Search results for "Supercritical fluids"
showing 10 items of 13 documents
Supercritical Assisted Atomization: Polyvinylpyrrolidone as Carrier for Drugs with Poor Solubility in Water
2013
Supercritical assisted atomization (SAA) is an efficient technique to produce microparticles and composite microspheres formed by polymers and pharmaceutical compounds. In this work polyvinylpyrrolidone (PVP) was proposed as carrier for pharmaceutical compounds that show a poor solubility in water medium. Indeed, this polymer is hydrosoluble and can be generally used to enhance the dissolution rate of hydrophobic compounds when finely dispersed in it. However, it is difficult to obtain coprecipitates with a uniform dispersion of the active molecule using other micronization techniques. The experiments were performed using ethanol as solvent; SAA plant was operated at 40°C and 76 bar in the …
Advances and Perspectives of Supercritical Fluid Technology
2013
1 Dipartimento di Ingegneria Industriale, Universita di Salerno, Salerno, 84084 Fisciano, Italy 2 Departamento de Ingenieŕia Quimica, Universidad de Castilla-La Mancha, 13004 Ciudad Real, Spain 3 Department of Agricultural, Food & Nutritional Sciences, University of Alberta, Edmonton, AB, Canada T6G 2P5 4Dipartimento di Ingegneria Chimica, Gestionale, Informatica, Meccanica, Universita di Palermo, 90128 Palermo, Italy
Stability and extraction of bioactive sulfur compounds from Allium genus processed by traditional and innovative technologies
2017
Abstract Since ancient times, species from the Allium genus have been used in both culinary and medicinal applications. The health promoting properties, with well documented “evidence-based” studies, were attributed to the genus’ high content of bioactive organosulfur compounds. For these reasons, the organosulfur compounds have attracted interest in both food and pharmaceutical industries to be used as additives or supplements. Therefore, improvement in the extraction and stability during processing and storage of these molecules is crucial. The presented review documents the effects of traditional and innovative processing techniques on the extraction and stability of organosulfur compoun…
Experimental P-T-ro Measurements of Supercritical Mixtures of Carbon Dioxide, Carbon Monoxide, and Hydrogen and Semiquantitative Estimation of Their …
2007
The P-T-ρ behavior of the CO2-CO-H2 system was studied in the supercritical region under operative conditions close to those adopted to perform hydrogenation and hydroformylation reactions in dense CO 2, thus providing new interesting information on this fluid mixture. Experiments were performed in a fixed volume reactor in the temperature range from 298 K to 343 K changing the density and the composition of the fluid phase. The one-component (Hildebrand) solubility parameter of the mixture was estimated from experimentally measured P vs T profiles, and its dependence on the density and composition of the system was analyzed to study the antisolvent effect of the permanent gases. We have fo…
A Novel Gas Chromatographic Method to Measure Sorption of Dense Gases into Polymers
2006
A novel experimental approach to determine the solubility of gaseous compounds inside polymers is here described. The method is based on the gas chromatographic determination of the composition of the fluid phase at equilibrium with the polymer. To take into account the effect of the volume swelling on the measurement a suitable probe, nonabsorbable by the polymer, was added to the fluid phase. Under the adopted configuration the apparatus can operate up to 35 MPa and 80°C. This experimental technique has been used to determine the solubility of carbon dioxide in poly(vinylidene fluoride) using argon as a probe. The latter was chosen because it is negligibly absorbed by the polymer and does…
Supercritical fluid crystallization of adipic acid using urea as habit modifier
2008
The crystal morphology of adipic acid mediated by the action of urea as additive has been investigated using the supercritical antisolvent precipitation (SAS). The process was performed using acetone and carbon dioxide as solvent and antisolvent, respectively. The effect of urea concentration in the liquid solution and of precipitation pressure on the crystal habit was investigated; the products were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), and infrared spectrometry (FT-IR). Urea was found to be very effective in modifying the crystal habit of adipic acid from needle-like shape with a length of several hun…
Polymerization of methyl methacrylate through ionizing radiation in CO2-based dense systems
2000
Herein, we report the use of ionizing radiation to induce a dispersion polymerization reaction in dense CO2. As a model system, the polymerization of methyl methacrylate in the presence of poly(dimethylsiloxane) stabilizers was investigated. It was demonstrated that the dose plays the key role in the progress of the reaction and in the morphology of the resulting polymer. Dispersion polymerization carried out in the presence of mono- and bifunctionalized surfactants gave differently structured polymers. The polymers obtained have been characterized by scanning electron microscopy, solubility tests, and gel permeation chromatography, and the molecular structure has been related to dynamic me…
Supercritical Antisolvent Extraction of Bioactive Compounds from Mango by-Products
2013
USE OF SUPERCRITICAL CO2 AS DISSOLVED GAS FOR THE ATOMIZATION OF ETHANOL
2011
Supercritical dissolved gas atomization (SDGA) is an atomization process in which carbon dioxide at temperatures and pressures above its critical point is used as atomizing gas. In this work SDGA has been experimentally studied when ethanol is used as the liquid to be atomized. The spray characteristics in terms of droplets size and distribution have been investigated using a droplet size analyzer based on a laser diffraction method. Very narrow droplet size distributions were produced down to 2.5 μm. The main parameter that influences the droplets size is the gas to liquid mass ratio. From the point of view of the atomization mechanism, mean droplet diameter is mainly influenced by the two…
Use of supercritical CO2 and N2 as dissolved gases for the atomization of ethanol and water
2012
Supercritical dissolved gas atomization (SDGA) is an atomization process in which a gas at temperatures and pressures above the critical point is used as the atomizing medium. The concept of SDGA has been applied mainly using CO 2 as atomizing gas in various processes developed for the production of fine particles of pharmaceuticals, polymers, and chemical products and for the atomization of fuels. In this work, SDGA, using ethanol and water as the liquids to be atomized, has been experimentally studied. The spray characteristics, in terms of droplet size and distribution, have been investigated using a laser diffraction analyzer. Ethanol has been chosen due to the large miscibility with CO…