Supercritical fluids

The aim of this work was to evaluate the potential of supercritical carbon dioxide to extract fatty acid methyl esters (FAME) from the microalgae Nannochloropsis oculata at low temperatures (37 and
55 oC) and pressures (5.9 and 7.6 megapascals (MPa)). A qualitative gas chromatography (GC) analysis showed that the individual FAME extracted varied depending on the co-solvent (methanol or hexane) used with supercritical CO2. Using hexane, FAME compounds produced were similar to those extracted with soxhlet extraction alone while longer chain FAME were produced when methanol was the co-solvent. The effects of pressure and temperature variations were shown to be of statistical significance. The chromatograms produced in this work demonstrate that altering one of these parameters (co-solvent, temperature, pressure) can produce different compounds owing to the tunability of the technique.

The electrospinning of polymers has become a potentially important process for the production of tissue engineering scaffolds. CO2 impregnation of these scaffolds may provide a method for tailoring the chemistry of these relatively high surface area scaffolds without altering their biomimetic architecture. In pursuing this we found that electrospun polycaprolactone (PCL) fibers melt when exposed to supercritical CO2 even at

Supercritical dyeing has risen good expectation in the last few years due to the attractive perspective of complete elimination of water from dyeing processes. A lot of research activities have been developed in the last decade both to deepen the knowledge of the interaction mechanisms between CO2, dye and polymers and to solve the technological problems of the process set-up.

There is an increasing public awareness of the health, environment and safety
hazards associated with the use of organic solvents in food processing and the possible
solvent contamination of the final products. The high cost of organic solvents and the
increasingly stringent environmental regulations together with the new requirements of the medical and food industries for ultra-pure and high added value products have pointed out the need for the development of new and clean technologies for the processing of food products. Supercritical fluid extraction using carbon dioxide as a solvent has provided an excellent alternative to the use of chemical solvents. Over the past three decades, supercritical CO2 has been used for the extraction and isolation of valuable compounds from natural products

The vapour–liquid equilibria of α-pinene, limonene and fenchone, and solubility behaviour of camphor were measured in supercritical carbon dioxide (SC-CO2) as a function of pressure and temperature using the static method. Experiments were carried out in the ...

It is currently impossible to control irrigation at the level of a single plant. Even with drip irrigation, in which emitters could conceivably be placed on a plant-by-plant basis, there is no way to control the amount of water emitted according to the needs of the individual plants. If such a capability were practically available on farms, the result would be a step change in precision agriculture, such that the water input for every plant in a farm (or field) could be optimized. Therefore, we are exploring the possibility of developing a microfluidic system that could be controlled, capillary by capillary, to deliver the needed amount of water to individual plants in a large field. The principal aim is to show proof of concept by building and testing a prototype to produce data suggestive of the potential for multiple individually controllable microfluidic ports along a pressurized tube of water. Hence, in this study we perform experiments using a thermally actuated microvalve for...

Supercritical CO2 extraction has been proved to be a potential tool in the recovery of aroma compounds from different natural sources and in the removal of ethanol from aqueous solutions. In this work, both ideas are combined to develop a two-step process toward the production of a low-alcohol beverage from wine, but maintaining the aroma and the antioxidant activity similar to that of the original wine.First, the recovery of aroma from wine was attained in a countercurrent packed column (white and red wines were investigated) using very low CO2/wine ratios. Then, the aroma-free wine recovered from the bottom of the extraction column was dealcoholized by applying different extraction conditions.The results obtained from these studies permit the design of a two-step countercurrent CO2 extraction process at 9.5 MPa and 313 K, in which the different CO2/wine ratios employed in each step lead to the recovery of aroma or the removal of ethanol. The two-step process was applied to rose wine and the low-alcohol beverage obtained proved to have similar antioxidant activity and similar aroma profile to that of the original wine.► We produce a low-alcohol beverage from wine based on a supercritical process. ► The countercurrent-SFE process is a two-step process. ► First, recovery of aroma using very low CO2/wine ratios. ► Second, dealcoholization of the aroma-free wine. ► Beverage obtained have similar antioxidant activities and aroma to that original wine.

