Ethanol-water Mixed Solvent Research Articles

Conductometric study of nickel chloride in ethanol-water mixed solvent media at various temperatures

The conductivity measurement of nickel chloride has been done in binary solvent of the ethanol-water system. The different percentage of ethanol including 10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 (v/v) has been chosen as binary solvents. The concentration of the electrolyte in the prepared solutions varies from 0.008 to 0.1 mol.l-1 for temperatures 298.15 K, 303.15 K and 308.15 K. The conductivity of the electrolyte decreases with increase in ethanol content in the solvent at a particular temperature, which is due to the decrease in dielectric constant of the medium. The conductivity increases with increase in temperature and concentration, due to increase in mobility of ions and number of ions from observed electrolyte respectively. DOI: http://dx.doi.org/10.3126/bibechana.v12i0.11789BIBECHANA 12 (2015) 128-134

Determination and modeling of activity coefficients of cobalt chloride in the (water + ethanol) mixed solvent system by potentiometric method at 298.15 K

In this work, the thermodynamic properties of (CoCl2+C2H5OH+H2O) system were investigated by potentiometric method and based on Pitzer ion interaction model. For this purpose, primarily the mean activity coefficients of CoCl2 in pure water and ethanol–water mixture solvent were determined using a galvanic cell without liquid junction potential of type: Co2+-ISE|CoCl2 (m), C2H5OH (wt.%), H2O (100-wt.%) |Ag·AgCl. The measurements were performed at T=298.15K and at total ionic strengths from 0.001 to 6.000mol·kg−1 in various ethanol–water mixed solvent systems containing 0, 10, 20, 30, 40 and 50% mass fractions of ethanol. The mean activity coefficients measured were correlated with Pitzer ion interaction model and the Pitzer adjustable parameters were determined. Then these parameters were used to calculate the thermodynamics properties for under investigated system. The results showed that the Pitzer ion interaction model can satisfactory describe the investigated system. The modified three-characteristic-parameter correlation (TCPC) model was applied to correlate the experimental activity coefficient data for under investigation electrolyte system, too. The results showed that the modified TCPC model also was suitable in the case of the mixed solvent system.

Roles of the amino group of purine bases in the thermodynamic stability of DNA base pairing.

The energetic aspects of hydrogen-bonded base-pair interactions are important for the design of functional nucleotide analogs and for practical applications of oligonucleotides. The present study investigated the contribution of the 2-amino group of DNA purine bases to the thermodynamic stability of oligonucleotide duplexes under different salt and solvent conditions, using 2'-deoxyriboinosine (I) and 2'-deoxyribo-2,6-diaminopurine (D) as non-canonical nucleotides. The stability of DNA duplexes was changed by substitution of a single base pair in the following order: G•C > D•T ≈ I•C > A•T > G•T > I•T. The apparent stabilization energy due to the presence of the 2-amino group of G and D varied depending on the salt concentration, and decreased in the water-ethanol mixed solvent. The effects of salt concentration on the thermodynamics of DNA duplexes were found to be partially sequence-dependent, and the 2-amino group of the purine bases might have an influence on the binding of ions to DNA through the formation of a stable base-paired structure. Our results also showed that physiological salt conditions were energetically favorable for complementary base recognition, and conversely, low salt concentration media and ethanol-containing solvents were effective for low stringency oligonucleotide hybridization, in the context of conditions employed in this study.

Production of phenols from catalytic conversion of lignin over a tungsten phosphide catalyst

Production of phenols from alkaline lignin over a tungsten phosphide catalyst in a hot compressed water–ethanol mixed solvent is examined. The small molecular products mainly consist of five phenols, i.e. 2-methoxy-phenol (guaiacol), 2-methoxy-4-methyl-phenol, 2-methoxy-4-ethyl-phenol, 2-methoxy-4-acetyl-phenol and 2-methoxy-4-propyl-phenol. The activated carbon supported catalyst gives the highest overall phenols yield, 67.0mg/g lignin, while the catalysts with other supports exhibit much lower overall yield. Ni and Fe doping of the tungsten phosphide improve phenols selectivity but lower the overall phenols yield. In addition, the result of MALDI-TOF analysis indicates that a longer reaction time leads to the formation of polymers with molecular weights of m/z 701–1040 due to the re-polymerization reactions. Therefore, the yield of the monophenols decreases with the increase of the reaction time.

