Pieck, Carlos Ariel
In this work, the supercritical fractionation of fatty acid ethyl esters derived from fish oil was carried out with carbon dioxide at 333 K and 14.5 MPa. The feed mixture is very complex, with over 80 different compounds detected by GC. Among them, the EicosaPentaenoic Acid (EPA) and DodecaHexaenoic Acid (DHA) ethyl esters are of major industrial interest since the consumption of these omega-3 acids has been linked to a reduced risk of cardiovascular diseases. The influence of the process parameters on the separation efficiency is an important point for an economic analysis of the overall purification process. First, the partition of the feed mixture was determined for different solvent-to-feed ratios varying between 21.8 and 143; the extract yield (i.e. the mass fraction of feed recovered as extract) has been calculated for each condition. Then, a new simplified equilibrium-stage model was developed and applied to the mixture. Supposing a constant distribution ratio, this model is able to correlate the influence of the solvent-to-feed ratio (through a calculated extract yield) on the concentration of the major 24 compounds present either in the feed or in the extract and raffinate, including components with low, medium and high distribution ratios. (C) 2016 Elsevier B.V. All rights reserved.
Di Capua, Alessia
beta-carotene (BC) is one of the best known and used bioactive compounds with antioxidant activity. In this work coprecipitation of BC with polyvinylpyrrolidone (PVP) by Supercritical Assisted Atomization (SAA) has been studied. to enhance BC bioavailability and to provide its protection against oxidation. Two solvents have been used: ethanol and a mixture acetone/ethanol 70/30 (v/v). In both cases SAA produced spherical and amorphous microspheres with d(50) ranging between 0.42 and 0.84 mu m using ethanol, and 0.28 and 0.48 mu m using the solvent mixture. UV-vis analyses revealed a BC content up to 94% and high scavenging activities confirm that PVP is able to protect it from degradation. BC dissolution rate in a phosphate buffered saline solution (PBS) was up to 22 times faster than that of physical mixture. The major difference between coprecipitates was in their dissolution rate: it depended also on the kind solvent used, indicating a possible different internal particles organization during droplet drying. (C) 2019 Published by Elsevier B.V.
Toudji, Sid-Ali Amine
The aim of this work is to show that the equations developed by Sovova, based on the concept of broken and intact cells for describing the supercritical extraction curves from plants and vegetables, can be applied for the modelling of the supercritical CO2 extraction curves obtained with microalgae. Experimental and modelling results of supercritical carbon dioxide extraction of lipids from four different microalgae: Nannochloropsis oculata, Cylindrotheca closterium, Chlorella vulgaris and Spirulina platensis, are presented. The experimental setup is a laboratory scale apparatus which allows an accurate monitoring of the mass loss of the microalgae sample during the extraction. The experimental data were obtained at a pressure of 40 MPa, a temperature of 333 K and CO2 flow rates from 0.3 to 0.5 kg h(-1). The extraction experiments were performed on samples having undergone different pretreatments: (i) after harvesting and centrifugation, microalgae were dried either by freeze-drying or air flow drying) and (ii) they were ground and sieved at different particle sizes (particle diameters ranging from 160 to 1000 pm). The complete extraction of neutral lipids was performed leading to mass losses up to 30% depending on the samples and on the operating conditions. Extracts were mainly composed of triglycerides (more than 90 wt% of extracts). The mathematical model published in 2005 and the simplified equations of extraction curves (using the characteristic times characterizing each extraction step) published in 2012 by Sovova were chosen to fit the experimental data. Among the hypotheses proposed by Sovova, we considered that the flow pattern of supercritical CO2 in the extraction autoclave was plug flow and the extraction process was supposed to occur with negligible solute-matrix interactions. The adjustable parameters were calculated by minimizing the sum of least squares between experimental and calculated values of the extraction yield. Good agreement between the two models and our experimental measurements was obtained. The average absolute relative deviation ranges between 0.5 and 10.2%. (C) 2013 Elsevier B.V. All rights reserved.
