Showing papers in "Journal of Chemical & Engineering Data in 2013"

Removal of a Cationic Dye from Aqueous Solution Using Graphene Oxide Nanosheets: Investigation of Adsorption Parameters

Abstract: In this study, graphene oxide (GO) nanosheets have been used for the adsorption of methyl green, a cationic dye from aqueous solution. GO nanosheets consist of single layered graphite structure decorated with a number of oxygen containing functionalities such as carboxyl, epoxy, ketone, and hydroxyl groups which impart a negative charge density to it in aqueous solution at a wide range of pH. Thus, GO nanosheets can be predicted as a good adsorbent material for the adsorption of cationic species. The adsorption of the methyl green onto the GO nanosheets has been carried out at different experimental conditions such as adsorption kinetics, concentration of adsorbate, pH, and temperature. The kinetics of the adsorption data were analyzed using four kinetic models such as the pseudofirst-order model, pseudosecond-order model, intraparticle diffusion, and the Boyd model to understand the adsorption behavior of methyl green onto the GO nanosheets and the mechanism of adsorption. The kinetics of adsorption resu...

Improvement of Quality in Publication of Experimental Thermophysical Property Data: Challenges, Assessment Tools, Global Implementation, and Online Support

Abstract: This article describes a 10-year cooperative effort between the U.S. National Institute of Standards and Technology (NIST) and five major journals in the field of thermophysical and thermochemical properties to improve the quality of published reports of experimental data. The journals are Journal of Chemical and Engineering Data, The Journal of Chemical Thermodynamics, Fluid Phase Equilibria, Thermochimica Acta, and International Journal of Thermophysics. The history of this unique cooperation is outlined, together with an overview of software tools and procedures that have been developed and implemented to aid authors, editors, and reviewers at all stages of the publication process, including experiment

Synthesis and Thermophysical Properties of Biocompatible Cholinium-Based Amino Acid Ionic Liquids

Abstract: Nowadays the knowledge of thermodynamic properties for amino acid ionic liquids (AAILs) has been paramount for the design of many chemical processes. In this present work, a series of cholinium-based AAILs ([Ch][AA]) were synthesized by neutralization of choline hydroxide solution with five amino acids and then were characterized by 1H NMR, Fourier transform infrared (FT-IR), elemental analysis, thermogravimetry, and differential scanning calorimetry (DSC) analysis. Physico-chemical properties such as density, viscosity, refractive index, and conductivity were measured and correlated with the empirical equations in a wide temperature range. The thermal expansion coefficient values were also calculated from the acquired experimental density values. From the experimental data, it was found that the density, viscosity, and refractive index decreased while conductivity increased with the increase of temperature. The correlation results were proposed to be in good agreement with the experimental data, and opti...

Kinetics and Adsorption Behavior of the Methyl Blue at the Graphene Oxide/Reduced Graphene Oxide Nanosheet–Water Interface: A Comparative Study

Abstract: The adsorption behavior of the methyl blue dye molecule, a mutagenic agent onto the graphene oxide (GO) and reduced graphene oxide (rGO) nanosheets, has been investigated at different pH values, adsorption times, temperatures, and also in the presence of different ions like Na+, Ca2+, Mg2+, and SO42–. A green solution chemistry approach has been adopted for the synthesis of rGO where ascorbic acid is used as a reducing agent under ultrasonication. A kinetic investigation has revealed that adsorption of methyl blue at the GO/rGO nanosheets–water interface follows linear pseudo second-order kinetics. The endothermic and spontaneous nature of the adsorption process was ascertained by the thermodynamic parameters such as Gibbs free energy change (ΔG°), enthalpy change (ΔH°), and entropy changes (ΔS°). The adsorption density of methyl blue at the GO nanosheet–water interface increases with increasing pH of the medium, while it decreases at the rGO nanosheet–water interface. Such results indicates that methyl b...