LiCoPO4 and Li2CoSiO4 Nanoparticles Synthesis by Supercritical Fluid Process for Lithium Ion Battery Application

In recent years, transition metal polyanionic compounds such as phosphates and silicates are considered as promising positive electrode materials for lithium-ion batteries. These members of the lithium metal polyanion family have been a major focus of research for reasons of high safety, low cost and low environmental impact. Among, metal phosphate cathode material, LiCoPO4 electrode materials have received considerable attention for the application in lithium secondary batteries due to its high stability, non toxicity, good charge/discharge capabilities and cheap cost. Recently, polyanion-containing frameworks are of great research interest in the area of lithium ion batteries, because, these materials can reversibly insert/extract two lithium ions per formula unit would help to increase the capacity and energy density. Regarding this, silicates with the general formula Li2MSiO4 (M=Mn, Fe and Co) have been considered as potential lithium insertion/ extraction cathodes. Among silicates, Li2CoSiO4 is an attractive cathode due to its high operating voltage. In this work, we have used supercritical fluid process for the synthesis of LiCoPO4 and Li2CoSiO4 nanoparticles and are investigated for lithium ion battery applications. LiCoPO4 and Li2CoSiO4 nanoparticles were synthesized from LiOH.H2O/Lithum acetyl acetonate, CoCl3.6H2O/C4H6CoO4.4H2O and H3PO4/TEOS in molar ratio of 1:1:1 for LiCoPO4 and 4:1:1 for Li2CoSiO4 nanoparticles via supercritical fluid process. Cheap solvents such as water, ethanol and water-ethanol mixed solvents were used to prepare precursor solutions and reducing agents were also used in the synthesis. Supercritical synthesis was carried out at 400-450oC for about 5-10 min of reaction time. Then, the products were washed thoroughly in water and ethanol followed by vacuum dry for overnight. The as-synthesized LiCoPO4 and Li2CoSiO4 nanoparticles showed 20-150 nm in diameter, which was analysed by transmission electron microscopy (TEM). Further, LiCoPO4 and Li2CoSiO4 nanoparticles were systematically characterized using powder X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), scanning transmission electron microscopy (STEM), energy dispersive spectroscopy (EDS) and charge-discharge measurements. The discharge capacities of 80-110 mAhg-1 for LiCoPO4 nanoparticles and 40-110 mAhg-1 for Li2CoSiO4 nanoparticles were observed. The electrochemical property was measured by galvanostatic discharge method using 1M LiPF6 mixed in EC:DEC as electrolyte. The electrode was prepared using 10 wt% PTFE as binder. The weight ratio of active material:AB:PTFE are 80:10:10.

Osmotic and activity coefficient investigation on the CsNO3 + methanol + water and CsNO3 + ethanol + water ternary systems at 298.15 K

The mean ionic activity and osmotic coefficients of CsNO3 in methanol–water and ethanol–water mixed solvent at 298.15K have been determined herein utilizing the potentiometric method. The potential measurements were carried out on a cell, Cs-ISE/CsNO3 (m), ROH (w), H2O (1−w)/NO3-ISE, in the mixed solvent containing w=(0.00, 0.10, 0.20, and 0.30) mass fraction of alcohol. The activity coefficients were calculated from the experimental E value and fitted via the extended Debye–Hückel, Pitzer and the modified Pitzer model equations. The osmotic coefficients, the primary hydration number (nhydr), excess Gibbs free energy and standard Gibbs energies of transference of CsNO3 from the water to the methanol+water or ethanol+water mixtures have also been discussed.

Effect of hydration layer on the structure of thermo‐sensitive nanocapsules

ABSTRACTA thermo‐sensitive nanocapsule, containing the hydration layer, was synthesized through introducing N‐isopropylacrylamide into the system of styrene miniemulsion polymerization and hexadecane as liquid template. The properties and content of the water in the hydration layer were investigated by differential scanning calorimetry. With dynamic light scattering and transmission electron microscope, the effects of temperature and solvent on the particle size and morphologies were studied. The results showed that the increase of temperature and the ethanol–water mixed solvent could decrease the thickness of hydration layer and caused the polymer chain in the shell coil‐to‐globule transition, which switched on the pathway to loading and releasing substances in the nanocapsules. By using UV‐visible spectroscopy to monitor the tracer, the diffusion coefficients were determined and verified the switching process above. In addition, the ethanol–water molecule cluster can form a stable associative structure around ethanol mole fraction of 0.4, and destroyed the hydration of the hydrophilic group. The solvent interactions were proved to be the main driving force for the coil‐to‐globule transition of poly(N‐isopropylacrylamide). Moreover, an appropriate latex particle size should exclude the hydration layer but stable dispersed in the solvent was suggested. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40589.

