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Ethanol Mixtures (ethanol + mixture)
Selected AbstractsNear-critical carbon dioxide extraction and liquid chromatography determination of UV filters in solid cosmetic samples: A green analytical procedureJOURNAL OF SEPARATION SCIENCE, JSS, Issue 17 2005Amparo Salvador Abstract Near-critical carbon dioxide extraction of four UV filters used as sunscreens in lipsticks and makeup formulations is reported. Extraction parameters were optimized. Efficient recoveries were obtained after 15 min of dynamic extraction with a 80:20 CO2/ethanol mixture at 300 atm and 54°C, using a 1.8 mL/min flow rate. Extracts were collected in ethanol, and appropriately diluted with ethanol and 1% acetic acid to obtain a 70:30 v/v ethanol/1% acetic acid solution. The four UV filters were determined by LC with gradient elution using ethanol/1% acetic acid as mobile phase. The accuracy of the analytical procedure was estimated by comparing the results with those obtained by methods based on classical extraction. The proposed method only requires the use of CO2, ethanol and acetic acid avoiding the use of more toxic organic solvents, thus it could be considered as both operator and environment friendly. [source] Supercritical Carbon Dioxide-Induced Phase Changes in (Ionic Liquid, Water and Ethanol Mixture) Solutions: Application to Biphasic Catalysis.CHEMPHYSCHEM, Issue 5 2003Vesna Najdanovic-Visak The best of both worlds: Phase changes in ionic liquid + water systems, induced by addition of ethanol and supercritical carbon dioxide, allow reaction cycles to proceed as depicted, combining the high rates of one-phase conditions with easy separation of products; characteristic of biphasic catalysis. The (usually slow) epoxidation of isophorone by hydrogen peroxide, catalysed by sodium hydroxide, was rapidly carried out in these conditions, with complete recovery of the reaction product by supercritical CO2 decompression. [source] High-Zirconium-Content Nano-Sized Bimodal Mesoporous SilicasEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2006David Ortiz de Zárate Abstract Silica-based nanoparticulated bimodal mesoporous materials with high Zr content (43 , Si/Zr , 4) have been synthesized by a one-pot surfactant-assisted procedure from a hydroalcoholic medium using a cationic surfactant (CTMABr = cetyltrimethylammonium bromide) as structure-directing agent, and starting from molecular atrane complexes of Zr and Si as hydrolytic inorganic precursors. This preparative technique allows optimization of the dispersion of the Zr guest species in the silica walls. The bimodal mesoporous nature of the final high surface area nano-sized materials is confirmed by XRD, TEM, and N2 adsorption,desorption isotherms. The small intraparticle mesopore system (with pore sizes around 2,3 nm) is due to the supramolecular templating effect of the surfactant, while the large mesopores (around 12,24 nm) have their origin in the packing voids generated by aggregation of the primary nanometric mesoporous particles. The basicity of the reaction medium seems to be a key parameter in the definition of this last pore system. The effects induced by the progressive incorporation of Zr atoms on the mesostructure have been examined, and the local environment of the Zr sites in the framework has been investigated by UV/Vis spectroscopy. Observations based on the consequences of post-treatments of the as-synthesized materials with HCl/ethanol mixtures corroborate that the atrane method leads to Zr-rich materials showing enhanced site accessibility and high chemical homogeneity throughout the pore walls. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] A new technique for foaming submicron size poly(methyl methacrylate) particlesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2007Hiroyuki Ogawa Abstract About 0.7,2 ,m diameter poly (methyl methacrylate) (PMMA) foamed particles were prepared via thermally induced phase separation (TIPS) from a PMMA/ethanol mixture and vacuum dried. It was found that ethanol, known to be a poor solvent to PMMA, could dissolve PMMA when the temperature was over 60°C. The solubility of PMMA (Mw = 15,000 and Mw = 120,000) in ethanol was measured and was found to increase as the temperature increased. PMMA particles on the scale of submicron and