Adsorption of Au(III), Pd(II), and Pt(IV) from Aqueous Solution onto Graphene Oxide

Abstract: Graphene oxide (GO) was prepared and characterized by Fourier transform infrared spectrometry (FT-IR) and scanning electron micrographs (SEM). Batch adsorption studies were carried out to investigate the adsorption data, including the effects of pH, initial concentration, contact time, and temperature. The adsorption of Au(III), Pd(II), and Pt(IV) was optimum at pH 6.0. The adsorption isotherms all obeyed the Langmuir equation in the case of Au(III), Pd(II), and Pt(IV), and the maximum adsorption capacities were 108.342 mg·g–1, 80.775 mg·g–1, and 71.378 mg·g–1, respectively. The adsorption kinetics of Au(III), Pd(II), and Pt(IV) onto GO followed a pseudosecond-order kinetic model, indicating that the chemical adsorption was the rate-limiting step. Thermodynamic parameters such as Gibbs energy (ΔGo), enthalpy (ΔHo), and entropy (ΔSo) were calculated, indicating that the adsorption were spontaneous, endothermic, and feasible. The desorption studies showed that the best desorption reagents were 0.5 mol·dm–3 ...

Formation of Deep Eutectic Solvents by Phenols and Choline Chloride and Their Physical Properties

Abstract: Novel deep eutectic solvents (DES) based on three different hydrogen-bond donors (HBD), namely phenol, o-cresol, and 2,3-xylenol, and choline chloride (ChCl) were successfully synthesized with different mole ratios of HBD to ChCl. Melting temperature of these DES were measured. Compared with an ideal mixture of the two components, the freezing temperature of the DES depresses greatly from (120 to 127) K. The physical properties, such as density, viscosity, and conductivity of phenol-based and o-cresol-based DES were determined at atmospheric pressure and temperatures from (293.2 to 318.2) K at an interval of 5 K. The results show that the type of HBD, the mole ratio of HBD to ChCl, and temperature have great influences on the physical properties of DES. Densities and viscosities of DES formed by phenol and ChCl decrease with increases of temperature and phenol content. The conductivities of the DES are from (1.40 to 7.06) mS·cm–1, similar to that of room temperature ionic liquids. The conductivities of th...

Thermal Properties of Cyano-Based Ionic Liquids

Abstract: Nowadays, extraction of aromatics from aromatic/aliphatic mixtures is being investigated using cyano-based ionic liquids (ILs) as a new green alternative to currently used conventional organic extraction solvents, such as sulfolane. In this process, the maximum operation temperature (MOT) of the IL is a decisive property to know. Thus, thermal behavior of ILs is a target issue to study. The MOTs of cyano-based ILs 1-ethyl-3-methylimidazolium dicyanamide ([emim][DCA]), 1-butyl-3-methylimidazolium dicyanamide ([bmim][DCA]), 1-ethyl-3-methylimidazolium thiocyanate ([emim][SCN]), 1-butyl-3-methylimidazolium thiocyanate ([bmim][SCN]), and 1-ethyl-3-methylimidazolium tricyanomethanide ([emim][TCM]) have been determined using dynamic and isothermal thermogravimetric analyses. In addition, specific heats from (296.2 to 372.2) K of all ILs included in this work have been also measured using differential scanning calorimetry (DSC). The MOT for [emim][TCM] was the highest, whereas the MOT for [emim][DCA], [bmim][DCA...

Adsorption of Cationic Dyes on a Cellulose-Based Multicarboxyl Adsorbent

Abstract: A novel adsorbent based on cellulose (CGD) was prepared via modifying with glycidyl methacrylate (GMA) and diethylenetriamine pentaacetic acid (DTPA), characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and differential thermogravimetry (DTA/TGA). Malachite green (MG) and basic fuchsine (BF) were used to resemble cationic dyes in wastewaters. The influences of several parameters (contact time, pH, temperature, initial concentration) were evaluated to determine the best adsorption conditions. Langmuir adsorption isotherm items explained MG adsorption well, while BF was fitted well with the Freundlich model. The maximum adsorption capacities were greater than some other reports, 1155.76 mg·g–1 for a BF internal concentration of 2000 mg·L–1 and 458.72 mg·g–1 for MG in theory. Kinetics and thermodynamics were adopted to explain in-depth information associated with the adsorption process. The adsorption processes of dyes were both feasib...