Modeling and Simulation of Thermodynamic Properties of l-Alanyl-l-Glutamine in Different Solvents

The solubility of l-alanyl-l-glutamine (Ala-Gln) in pure water and ethanol–water mixed solvents was measured using a synthetic method from 283.15 to 313.15 K. Molecular dynamics simulation was carried out to explain the effect of ethanol content on the solubility of Ala-Gln. The radial distribution function was used to evaluate the interactions between solute molecules and solvent molecules. The solubility data was correlated by four thermodynamic models, including the hybrid model, Wilson model, NRTL model, and UNIQUAC model. It was found that the NRTL model could give better correlation results than the other models. The dissolution properties of Ala-Gln solutions, including the free Gibbs energy, the dissolution enthalpy, and the dissolution entropy, were calculated by using the modified van’t Hoff equation.

Surfactant-free solvothermal synthesis and optical characterization of Bi2Fe4O9 in mixed H2O/EtOH solvent

Bi2Fe4O9 powders with different morphology and particle size have been prepared via surfactant-free solvothermal route with water and water–ethanol mixed solvents. The as-synthesized samples were characterized by powder X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and UV–vis spectroscopy. The effect of the solvent on the morphology of Bi2Fe4O9 crystals and the formation process of rod-like microrods and defective crystals were investigated. Rod-like and cubic shape Bi2Fe4O9 crystals could be easily obtained by changing the volume ratios of H2O/EtOH. The results indicate that the rod-like Bi2Fe4O9 crystals could be formed in the more ionic solvent, and the anisotropic nature of the crystal structure may be responsible for the formation of rod-shape. In addition, the optical properties and photocatalytic activity of the Bi2Fe4O9 samples were investigated. The lower photocatalytic activity of Bi2Fe4O9 microrods could be attributed to their larger particle size, smaller specific surface areas and smaller bandgap.

Fabrication of hierarchical zeolite 4A microspheres with improved adsorption capacity to bromofluoropropene and their fire suppression performance

Novel hierarchical zeolite 4A microspheres consisted of interconnected nanoflakes were successfully prepared from Kaolin precursor in a simple ethanol–water mixed solvent system. While in aqueous solution without ethanol, only commonly cubic particles were obtained. It was found that the concentration of ethanol in the solvent was crucial to the production of microspheres. There existed an optimized concentration range of ethanol where microspheres were fabricated with highly yield. Thus-prepared single-phase zeolite 4A microspheres exhibited a large Brunauer–Emmett–Teller (BET) surface area of 666.9m2/g, pore volume of 0.0147cm3/g and average pore size of 6.9nm. The porous spheres exhibited an adsorption capacity of 8.7wt.% to a clean gas fire suppressant of 2-bromo-3,3,3-trifluoropropene (BTP) at room temperature, much higher than that of conventional cubic zeolite 4A particles (4.2wt.%). Bench scale fire tests revealed that these zeolite 4A microspheres soaked with BTP exhibited much better performance than that of cubic counterparts in suppressing methane/air coflowing diffusion flames in cup burner, with the fire extinguishing concentration decreased by more than 20% at the comparable powder discharging rate. Such an improvement could be ascribed to the larger surface area and higher adsorption capacity of zeolite 4A microspheres.

Separation of NMP/water mixtures by nanocomposite PEBA membrane: Part I. Membrane synthesis, characterization and pervaporation performance

Novel composite poly(ether-block-amide) (PEBA-2533) membranes were prepared in 90:10v/v ethanol–water mixed solvent system for pervaporation of n-methyl pyrrolidone (NMP)/water mixtures. Hydrophilic 4A zeolite was incorporated to the extent of 10–40% of polymer weight to enhance separation properties. The synthesized membranes were crosslinked with 2% v/v 2, 4-toluylene-diisocyanate (TDI) in hexane medium for 4h to reduce degree of swelling and improve selective nature with respect to water. Sorption studies were carried out in pure water, NMP and binary mixtures of varying compositions to establish membrane–liquid interactions. Membranes were characterized by FTIR, XRD and SEM to study formation of new functional groups and intermolecular interactions, degree of crystallinity and d-spacing, besides morphologies of surface and cross-section of the composite films, respectively. Effect of feed composition on membrane performance was evaluated using the optimum 30% zeolite-loaded membrane. For a feed mixture containing 2.87wt.% water, a selectivity of 122 at a reasonable flux of 55g/m2h was observed. PEBA-2533 membrane appears to have considerable potential for dewatering of highly polar aprotic solvents owing to its ability to dehydrate NMP to purity levels of >99%. The composite nature of the membrane makes it feasible to fabricate modular configurations for scale-up.

