بررسي تجربي و مدل سازي رياضي فرآيند استخراج فوق بحراني تاكسيفولين از پوست كاج نيگرا و بهينه سازي شرايط عملياتي با الگوريتم ژنتيك

چكيده انگليسي :

Experimental Investigation and Mathematical Modeling of Supercritical Extraction of Taxifolin from Pine Pinus nigra Bark and Optimization of Operating Condition by Genetic Algorithm Siamak Mohamadi siamak mohamadi@ce iut ac ir Date of submission 21 September 2013 Department of Chemical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Prof Seyyed Mohammad Ghoreishi ghoreshi@cc iut ac ir Abstract The previous investigations showed that pine bark contains flavanolignan and dihydroflavanol compounds that have interesting and important therapeutic activities One of this compounds is taxifolin The bioflavonoid taxifolin is the most promising natural antioxidant The antioxidative activity of taxifolin exceeds that most common antioxidants such as tocopherols vitamin E and carotenoids vitamin A An important advantage of taxifolin is the ability to prevent cancers Taxifolin is also a very important nutrient for blood This Flavonoid improves blood circulation and reduces blood levels of low density lipoprotein LDL cholesterol Extraction of antioxidants from plant with toxic liquid solvents under specific conditions such as high temperature acid and enzyme contact significantly decrease the biological quality of the natural medicinal materials The extraction method must be designed in such a way that extracted compounds do not contact the toxic and carcinogenic solvents In this study it is focused on the experimental production of taxifolin via supercritical fluid extraction method and characterization of the produced toxifolin Extraction experiments were performed using pine bark powder supercritical carbon dioxide and ethanol For separation of taxifolin from pine bark supercritical CO2 extraction was carried out on a laboratory scale under the following operating conditions 40 10 30 MPa 0 4 2 ml min CO2 flow rate 30 150 min extraction dynamic time High performance liquid chromatography HPLC was applied to identify taxifolin in extracted samples In order to obtain maximum taxifolin recovery as the objective function of this research the effective extraction parameters were optimized using response surface methodology The optimum conditions were found to be the extraction dynamic time of 133 03 min 18 48 Mpa 41 01 1 72 ml min to achieve taxifolin recovery of 34 15 Response surface analysis showed that the data were adequately fitted to second order polynomial model R2 and modified R2 of the model are 98 27 and 96 76 respectively A general mathematical model for supercritical CO2 extraction was performed The model was developed utilizing diffusion controlled regime in the pore and film mass transfer resistances with axial dispersion of the mobile phase at dynamic conditions The mass transfer parameters i e effective pore diffusivity film mass transfer coefficient and axial dispersion along with the Henry coefficient were chosen as the model parameters The first three mass transfer parameters were predicted using nondimensional equations from the literature Henry law was used to describe the equilibrium state of solid and pore fluid phases Genetic algorithm was applied to determine the optimal value of Henry coefficient such that to minimize the absolute average deviations between the experimental and predicted extraction recoveries Indicated by obtained results the mathematical model is able to predict the experimental data with acceptable accuracy The main process conditions which must be determined to maximize the extraction recovery are temperature pressure flow rate of CO2 and dynamic extraction time These were optimized by genetic algorithm The optimal operating conditions were observed at 40 C 18 57 MPa 1 98 ml min and 132 21 min There was good agreement between two methods of optimization Supercritical fluid extraction by carbon dioxide as extraction solvent have lots of advantages such as low supercritical temperature and non toxicity Keywords Pine bark Taxifolin Superc

محمدي، سيامك

بررسي تجربي و مدل سازي رياضي فرآيند استخراج فوق بحراني تاكسيفولين از پوست كاج نيگرا و بهينه سازي شرايط عملياتي با الگوريتم ژنتيك

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