Temperature and Composition Effect on CO2 Miscibility by Interfacial Tension Measurement

Abstract: Crude oil reservoirs have different temperatures, compositions, and pressures, therefore oil recovery performance by CO2 injection varies from one case to another. Furthermore, it is predicted that lower interfacial tension between injected CO2 and reservoir fluid results in more oil recovery. In this study, we investigate the effect of temperature on the equilibrium interfacial tension between CO2 and three different oil fluids at different pressures. Also minimum miscible pressure (MMP) is measured by the vanishing interfacial tension (VIT) technique to determine the temperature effect on the CO2 miscible gas injection. The results on different pure and mixtures of hydrocarbon fluids show that for pressures up to 5.2 MPa, the higher the temperature was, the lower was the interfacial tension (IFT) measured. However, for the cases with pressure higher than 5.2 MPa, as the temperature was increased, the IFT increased too. In addition the VIT technique is used to measure the MMP of CO2 and pure paraffin; th...

Removal of Methylene Blue from Aqueous Solutions by Sewage Sludge Based Granular Activated Carbon: Adsorption Equilibrium, Kinetics, and Thermodynamics

Abstract: Sewage sludge based granular activated carbon (SSGAC) was prepared using calcium sulfate as binder. The porous structure and surface chemical properties of SSGAC were characterized by N2 adsorption isotherm, FTIR, PZC, and Boehm titration. The results showed that the SSGAC was a typical mesoporous adsorbent of which the percentages of mesoporous surface area and volume are 72.81 % and 88.89 %, and the acid groups were dominant on its surface. The adsorption mechanism of MB adsorption onto SSGAC was also investigated by different adsorption models. The results showed that the maximum MB adsorption amount could be 131.8 mg g–1, and the MB adsorption onto SSGAC was a heterogeneous, spontaneous, and endothermic process while physisorption was dominant. The MB adsorption process was well described by the pseudosecond-order kinetic mode, and the MB diffusion in micropores was the potential rate-controlling step.

Physicochemical Studies on the Micellization of Cationic, Anionic, and Nonionic Surfactants in Water–Polar Organic Solvent Mixtures

Abstract: The effect of cosolvent (ethane-1,2-diol and dimethyl sulfoxide) on the self-assembly of three surfactants, N,N,N-trimethyl-1-dodecanaminium bromide (DTAB), sodium [dodecanoyl(methyl)amino]acetate (SDDS), and polyoxyethylene (20) sorbitan monolaurate (Tween-20) in aqueous solution have been investigated by conductometric, tensiometric, and viscometric techniques at 298 K. The main focus was on the effect of solvent on critical micelle concentration (cmc), free energy contribution to micellization (ΔGm0), tail transfer Gibbs free energy (ΔGtrans0), Gibbs adsorption energy (ΔGads0), and some micellar interfacial parameters, for example, Gibbs surface excess (Γmax), minimum area per surfactant molecule (Amin), surface pressure (Πcmc), and pC20(= −log(C20), where C20 is the surfactant molar concentration required to reduce the surface tension of mixed solvent by 20 mN m–1). With increasing concentration of cosolvent in the binary mixture, the cohesive force decreases, and surfactant molecules are more soluble...

Solubility of CO2 in Aqueous Solutions of CaCl2 or MgCl2 and in a Synthetic Formation Brine at Temperatures up to 423 K and Pressures up to 40 MPa

Abstract: We report the solubility of carbon dioxide in CaCl2(aq) and MgCl2(aq) at molalities of (1, 3, and 5) mol·kg–1, temperatures of (308 to 424) K and pressures up to 40 MPa. We also report the solubility of CO2 in a synthetic formation brine containing 0.910 mol·kg–1 NaCl and 0.143 mol·kg–1 KCl over the same ranges of temperature and pressure. The expanded uncertainties at 95 % confidence are 0.03 K in temperature, between (0.08 and 0.15) MPa in bubble pressure and 0.00015 in the mole fraction of CO2 in the solution at its bubble point. The results show a strong salting-out effect, whereby the solubility declines with increasing molality of salt, which is some (20 to 30) % greater in CaCl2(aq) or MgCl2(aq) than in the synthetic formation brine at the same molality.