Thermochemical liquefaction of rice husk for bio-oil production in mixed solvent (ethanol–water)

Thermochemical liquefaction characteristics of rice husk in mixed solvent (ethanol–water) were investigated in this study. Compared with pure water or ethanol, the mixed solvent showed synergistic effect at a relatively lower temperature. The highest bio-oil yield was obtained at 533K in ethanol–water mixed solvent (V/V, 5:5) and found to be 21.15%. In pure water and mixed solvent treatments, the yield of bio-oil declined with reaction temperature increasing from 533K to 613K. However, with the pure ethanol as solvent, the bio-oil yield increased firstly and then decreased slightly. In addition, the effects of solid–liquid ratio and solvent filling ratio on the distribution of liquefaction products were also explored with ethanol–water mixed solvent as medium. Higher solid–liquid ratio resulted in lower bio-oil yield, while the increase of solvent filling ratio led to an increase in the bio-oil yield. The compositions of bio-oil from rice husk consisted mainly of phenolic compounds, long-chain alkanes, ketones and esters. Compared with pure water or ethanol, the relative concentration of phenolic compounds in mixed solvent run was higher and reached up to 21.22%.

Environmentally Benign Synthesis of Bi<SUB>2</SUB>S<SUB>3</SUB> Quantum Dot Using Microwave-Assisted Approach

Oleic acid (OA) capped Bi2S3 quantum dots were successfully synthesized using 180 watt microwave power for 5 minutes in water-ethanol mixed solvents containing oleic acid as capping agent. In this approach, the reaction was conducted in ambient air and a much lower temperature than hot injection approach. The OA capped Bi2S3 QDs were characterized by using XRD, TEM, FTIR, UV-Vis and PL. The OA capped Bi2S3 QDs can be readily modified with sodium dodecyl sulfate (SDS) via hydrophobic interaction to improve their solubility in aqueous solution. According to optical properties of the QDs, the modified QD revealed the additional features, such as photothermal therapeutic agent and fluorescent probe.

Effect of Solvent Composition on the Critical Micelle Concentration of Cetylpyridinium Chloride in Ethanol-Water Mixed Solvent Media

The accurate measurement of the specific conductivity of cetylpyridinium chloride in pure water and ethanol-water mixed solvent media containing 0.10, 0.20, 0.30 and 0.40 volume fraction of ethanol at room temperature are reported. The concentrations were varied from ~ 0.005 mol l-1 to ~ 0.0002 mol l-1.The conductivity of cetylpyridinium chloride decreases with the increase in the volume fraction of ethanol. The critical micelle concentration of cetylpyridinium chloride increases with the increase in the volume fraction of ethanol. Nepal Journal of Science and Technology Vol. 13, No. 1 (2012) 89-93 DOI: http://dx.doi.org/10.3126/njst.v13i1.7446

Effects of concentration and solvent composition on the electrical conductivity of sodium bromide in pure water and ethanol-water mixed solvent media

Precise measurements on the conductivity of Sodium Bromide in pure water and ethanol-water mixed solvent media containing 0.10, 0.20, 0.30, 0.40, 0.50 and 0.60 volume fractions of ethanol at room temperature are reported. The concentrations were varied from ~ 0.010 to ~ 0.10 mol.L-1. The results showed a sharp increase in the conductivity with increasing electrolyte concentration. The conductivity of electrolyte decreases with increase in the amount of ethanol.Kathmandu University Journal of Science, Engineering and Technology Vol. 8, No. II, December, 2012, 1-6 DOI: http://dx.doi.org/10.3126/kuset.v8i2.7318

N-Doped lepidocrocite nanotubular arrays: hydrothermal formation from anodic TiO2nanotubes and enhanced visible light photoresponse

New Cs-lepidocrocite nanotubular arrays were successfully prepared from anodically grown TiO2 nanotubes by hydrothermal conversion using CsOH in a water–ethanol mixed solvent. The obtained open nanotubular structure consists of plate-like nano-crystals, reflecting a preferred facet growth of the lepidocrocite with a 2-dimensional layered crystal structure. N-Doping of the Cs-lepidocrocite nanotubular layer was carried out by annealing in NH3 gas. The N-doped sample showed an incident photon to current conversion efficiency (IPCE) of 1.43% at 450 nm, which is 57% higher than conventional N-doped anatase TiO2 nanotubes.