single micron diameter could be precipitated from the PMMA/ethanol solution by temperature quenching. Then, since the precipitated particles contained a certain amount of ethanol, the precipitated particles could be foamed using the ethanol as a foaming agent in a vacuum drying process. Vacuum drying at temperatures slightly below the glass transition temperature of the polymer could make the particles foam. The effects of foaming temperature and the molecular weight of the polymer on the size of foamed particles were investigated. The experimental results showed that the vapor pressure and the molecular weight of the polymer are key factors determining the expandability of the micro particles. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] Supercritical fluid extraction of walnut kernel oilEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 7 2006Sema Salg Abstract The objective of this study was to investigate the effects of the main process parameters on supercritical fluid extraction of walnut (Juglans regia,L.) kernel oil. The recovery of walnut kernel oil was performed in a green and high-tech separation process. CO2 and CO2 +,ethanol mixtures were used as the supercritical solvent. The extraction was carried out at operating pressures of 30, 40 and 50,MPa, operating temperatures of 313, 323 and 333,K, mean particle sizes of 1.78×10,4, 3.03×10,4, 4.78×10,4, 7.00×10,4 and 9.00×10,4,m, supercritical CO2 (SC CO2) flow rates of 1.67×10,8, 3.33×10,8, 6.67×10,8 and 13.33×10,8,m3/s and entrainer (ethanol) concentrations of 2, 4, 8 and 12,vol-%. Maximum extraction yield and oil solubility in SC CO2 obtained at 50,MPa, 333,K, 9.00×10,4,m, 3.33×10,4,m3/h were 0.65,kg oil/kg of dry sample and 37.16,g oil/kg CO2, respectively. The results obtained in this study showed that the crossover pressure effect of walnut kernel oil was at 30,MPa. At 30,MPa and 313,K, the obtained extraction yields above 4,vol-% ethanol reached the organic solvent extraction yield of 68.5,kg oil/kg dry sample. Extraction time was decreased significantly because of the higher solubility of walnut kernel oil in SC CO2 +,ethanol mixtures. [source] MODELING OF SWEET, BITTER AND IRRITANT SENSATIONS AND THEIR INTERACTIONS ELICITED BY MODEL ICE WINESJOURNAL OF SENSORY STUDIES, Issue 5 2006CANAN NURGEL ABSTRACT Interactions between taste and irritant sensations elicited by model ice wine solutions were investigated, including the use of U and ,, models for predicting the perceived intensity of these sensory interactions. Fifteen solutions of varying ethanol and sugar concentrations representative of commercial ice wine values were evaluated in two trials by a trained sensory panel (n = 12) for perceived sweetness, bitterness and heat intensities. Sweetness perception of lower sugar-concentration level in ice wine model solution was affected by ethanol concentration. The sweetness intensities of the sugar and ethanol mixtures are higher than the sweetness intensities of sugar solutions. The ,, index indicates a slight synergy between ethanol and sugar on sweetness perception. The bitterness intensities elicited by ethanol,sugar mixtures are lower than those elicited by unmixed ethanol solutions. The ,, index indicates inhibition of ethanol and sugar perception on bitterness perception. Suppression of heat sensation was found in model base wine solutions across sugar and ethanol concentrations. [source] Vibrational coupling as diagnostic for intramolecular hydrogen bonds of carbohydrates in aqueous solutionBIOPOLYMERS, Issue 1 2002Pedro Carmona Abstract The coupling of ,CO and ,OD vibrations in the 1200,900 cm,1 IR range leads to band shifting in opposite directions, which provides information on intramolecular hydrogen bonding of carbohydrates in aqueous solution. The aqueous solution IR spectra of 2-acetamide-1,6-anhydro-2-deoxy- D -glucopyranose and cis-1,2-cyclopentanediol and tetrahydrofuran,ethanol mixtures are reported. Frequency upshifting upon deuteration is observed for the ,CO bands of both a hydrogen bond acceptor and donor in ether,hydroxyl and hydroxyl,hydroxyl contacts. The 1200,900 cm,1 range can be used to reveal the presence of intramolecular hydrogen bonds in aqueous carbohydrates, unlike the OH stretching region, which cannot be used in this sense due to carbohydrate band masking by the