Molecular Simulation Studies on the Vapor–Liquid Phase Equilibria of Binary Mixtures of R-1234yf and R-1234ze(E) with R-32 and CO2

Abstract: Different fluoropropenes are currently considered as refrigerants, either as pure compounds or as components in low GWP (global warming potential) refrigerant mixtures. However, experimental data for the thermophysical properties of fluoropropenes and their mixtures are in general rare, which hampers the exploration of their performance in technical applications. In our earlier work [Raabe, G.; Maginn, E. J. J. Phys. Chem. B2010, 114, 10133–10142; Raabe, G. J. Phys. Chem. B2012, 116, 5744–5751], we introduced a transferable force field for fluoropropenes that enables reliable predictions of the properties of different fluoropropenes. In this work, we apply the force field model for fluoropropenes to molecular simulation studies on the vapor–liquid phase equilibria in binary mixtures of the tetrafluoropropenes R-1234yf or R-1234ze(E) with the difluoromethane R-32 and CO2 at temperatures from T = (273.15 to 313.15) K. Additionally, we present correlations of the VLE by the PC-SAFT equation of state.

Volumetric and Transport Properties of Binary Mixtures of n-Octane + Ethanol, + 1-Propanol, + 1-Butanol, and + 1-Pentanol from (293.15 to 323.15) K at Atmospheric Pressure

Abstract: We present densities and dynamic viscosities of binary mixtures of n-octane with ethanol, 1-propanol, 1-butanol, and 1-pentanol. Measurements are performed at atmospheric pressure from (293.15 to 3...

Adsorption/Desorption of Organic Acids onto Different Adsorbents for Their Recovery from Fermentation Broths

Abstract: Activated carbon and a weak base resin were used as adsorbents for organic acids of relevance in green chemistry. Equilibrium adsorption studies in single and binary systems of acetic, propionic and butyric acids were carried out using various solvents (water, ethanol, and n-propanol) and equilibrium isotherm models were tested. The resin had a higher adsorption capacity than the activated carbon (about 35 %). Data on adsorption of binary systems suggested competition between the acids and a chain size dependence. In the studies using organic solvents, the resin showed a higher adsorption capacity than the activated carbons. This work showed the importance of conducting a complete and integrated study of an adsorption process including both adsorption and desorption steps. The use of resin with n-propanol as eluent achieved the best recovery in the simulated purification of propionic acid.

High-Pressure Physicochemical Properties of Ethyl Caprylate and Ethyl Caprate

Abstract: The components of biodiesel derived from coconut oil or babassu oil such as ethyl caprylate and ethyl caprate are studied. The experimental speeds of sound in ethyl caprylate were reported at p = (0.1 to 101.32) MPa and at T = (292.90 to 318.32) K and in ethyl caprate at p = (0.1 to 101.32) MPa and at T = (292.90 to 318.28) K together with the experimental densities at 0.1 MPa for ethyl caprylate at T = (278.15 to 358.15) K and for ethyl caprate at T = (283.15 to 353.14) K as well as heat capacities were reported at 0.1 MPa for ethyl caprylate at T = (285.01 to 343.78) K and for ethyl caprate at T = (286.16 to 341.11) K. The density, adiabatic and isothermal compressibilities, heat capacity, isobaric thermal expansion, and internal pressure at elevated pressures and temperatures were calculated from the experimental results in the way described by Davis and Gordon (J. Chem. Phys.1967, 46, 2650–2660) with the aim of studying the effect of changing of the carbon chain length from ethyl caprylate to ethyl ca...

Activity Coefficients at Infinite Dilution for Organic Solutes Dissolved in Three 1-Alkyl-1-methylpyrrolidinium Bis(trifluoromethylsulfonyl)imide Ionic Liquids Bearing Short Linear Alkyl Side Chains of Three to Five Carbons

Abstract: In this work, we report the infinite dilution activity coefficients (γ1,2∞) of 39 to 43 diverse organic solutes dissolved in three 1-alkyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ionic liquids (IL) homologues bearing propyl, butyl, and pentyl n-alkyl side chains, respectively, as determined by inverse gas chromatography at temperatures from 323 K to 343 K. The organic solutes include various (cyclo)alkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, thiophene, ethers, nitroalkanes, and ketones. The measured retention data were further transformed to gas-to-IL and water-to-IL partition coefficients using established thermodynamic approaches based upon the corresponding gas-to-water partition coefficients of the test solutes. Both sets of partition coefficients were interpreted with a modified form of the basic Abraham general solvation parameter model. The mathematical correlations obtained by regression analysis back-calculated the observed gas-to-IL and water-to-IL partition coeff...