This article deals with the extraction of neutral lipids and antioxidants from enriched Spirulina platensis microalgae using supercritical carbon dioxide (CO2), and more particularly with the influence of experimental conditions on extraction yields and kinetics at laboratory and pilot scales. Preliminary studies were carried out at laboratory scale before the establishment of an experimental design: extraction curves were plotted for different autoclave fill rates, and under different conditions of pressure and temperature. Using a Response Surface Methodology, the significant influence of pressure on extraction efficiency was highlighted. Surface responses showed that, in the studied experimental field, mass loss increased when pressure, temperature, and CO2/microalgae mass ratio increased. Extract analyses showed that oil extracts contained chlorophylls a and b, as well as beta-carotene. Finally, larger-scale experiments were carried out with batches of 1 and 50 kg (scale-factors of 100 and 5000, respectively) and the results were consistent with those obtained at laboratory scale. (C) 2016 Elsevier B.V. All rights reserved.
De Nadai, Axel
Garcia Perez, Antonio
The supercritical oil extraction from oleaginous seeds (sunflower and rapeseeds) is presented here through experimental and modelling results. The experimental setup allows an accurate following of the mass of the oil extracted and to derive the experimental influences of pressure, temperature and supercritical CO(2) flowrate on the extraction curves. These parameters are very sensitive and highlight the necessity of precise optimisation of experimental conditions. In order to complete the behaviour of supercritical fluids extraction, an improved modelling is proposed. The modelling basic equations are based on others modelling published previously. In this work, the determination of several parameters comes from correlations and the other constants are fitted with all the experimental results. Thus the modelling is more representative and predictive as other ones. The modelling results present a good agreement with the experimental results, and hence it can be used for the dimensioning of some extraction autoclaves. (C) 2011 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
An experimental design has been built in order to study the influence of different parameters on the oil extraction yield for two types of seeds (rape and sunflower) using supercritical CO(2): pressure (15-45 MPa), temperature (35-75 degrees C), CO(2) flow rate (8-19 kg h(-1)) and extraction duration (20-120 min). Extraction yields are between 0.3% and 89.8%, indicating that the experimental design covers a large range of results. Acidic and phosphorus contents in the oil and protein content in the residual cake have been done. The results indicate that pressure and extraction duration are the most influencing parameters together with temperature in the case of rape seeds. Thermodynamic effects (solubility) and kinetic effects (mass transfer depending on the seeds) have been evidenced. The selectivity of pure supercritical CO(2) has been shown: any phospholipid is extracted. In addition to selectivity, another interest of the process is the purity of the products recovered, totally free from organic solvent. (c) 2008 Elsevier Ltd. All rights reserved.
Oxeglitazar is a new orally administered poorly water soluble active substance used in the treatment of type II diabetes. The objective of this work was to improve its dissolution kinetics using supercritical antisolvent (SAS) and spray-freezing (SF) techniques. Oxeglitazar was formulated with various excipients, including: Poloxamer 188 and 407, polyethylene glycol (PEG) 8000 and polyvinylpyrrolidone (PVP) K17 in a 1:1 weight ratio. In the SAS technology, pharmaceutical ingredients were dissolved in an appropriate solvent, and the feed solution was dispersed through a capillary nozzle in supercritical CO(2) (SC CO(2)). Dichloromethane (DCM), chloroform (CHCl(3)), and a binary co-solvent system of chloroform-ethanol (EtOH/CHCl(3) 50:50, v/v%) were tested. In the SF process, tert-butanol (tBuOH) was used as solvent. The feed solution was injected into liquid nitrogen through a capillary nozzle located above the surface of the boiling nitrogen. Frozen particles were collected and freeze-dried for 30 h. Formulations were compared in terms of particle morphology, particle size, flow properties, crystallinity, polymorphic purity, residual solvent content, precipitation yield, drug content, specific surface area and dissolution kinetics. SAS and SF processed formulations exhibited enhanced dissolution rates. Within 5 min, the amount of dissolved drug varied from 31.6 to 64.3% for SAS and from 77.9 to 96.9% for freeze-dried formulations while only 30.5% was dissolved from raw drug. Apart from oxeglitazar/PVP K17, SAS prepared solid dispersions were characterized by high crystallinity and acicular shape. Freeze-dried formulations consisted of porous spherical particles with high amorphous content (94.2-100%).