strong ,OH IR absorption of water. © 2002 John Wiley & Sons, Inc. Biopolymers (Biospectroscopy) 67: 20,25, 2002; DOI 10.1002/bip.10024 [source] Micronization of lysozyme by supercritical assisted atomizationBIOTECHNOLOGY & BIOENGINEERING, Issue 6 2009Renata Adami Abstract Supercritical Assisted Atomization (SAA) has been used to produce lysozyme microparticles. Lysozyme has been micronized using water, buffered water at pH 6.2 and water,ethanol mixtures at different volume percentages. Precipitated lysozyme particles were spherical, with a narrow particle size distribution (PSD) ranging from 0.1 to 4,µm. The concentration of lysozyme in the liquid solvent mixture had a nonlinear effect on the particle distribution, with an increase of the X0.9 from about 1 to 3,µm varying the enzyme concentration from 5 to 20,mg/mL. Precipitation temperature was set as low as possible to avoid enzyme degradation. High-performance liquid chromatography analysis showed no degradation of lysozyme and the enzyme activity, measured by turbidimetric enzymatic assay, only slightly decreased after SAA processing. Depending on the process conditions lysozyme retained from 95% to 100% of the biological activity compared to the untreated enzyme. Biotechnol. Bioeng. 2009; 104: 1162,1170. © 2009 Wiley Periodicals, Inc. [source] Factorial designed experiment to study the effects of excipients on the mechanical properties of pelletsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 10 2006Abraham B. Bashaiwoldu The aim of this work was to determine the effects of formulation factors on the mechanical properties of pellets produced by the process of extrusion and spheronisation. A range of properties from a simple fracture load to detailed load/displacement curves were used to study the effects of the levels of lactose monohydrate and glyceryl monostearate on the mechanical properties of pellets in terms of their surface tensile strength, pellet deformability and linear strain. A series of independent 22 -factorial designs were employed to establish the relationships between composition of the formulations and pellet properties, whereby the concept of an excess variable was explored. It was found that the spheronisation aid used, microcrystalline cellulose, is the domineering factor in most mechanical properties studied, except for the surface tensile strength, which decreased significantly with an increase in glyceryl monostearate concentration. The change in binder liquid from water to a water/ethanol mixture further changed the behaviour of the systems significantly. The assumption of an excess variable being less critical for the statistical outcome of a factorial experiment has not been found feasible for the systems studied. [source] Pd,Ag membranes for auto-thermal ethanol reformingASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2010Silvano Tosti Abstract The auto-thermal ethanol reforming was carried out at 200 kPa by a two-step process consisting of a traditional reformer operating at high temperature (700,740 °C) and a Pd,Ag multitube membrane module where the separation of hydrogen took place at 350,380 °C. The membrane module was a bundle of 11 thin-wall Pd,Ag tubes of wall thickness 50,60 µm, diameter 10 mm, and length 270 mm: permeation tests were performed at 300,395 °C with lumen pressure of 150,200 kPa, and nitrogen sweep flow rates in the shell side ranged from 10 to 30 l min,1 at atmospheric pressure. A hydrogen permeance Pe = 1.317 × 10,2 exp (,3.622 × 103/T(K)) mol m,2 s,1 Pa,0.5 was measured and complete hydrogen selectivity was verified. A water/ethanol mixture of molar ratio 2.50/1.00 was used as feed stream for carrying out ethanol reforming in the traditional fixed-bed reactor filled with a Ni on alumina catalyst. As a second step, the water gas shift (WGS) membrane reaction was carried out in the multitube membrane reactor: the Pd,Ag alloy of the membrane tubes worked for both catalyzing the reaction and for separating all the hydrogen produced in the reformer and in the membrane reactor itself. The hydrogen separated through the membrane was collected in the shell side of the membrane module: by operating with a water/ethanol feed flow rate of 200 g h,1, up to 1.2 l min,1 of pure hydrogen was produced. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] | |||||||||||||