Effect of 1-Ethyl-3-methylimidazolium Bromide Ionic Liquid on the Volumetric Behavior of Some Aqueous l-Amino Acids Solutions

Abstract: Densities of aqueous solutions of glycine, l-alanine, l-arginine, and l-phenylalanine containing 1-ethyl-3-methylimidazolium bromide, [EMIm]Br, have been determined at T = (298.15 and 308.15) K. From the experimental density data, the apparent molar volumes (VΦ) and the standard partial molar volumes (VΦ0) at (298.15 and 308.15) K have been calculated. The values of standard partial molar volumes of transfer (ΔtrVΦ0) are also obtained and are negative for glycine, l-alanine, and l-phenylalanine while positive for l-arginine. The ΔtrVΦ0 values all increased with the increase of the temperature and also the [EMIm]Br content. The obtained volumetric parameters will be helpful to understand mixing effects and other complex biological processes between head and side chain groups of amino acids and ionic liquid [EMIm]Br in aqueous solution.

Solubility of Carbon Dioxide in Aqueous Solutions of Monoethanolamine in the Low and High Gas Loading Regions

Abstract: Reliable data for the solubility of carbon dioxide in aqueous solutions of monoethanolamine are required for the design and evaluation of postcombustion carbon capture processes. As published experimental data for the solubility of carbon dioxide in aqueous solutions of monoethanolamine show considerable scatter, the solubility of carbon dioxide in aqueous solutions containing (15 and 30) mass percent of monoethanolamine; that is, (2.9 and 7.0) mol·(kg H2O)−1 respectively, was measured at molar ratios of carbon dioxide to monoethanolamine in the liquid solution from 0.1 to 1.3 at (313, 353 and 393) K. An apparatus based on headspace gas chromatography (on the synthetic gas solubility method) was used for the experiments at low (high) gas loadings, that is, at partial pressures of carbon dioxide from (1 to 80) kPa (from (0.4 to 8.6) MPa). The new experimental results are compared to literature data and used to parametrize a physicochemical thermodynamic model based on the extended Pitzer equation for the G...

Thermal Conductivity of [C4mim][(CF3SO2)2N] and [C2mim][EtSO4] and Their IoNanofluids with Carbon Nanotubes: Experiment and Theory

Abstract: Measurements of the thermal conductivity of ionic liquids are extremely important for current chemical plant design of new environmentally safe processes. Existing data are very scarce and inaccurate. IoNanofluids have emerged as a possible alternative to current engineering fluids for heat transfer applications, namely in small volume heat exchangers. In the present paper we report new data on the thermal conductivity of of 1-n-butyl-3-methylimidazolium bis(trifluoromethanesulfonylimide ([C4mim][(CF3SO2)2N]) and 1-ethyl-3-methylimidazolium ethylsulfate ([C2mim][EtSO4]) at temperatures between (293 and 343) K and IoNanofluids with multiwalled carbon nanotubes based on them, to understand the effect of adding nanomaterials to a ionic liquid matrix and its effect on the mentioned thermal property. The application of existing models to predict the behavior of the IoNanofluids, namely, the enhancement in the thermal conductivity, showed that it is fundamental to understand better the mechanism of heat transfe...

Speed of Sound, Density, and Derivative Properties of Ethyl Myristate, Methyl Myristate, and Methyl Palmitate under High Pressure

Abstract: Speeds of sound have been measured in ethyl myristate (C16H32O2), methyl myristate (C15H30O2), and methyl palmitate (C17H34O2) at pressures up to 100 MPa along isotherms ranging from (293.15 to 403.15) K. The measurements were carried out using a pulse echo technique operating at 3 MHz. Additional compressed liquid density measurements were performed from (293.15 to 393.15) K with pressures from (0.1 to 100) MPa in order to evaluate isentropic compressibility using speed of sound measurements. An equation of state that represents both the density and the speed of sound temperature reported experimental data within their estimated uncertainties is given to evaluate the volume as well as its derivatives of these components.