Separation process using supercritical CO 2 to concentrate ethanol from aqueous solution appears to be a promising technology. Knowledge of vapor-liquid equilibria (VLE) for systems consisting of CO 2 , ethanol and water is necessary for designing such separation technique. In this work, The Peng-Robinson equation of state (PR EoS) combined with classical and modified quadratic mixing rules were evaluated in predicting VLE of CO 2 +ethanol, CO 2 +water, ethanol+water and that of CO 2 +ethanol+water system using temperature dependence and independence of binary interaction parameters. For binary systems, evaluation was performed by comparing the calculated values with the literature data at the temperature range of 293.15 – 523.15 K and pressure range of 0.01–17.44 MPa. Using temperature independent parameters, PR EoS – Quadratic and PR EoS-Classical gave average absolute deviations (AAD) in pressure ≤ 3,70% and ≤ 5,46% respectively. PR EoS-Quadratic gave better prediction results than PR EoS-Classical. For ternary CO 2 +Ethanol+Water systems, evaluation was performed at the temperature range of 313.20 –343.20 K and the pressure range of 9.05 –11.3 MPa. The best prediction result of ternary system was obtained by optimized interaction parameter of CO 2 +Water from ternary VLE data and the other parameters from binary VLE data.

The past twenty years has seen an expansion of the “critical fluid” technology platform with respect to using or combining multiple types of unit operations and compressed fluids in both their sub- and supercritical states. Although supercritical fluid extraction (SFE) utilizing supercritical carbon dioxide (SC-CO2) has seen considerable industrial use, the high capitalization cost of building and running such production plants promotes expanding their use and functionality with respect to multi-unit operations and multiple fluids. An evaluation of the current status of implementing such an approach is provided, and a perspective of future needs suggested based on the senior author’s 40 years of experience in critical fluid processing of agriculturally-derived materials and natural products. The use of hot compressed water is no longer limited to just supercritical water processing, but can be advantageously exploited over a wide range of temperatures and appropriate pressures to include extraction and reaction of targeted substrates, including bioactive natural products, biomass conversion for renewable fuels, and synthesis of chemicals. As noted previously, combining SFE with fractionation methods using critical fluids, and/or reaction chemistry in critical fluid media can produce a variety of extracts or products [J.W. King, Sub- and supercritical fluid processing of agrimaterials: extraction, fractionation and reaction modes, in: E. Kiran, P.G. Debenedetti, C.J. Peters (Eds.), Supercritical Fluids: Fundamentals and Applications, Kluwer Publishers, Dordrecht, The Netherlands, 2000, pp. 451–488.] however the modification of processing equipment such as expellers, extruders, and particle production devices extend the use of the critical fluid technology platform. Sequential unit processing using multiple fluids also has been reported although demonstrated to a limited degree—however combining both compressed CO2 and water in a unit process can also impart some unique processing possibilities. The concept of multiple unit and fluid processing supports an environmentally benign or “green” production platform and is consistent with processing sustainable materials. Integration of critical fluids into existing processing concepts such as biomass conversion, biorefineries, and synthesis based on methyl ester intermediates are discussed.The past twenty years has seen an expansion of the “critical fluid” technology platform with respect to using or combining multiple types of unit operations and compressed fluids in both their sub- and supercritical states. Although supercritical fluid extraction (SFE) utilizing supercritical carbon dioxide (SC-CO2) has seen considerable industrial use, the high capitalization cost of building and running such production plants promotes expanding their use and functionality with respect to multi-unit operations and multiple fluids. An evaluation of the current status of implementing such an approach is provided, including systems based on pressurized liquid fluids, and a perspective of future needs in this area are discussed.