/Na2SO4/Na2SO3 system. The rise in sound velocity signifies more structural interactions in binary water-alcohol and water-salt systems, while the relation is rather change with the ternary system, as the water-alcohol sheath will be broken by the kosmotropic salt which results in to salt-water sheath. Conclusion: The density, sound velocity and adiabatic compressibility results suggest that phase separation phenomenon is due to the bond breaking and bond making process along with hydrophobic hydration and hydrophobic interactions. The anion S2O32-, SO42- and SO3 2- promote salting-out effect and the strength of these effects decreases in the order S2O32->SO42->SO32-.

Applying hybrid genetic–PSO technique for tuning an adaptive PID controller used in a chemical process

The conventional PID controller has static parameters that cannot be changed at different operating conditions. As a result, the term ‘adaptive PID controller’ has appeared to solve this problem. This controller can be tuned using intelligent techniques such as Fuzzy Logic Control, Neural Network Control, or Adaptive Neuro-Fuzzy Inference Systems. However, the choice of the suitable parameters for these intelligent controllers has a direct effect on their performance. Metaheuristics algorithms—with their powerful performance, speed, and optimal parameter selection—can be applied for choosing controller parameters efficiently. In this paper, a hybrid of genetic algorithm and particle swarm optimization is proposed to tune the parameters of different adaptive PID controllers. To evaluate the performance of the proposed hybrid optimization method on the different adaptive PID controllers, these controllers are applied to control the operation of one of the most difficult chemical processes, the divided wall distillation column. The proposed column used in this work separates a ternary mixture of ethanol, propanol, and n-butanol. Our proposed hybrid optimization technique is compared with the genetic algorithm, and simulation results show that our proposed hybrid genetic-particle swarm technique outperforms genetic algorithm for different disturbances.

Cylindrical Micelles by the Self-Assembly of Crystalline-b-Coil Polyphosphazene-b-P2VP Block Copolymers. Stabilization of Gold Nanoparticles.

During the last number of years a variety of crystallization-driven self-assembly (CDSA) processes based on semicrystalline block copolymers have been developed to prepare a number of different nanomorphologies in solution (micelles). We herein present a convenient synthetic methodology combining: (i) The anionic polymerization of 2-vinylpyridine initiated by organolithium functionalized phosphane initiators; (ii) the cationic polymerization of iminophosphoranes initiated by –PR2Cl2; and (iii) a macromolecular nucleophilic substitution step, to prepare the novel block copolymers poly(bistrifluoroethoxy phosphazene)-b-poly(2-vinylpyridine) (PTFEP-b-P2VP), having semicrystalline PTFEP core forming blocks. The self-assembly of these materials in mixtures of THF (tetrahydrofuran) and 2-propanol (selective solvent to P2VP), lead to a variety of cylindrical micelles of different lengths depending on the amount of 2-propanol added. We demonstrated that the crystallization of the PTFEP at the core of the micelles is the main factor controlling the self-assembly processes. The presence of pyridinyl moieties at the corona of the micelles was exploited to stabilize gold nanoparticles (AuNPs).

Liquid–Vapor Phase Transitions and Critical Properties of the C3H7OH–C6H14 System

Proceeding from the experimental (p,T,x) and (p,ρ,T,x) dependences for mixtures of 1-propanol and n-hexane (mole fractions 0.2, 0.5, 0.8, and 0.9) in the two-phase (liquid–vapor), single-phase (liquid and vapor), near-critical, and supercritical regions, the parameters of the points of liquid–vapor phase transformations have been determined by the method of isochore kinks p = f(T)ρ,x and the parameters of the critical points have been found by the semigraphical method with allowance for the scaling behavior. The dependences of the pressure on temperature, density, and composition along the phase-coexistence curve are described by a three-parameter polynomial equation of state: expansion of the compressibility factor Z = p/RTρ in powers of the reduced density, reduced temperature, and composition. The mean relative error of deviation of the calculated pressures from experimental values does not exceed 1%. The temperature dependence of the system density along the liquid–vapor phase-coexistence curve is described by two power-law functions at critical exponent β0 = 0.338 ± 0.002: far from the critical point and in the symmetric part of the equilibrium curve. The mean relative error is 1.47%.

Novel non-aqueous MEA solutions for CO2 capture

Present obstacles for CO2 capture involve reducing capital and energy costs. This study describes carbon dioxide capture with monoethanolamine (MEA) in organic solvents as a way to reduce the energy consumption during desorption. The solvents used in this study are a mixture of ethylene glycol and 1-propanol (EG/PrOH), diethylene glycol monoethyl ether (DEGMEE), and N-methylformamide (NMF). A microwave regeneration technique was used to easily and quickly screen the performances of the amine solutions and experiments were designed to investigate the solvent effects on CO2 capture by MEA. Globally, DEGMEE solutions resulted in the lowest energy consumptions and good CO2 cyclic capacities; the best solutions reducing the energy consumption by 78% in comparison to the traditional 30 wt% MEA aqueous solution. These findings show that organic solvents have much promise in improving CO2 capture technology. It was also found that using NMF greatly enhanced the CO2 absorption kinetics but was detrimental during the desorption step.