Adsorption Equilibria of Cu2+, Zn2+, and Cd2+ on EDTA-Functionalized Silica Spheres

Abstract: Ethylenediaminetetraacetic acid (EDTA) functionalized silica spheres were used to remove metal ions from aqueous solutions. The adsorption kinetics of Cu2+, Zn2+, and Cd2+ (60 mg·L–1, pH 5.5) were fitted to the pseudosecond order model. Adsorption equilibria were reached within 20 min, indicating that chemisorption may be the limiting step in the adsorption process. Adsorption isotherms were analyzed with nonlinear models by considering the ERRSQ error function and the determination coefficient R2. The data with monoion solutions (10 mg·L–1 to 300 mg·L–1) were tested with Langmuir, Freundlich, and Redlich–Peterson isotherm models. The best fit was found with the Langmuir model, and maximum adsorption capacities followed the order: Cu2+ > Zn2+ > Cd2+. Breakthrough curves were obtained using filled columns. The adsorbed ions were quantitatively recovered on elution with hydrogen chloride (0.10 M). After three adsorption–recovery cycles, the metal ions could still be recovered almost quantitatively, which de...

Universal Method for Approximating the Standard Thermodynamic Functions of Solids

Abstract: The aim of this work is to offer an universal analytical description of the standard thermodynamic functions (primarily, CP°(T), S°(T), H°(T) – H°(Tr)), of solids with accuracy corresponding to experimental measurements. The main advantage of a semiempirical method of approximation under consideration consists in nonstandard usage of a linear combination of well-known thermodynamic functions of the harmonic oscillator (Planck–Einstein functions) unadjusted to the difference between isobaric and isochoric values. The article provides a description of the method, a brief theoretical analysis relating to its justification and opportunities, and examples of specific applications. The article focuses on the problem related to the practical application of thermodynamic data, the problem of standard representation of standard thermodynamic functions themselves. If the substance under investigations does not undergo phase transformations within the temperature interval (0 to T) K and the reference temperature Tr ...

Effects of Four Important Factors on the Measured Minimum Miscibility Pressure and First-Contact Miscibility Pressure

Abstract: The vanishing interfacial tension (VIT) technique is applied to determine the minimum miscibility pressures (MMPs) and first-contact miscibility pressures (Pmax) of five light crude oil–CO2 systems from the measured equilibrium interfacial tensions (IFTs) at different equilibrium pressures. The equilibrium IFTs are measured under various experimental conditions by applying the axisymmetric drop shape analysis technique for the pendant drop case. It is found that in each IFT test, the measured equilibrium IFT is reduced almost linearly with the equilibrium pressure in two pressure ranges. The MMP of each light crude oil–CO2 system is thus determined from the measured equilibrium IFTs in range I by applying the VIT technique. The first-contact miscibility pressure (Pmax) of each light crude oil–CO2 system is extrapolated from the measured equilibrium IFTs in range II. Moreover, the test temperature, crude oil composition (dead/live oil), gas composition (pure/impure CO2), and initial gas–oil ratio (GOR) are...

Volumetric and Viscometric Behavior of Binary Systems 2-Butanol + PEG 200, + PEG 400, + Tetraethylene Glycol Dimethyl Ether, and + N-Methyl-2-pyrrolidone

Abstract: Experimental data on densities, viscosities, and refractive indices of binary mixtures with 2-butanol and polyethylene glycols of different molecular weights, tetraethylene glycol dimethyl ether, or N-methyl-2-pyrrolidone, were determined in the temperature interval from 288.15 K to 323.15 K and at atmospheric pressure. Excess molar volumes, viscosity deviations, and deviations in refractive indices were computed from these data and correlated with the Redlich–Kister polynomial equation. The obtained results allowed the interpretation of specific inter- and intramolecular interactions.

Correlation for the Viscosity of Normal Hydrogen Obtained from Symbolic Regression

Abstract: We report the results of a symbolic-regression methodology to obtain both the functional form and the coefficients for a wide-ranging correlation for the viscosity of normal hydrogen. The correlation covers the temperature range from the triple-point temperature to 1000 K and pressures up to 200 MPa and extrapolates in a physically reasonable manner to 2000 K. The estimated uncertainty is 4 % for the saturated liquid from the triple point to 31 K, with larger deviations as the critical region is approached. The estimated uncertainty is 4 % for the supercritical fluid phase at pressures to 200 MPa. For the limited range of 200 K to 400 K at pressures up to 0.1 MPa, the uncertainty is 0.1 %.