Effect of solvent composition on the critical micelle concentration of sodium deoxycholate in ethanol-water mixed solvent media

The precise measurement of the specific conductivity of sodium deoxycholate in pure water and ethanolwater mixed solvent media containing 0.10 and 0.20 volume fraction of ethanol at 303.15 K are reported. The concentration were varied from ~ 0.01 mol L-1 to ~ 0.0002 mol L-1.The conductivity of sodium deoxycholate decreases with the increase in the volume fraction of ethanol. The critical micelle concentration of sodium deoxycholate increases with the increase in the volume fraction of ethanol. DOI: http://dx.doi.org/10.3126/bibechana.v9i0.7176 BIBECHANA 9 (2013) 63-68

A new, simple hydrothermal synthesis of magnetic nano-octahedrons — Application to hyperthermia cancer cell killing

Surfactant-free magnetic nano-octahedrons were successfully synthesized by the alkaline hydrothermal decomposition of ferric nitrate salt (Fe(NO3)3·9H2O) in a water–ethanol mixed solvent with a variety of alkaline concentrations. High-resolution scanning electron microscope (SEM) pictures demonstrated the formation of octahedron-structured magnetic nanoparticles at a 10 mol/L alkaline concentration. A possible synthesis mechanism of the magnetic nano-octahedron was discussed. An alternating current magnetic field to induce hyperthermia cancer cell killing was investigated. Maximum hyperthermia cancer cell killing (~100%) was found with 10 mol/L alkaline-synthesized nano-octahedrons, whereas that with 2 mol/L alkaline gave ~40%.

Nickel Cobalt Oxide-Single Wall Carbon Nanotube Composite Material for Superior Cycling Stability and High-Performance Supercapacitor Application

The electron conductivity of electrode material has always been a problem that hinders the practical application of supercapacitor. In this contribution, we report a facile synthesis of highly conductive nickel cobalt oxide-single wall carbon nanotube (NiCo2O4–SWCNT) nanocomposite by controlled hydrolysis process in ethanol–water mixed solvent. Ultrafine NiCo2O4 nanocrystals with a diameter around 6–10 nm are formed on the functionalized SWCNT bundles. This novel material not only exhibits a high specific capacitance of 1642 F g–1 within a 0.45 V potential range but also shows an excellent cycling stability of 94.1% retention after 2000 cycles at high mass loading. Our method provides a promising facile and high-performance strategy for supercapacitor electrode application.

Morphology and size control of barium carbonate in ethanol–water mixed solvents

Barium carbonate (BaCO3) particles have been obtained by the precipitation reaction of CO2 bubbles to barium hydroxide [Ba(OH)2] in the ethanol–water mixed solvents. Various morphologies, from rounded peanut, leaf-like, rod, and needle particles, were controlled by the precipitation step, where CO2 gas was fed to Ba(OH)2 in ethanol–water mixed solvent. The CO2 gas as a carbonate source and Ba(OH)2 slurry as a barium ion source are dissolved in the mixed solvents, within the solubility limit, to precipitate. The reactants dissolve progressively while they precipitate to BaCO3. Ba(OH) 2 slurry becomes translucent and opaque while the reaction proceeds. It becomes more opaque, upon which the dissolution of Ba(OH)2 proceeds and BaCO3 precipitates. The opaqueness of the products depends on the particle size of BaCO3 in the product. The characteristics of BaCO3 were confirmed by the X-ray diffraction (XRD), transmission electron microscope (TEM), and electrophoretic light scattering methods. The amount of water in the mixed solvents and of Ba(OH) 2 in the reaction batch is related to the reaction rate in the nucleation and growing step, so that it was possible to control the shape of particles. Based on the understanding of the size and morphology of BaCO3 in the solid/liquid–gas system, it was possible to obtain a well-dispersed average 40-nm BaCO3 colloid.