Controlled polarity of CO2 switchable solution with DBU and alcohols

Solvent polarity switched by CO2 of 1,8-Diazabicyclo [5.4.0] undec-7-ene (DBU) + alcohol mixture was investigated on the effect of alcohol species and DBU mole fraction. The alcohols used in this work were ethylene glycol, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol and 1-octanol. Kamlet – Taft parameter was applied for the evaluation of the solvent polarity of DBU + alcohol mixture treated by CO2. Ultraviolet–visible spectra of a solvatochromic dye N, N-Dimethyl-4-nitroaniline was used for the determination of the Kamlet – Taft parameter. The DBU mixture with ethylene glycol provides the switchable polarity by CO2 larger than those with other alcohol. The switchable polarity of DBU + ethylene glycol and DBU + 1-propanol mixtures increases with the mole fraction of DBU. A molecular information from quantum calculation can provide the modeling of the switchable polarity by CO2. The Kamlet – Taft parameter of DBU + alcohol mixture is estimated from the molecular surface charge density. The estimated Kamlet – Taft parameter of DBU + alcohol mixture represents the experimental data within the absolute deviation 0.1.

Salts Effect on Isobaric Vapor–Liquid Equilibrium for the Azeotropic Mixture 2-Propanol + Water

Vapor–liquid equilibrium (VLE) data for the systems 2-propanol + water + calcium chloride, 2-propanol + water + magnesium chloride, 2-propanol + water + calcium nitrate, and 2-propanol + water + magnesium nitrate were measured at the pressure of 101.3 kPa. Experimental data of all ternary systems passed the thermodynamic consistency test by modified McDermott–Ellis method. Then, the effects of salts on the vapor phase mole fraction of 2-propanol and the relative volatility of 2-propanol to water were analyzed. Results show that the azeotropic point of the system 2-propanol and water can be removed with addition of the salts, and the salting-out effects follow the order calcium nitrate > calcium chloride > magnesium nitrate > magnesium chloride. Furthermore, the LIQUAC model was adopted to correlate the VLE experimental data of the systems. The comparative results of the average relative deviation (Δz̅) and the corresponding standard deviations (σ) between the experimental and calculated values indicate that LIQUAC model is suitable for the VLE calculation for the systems of 2-propanol + water + salts.

Solubility Measurements and the Dissolution Behavior of Malonic Acid in Binary Solvent Mixtures of (2-Propanol + Ethyl Acetate) by IKBI Calculations

The equilibrium solubilities of malonic acid in 2-propanol and ethyl acetate mono solvents, as well as in (2-propanol + ethyl acetate) binary solvent mixtures, were determined from 278.15 to 313.15 K. The obtained solubility data were correlated using thermodynamic models including the modified Apelblat equation, λh equation, NRTL model, GSM model and the modified Jouyban–Acree model. The dissolution mechanism of malonic acid in (2-propanol + ethyl acetate) solvent mixtures was interpreted theoretically. The inverse Kirkwood–Buff integrals method was applied and it was found that the value of δx1,3 is negative in high ethyl acetate fractions, but becomes positive at 2-propanol mole fractions greater than 0.60 at 298.15 K. In addition, molecular dynamic simulations were carried out to characterize the intermolecular interactions using the radial distribution function.

Use of spent coffee ground biochar as ambient PAHs sorbent and novel extraction method for GC-MS analysis.

In recent years, biochar has received a significant amount of attention for its potential beneficial applications in various fields due to its bio-physico-chemical properties. The spent coffee ground biochar was prepared by slow pyrolysis for adsorption of 16-polycyclic aromatic hydrocarbons (PAHs) in ambient air. New materials and extraction methods were developed for PAHs analysis, particularly for low molecular weight (2-4 rings) PAHs, which are likely to evaporate at room temperature. Production and characterization of biochar and its extraction parameters after PAHs adsorption were investigated and optimized. The biochar production at 500°C provided adequate quality for PAHs adsorption with a 35% yield. An effective clean-up method for biochar was proposed. A new method of PAHs extraction from biochar was developed using 25mL of a mixture of dichloromethane and 2-propanol (4:1) for 30min at low temperatures (5-10°C). A test on the efficiency of the extraction method was carried out and recoveries of 85-104% of PAHs were obtained. The lab-made biochar was also tested for its potential in ambient PAHs sampling and compared with a commercial sorbent (XAD-2). The results revealed that almost the same concentrations of ambient PAHs (ng/m3) were absorbed by both sorbent types, particularly with regard to the 4 ring-PAHs.

Isomeric and structural effects in polymer cononsolvent systems

Thermoresponsive poly (N-isopropylacrylamide) (PNIPAM) has many analogs that exhibit cononsolvency behavior in mixtures of water and an alcohol. Cononsolvency is characterized by a combination of good solvents for a polymer that results in decreased solubility. In this work, the cononsolvency behavior of linear PNIPAM, four-arm (4f) star PNIPAM, and linear poly(N-n-propylacrylamide) (PNnPAM), with terminal groups that vary in hydrophobicity, were investigated in mixtures of water and propanol. Polymers were synthesized by RAFT polymerization and subsequently functionalized with one pot aminolysis/thiol-ene chemistry. Turbidimetry measurements and dynamic light scattering (DLS) were used to study the cononsolvency behavior by determining the critical solution temperature (Tc). The measurements show that the size and shape of the hydrophobic region of both the solvent and n-alkyl acrylamide monomer affect Tc and the phase transition behavior. The findings suggest methods to impart multiresponsiveness to soft material systems.