γ-Fe2O3 Nanoparticles Encapsulated Millimeter-Sized Magnetic Chitosan Beads for Removal of Cr(VI) from Water: Thermodynamics, Kinetics, Regeneration, and Uptake Mechanisms

Abstract: Magnetically separable millimeter-sized chitosan beads containing nanosized γ-Fe2O3 were prepared for Cr(VI) removal. The magnetism of the beads arises from the γ-Fe2O3 nanoparticles, by which the sorbent can be easily recovered by the application of an external magnetic field. Various factors influencing the sorption behavior such as pH, temperature, contact time, initial concentration of Cr(VI), and coexisting anions were systematically studied. The time-dependent Cr(VI) sorption data were well described by pseudo-second-order kinetic model. The best interpretation for the equilibrium data was the Freundlich isotherm, and the maximum sorption capacity achieved was 106.5 mg/g at an initial concentration of 200 ppm and pH 5. Thermodynamic parameters of the sorption process were also calculated, which revealed that the sorption of Cr(VI) onto γ-Fe2O3–chitosan beads was spontaneous and exothermic. The sorbed Cr(VI) can be effectively removed from the sorbent with 0.1 M NaOH. The regeneration of the sorbents...

Thermophysical Properties of the Pure Ionic Liquid 1-Butyl-1-methylpyrrolidinium Dicyanamide and Its Binary Mixtures with Alcohols

Abstract: Experimental density, speed of sound, viscosity, and refractive index data for the pure ionic liquid 1-butyl-1-methylpyrrolidinium dicyanamide, [BMpyr][dca], are reported from T = (293.15 to 343.15) K, together with the molar isobaric heat capacity from T = (293.15 to 333.15) K. Moreover, a thermal analysis was carried out for the pure ionic liquid using a differential scanning calorimetry. The density, speed of sound, refractive index, and molar isobaric heat capacity data were fitted to a simple polynomial (first and/or second order), while viscosity data were fitted to the Vogel–Fulcher–Tamman (VFT) equation. From the experimental density values, the thermal expansion coefficient was also calculated. For the binary systems {1-propanol, or 2-propanol, or 1-butanol + [BMpyr][dca]}, density, speed of sound, and refractive index data were also measured over the whole composition range at T = (298.15, 313.15 and 328.15) K and p = 0.1 MPa. From these data, the excess molar volumes and excess molar isentropic...

Solubilization Behavior of Paracetamol in Transcutol–Water Mixtures at (298.15 to 333.15) K

Abstract: The solubilization behavior of paracetamol (PCT) in a diethylene glycol monoethyl ether (Transcutol)–water mixture at (298.15 to 333.15) K is not reported in literature so far. Therefore, attempts were made to investigate the solubilization behavior of PCT in monosolvents and various Transcutol–water mixtures at the temperature range of (298.15 to 333.15) K. The mole fraction solubility of PCT was determined by reported shake flask method. The experimental solubility data of PCT in monosolvents and various Transcutol–water mixtures were found to be correlated well with the modified Apelblat model with the correlation coefficients in the range of 0.996 to 0.999. The solubility of PCT was found to be increased significantly with the increase in temperature and mass fraction of Transcutol. The mole fraction solubility of PCT was found to be highest in pure Transcutol (0.111 at 298.15 K) as compared to water and other cosolvent mixtures. The positive values of enthalpies and entropies indicated that the disso...

On the High-Pressure Solubilities of Carbon Dioxide in Several Ionic Liquids

Abstract: The solubility of carbon dioxide in nine ionic liquids (ILs), at 298 K, 313 K, and 333 K and pressures up to 9 MPa, is presented. The solubility of CO2 in the selected ILs increases with increasing pressure and decreases with increasing temperature, as expected. The effect of several different anions on the solubility of CO2 with a common 1-ethyl-3-methylimidazolium cation is studied in this work. The anions compared were hydrogen sulfate ([emim][HSO4]), methylsulfate ([emim][MeSO4]), methane sulfonate ([emim][MeSO3]), thiocyanate ([emim][SCN]), and diethylphosphate ([emim][DEP]). The results for 1-ethyl-3-methylimidazolium hydrogen sulfate are particularly interesting and can be explained based on the stronger attractive interactions between the IL and CO2, which is supported by quantum calculations. Other ILs investigated were ethyl(tributyl)phosphonium diethylphosphate ([P2444][DEP]), 1-hexyl-3-methylimidazolium trifluoromethane sulfonate ([hmim][OTf]), 1-(2-hydroxyethyl)-3-methylimidazolium trifluoroa...