| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 231112 | The Journal of Supercritical Fluids | 2012 | 11 Pages |
In this work, enriching of anti-oxidants has been systematically investigated by supercritical adsorption process. The adsorption of buriti oil (Mauritia flexuosa Mart.) has been determined experimentally by the method of frontal analysis in columns packed with γ-alumina at 15, 20, and 25 MPa, 333 K, and solvent flow rate of QCO2=10.6 L/minQCO2=10.6 L/min, using an assemble of coupled columns of 81 cm3, adopted to be used as an adsorption cell. The oil of buriti has been physical–chemically characterized according to AOCS official methods in terms of acid, saponification, peroxide and iodine values, refraction index, density and viscosity. Chemical composition of buriti oil in terms of fatty acid esters has been performed by GC and anti-oxidants activity by the method of free radical capture (DPPH). The adsorbent was characterized by X-ray fluorescence, X-ray powder diffraction, electron scanning microscopy, particle and pore size distribution, particle porosity and specific area. A material balance has been performed on the adsorption column to compute the cumulative mass of adsorbing species in γ-alumina on supercritical adsorption process by applying a pseudo-first order kinetic model as well as an integral kinetic model. The influence of pressure on the supercritical adsorption has been investigated by analyzing the mass transfer performance. A Langmuir type isotherm has been used to model the experimental adsorption data.The results show that adsorbent capacity increases with pressure, showing a maximum of 99.486 mgOil/gγ-alumina at 25 MPa. In addition, the concentration of anti-oxidant shows a tendency to increase during the curse of supercritical adsorption and with increasing system pressure. Fractions rich in anti-oxidants could be obtained at adsorption column outlet, showing a 2.0 fold enriching by 20 MPa and a 6.5 fold enriching by 25 MPa approximately, corroborating to assert this methodology as feasible to concentrate anti-oxidants from buriti oil. The supercritical adsorption of buriti oil fat soluble compounds in γ-alumina using carbon dioxide as solvent may be applied as an alternative method for the enriching of anti-oxidants.
Graphical abstract.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Antioxidants were enriched by supercritical adsorption of Buriti oil in γ-alumina at 333 K, CO2 = 600 l/h, 15, 20, and 25 MPa. ► Buriti oil was characterized by AOCS methods, γ-alumina by XRF, XRD, SEM, particle/pore size distribution, and specific area. ► Mass of adsorbing species on γ-alumina was regressed by kinetic models and the adsorbent capacity by a Langmuir isotherm. ► Adsorbent capacity and concentration of antioxidants increase during the curse of supercritical adsorption with pressure. ► A 6.5 fold enriching was obtained by 25 MPa, asserting this method as feasible to concentrate antioxidants from Buriti oil.
