فهرست مطالب

Chemical Engineering - Volume:13 Issue: 4, Autumn 2016

Iranian journal of chemical engineering
Volume:13 Issue: 4, Autumn 2016

  • تاریخ انتشار: 1395/07/19
  • تعداد عناوین: 7
|
  • A. Soroushnia, F. Ganji*, S. M. Taghizadeh Page 3
    Desmopressin acetate is a potent synthetic peptide hormone that is administered via parenteral, intranasal and oral routes. A more acceptable route of administration with potentially good bioavailability could be offered by transdermal delivery. The present work reports on the development of water-in-oil (w/o) microemulsions for the transdermal administration of desmopressin acetate. A water-in-oil nano/submicron emulsion for transdermal administration of desmopressin was developed. Its skin penetration profiles were determined using Franz-diffusion cell. Pseudo-ternary phase diagrams for emulsion regions were constructed. Effects of hydrophilic-lipophilic balance (HLB), ratio of surfactants and co-surfactant mixture to oil phase (Smix/oil) and ratio of surfactants to co-surfactant (S/Cs) on skin flux were also evaluated.
    Skin flux was increased when S/Cs and Smix/oil were decreased, and HLB was increased. Optimized formulation was obtained as: HLB=8, S/Cs=3 and Smix/oil=5.4, with average particle size of 69 nm. The optimized nano/submicron emulsions increased desmopressin skin flux 4.45 fold relative to drug solution. Skin flux was increased when S/Cs and Smix/oil were decreased, and HLB was increased. Optimized formulation was obtained as: HLB=8, S/Cs=3 and Smix/oil=5.4, with average particle size of 69 nm. The optimized nano/submicron emulsions increased desmopressin skin flux 4.45 fold relative to drug solution.
    Keywords: Desmopressin, Nano, Submicron Emulsion, Transdermal, Statistical Evaluation, Optimization
  • M. Pirdashti*, K. Movagharnejad, S. Curteanu, F. Leon, F. Rahimpour Page 14
    Guanidine hydrochloride has been widely used in the initial recovery steps of active protein from the inclusion bodies in aqueous two-phase system (ATPS). Knowledge of the guanidine hydrochloride effect on the liquid-liquid equilibrium (LLE) phase diagram behavior is still inadequate and no comprehensive theory exists for the prediction of the experimental trends. Therefore, the effect of the guanidine hydrochloride on the phase behavior of PEG4000ꚋ媲좮 phosphate water system at different guanidine hydrochloride concentrations and pH was investigated in this study. To fill the theoretical gaps, the typical support vector machines were applied was applied to the k-nearest neighbor method in order to develop a regression model to predict the LLE equilibrium of guanidine hydrochloride in the above mentioned system. Its advantage is its simplicity and good performance, with the disadvantage of an increase in the execution time. The results of our method are quite promising; they were clearly better than those obtained by well-established methods such as Support Vector Machines, k-Nearest Neighbor and Random Forest. It is shown that the obtained results are more adequate than those provided by other common machine learning algorithms.
    Keywords: Liquid, Liquid Equilibrium, Aqueous Two Phase System, Nearest Neighbor, Large Margin, Regression Analysis
  • R. Rahimi*, Sh. Boulaqhi, E. Ziarifar Page 33
    Simulation of a process and analysis of its resulting data in both dynamic and steady-state conditions are fundamental steps in understanding the process in order to design an efficient system control, as well as implementing operational cost reduction scheme. In the present paper, steady and unsteady state simulation of Amir Kabir1,3 butadiene purification units has been done by using Aspen and Aspen Dynamic software together with the Peng- Robinson equation of state to investigate the system responses to the disturbances.
    In the unsteady state simulation mode the flow rates, pressure, temperature and level (FPTL) were controlled by Proportional-Integral-Derivative (PID) controllers in the unit. Finally, transient responses to changes such as feed temperature, feed flow rates, steam flow rates and the duties of the re-boiler of columns in unit were gained. For reaching purified 1,3 butadiene, sensitivity of the process to the fluctuations of feed temperature and on the duties of the re-boilers of the columns is noticeable.
    Keywords: Simulation, Steady, State, Dynamic, Distillation, PID
  • H. Hadi Najafabadi, M. Keshavarz Moraveji* Page 46
    In this paper, three-dimensional incompressible laminar fluid flow in a rectangular microchannel heat sink (MCHS) using Al2O3/water nanofluid as a cooling fluid is numerically studied. CFD prediction of fluid flow and forced convection heat transfer properties of nanofluid using single-phase and two-phase model (Eulerian-Eulerian approach) are compared. Hydraulic and thermal performance of microchannels are investigated according to the results of the friction factor, pumping power, average heat transfer coefficient, thermal resistance, average temperature of the walls and entropy generation. In addition, due to the CFD results, two correlations for prediction of Nusselt number and friction factor are presented. Comparing the predicted Nusselt number using single-phase and two-phase models with experimental data shows that the two-phase model is more accurate than single-phase model. The results show that increasing the volume fraction of nanoparticles leads to increases in the heat transfer coefficient and reduces the heat sink wall temperature, but it results in the undesirable effect of increase in pumping power and total entropy generation.
    Keywords: Nanofluid, Microchannel, Convective Heat Transfer, Friction Factor, Entropy Generation, CFD
  • R. Faridvand, S. J. Peighambardoust*, A. Shenavar Page 62
    In this study, in-situ bulk polymerization was investigated for obtaining flame retardant polystyrene (PS). The halogenated and phosphoric compounds were used as flame retardant additives and Perkadox 30 was used as a synergist. The flammability of the PS was evaluated by thermogravimetric analyzer (TGA), limiting oxygen index (LOI) and UL-94 tests. The results show that polymerization process for production of flame retardant polystyrene requires lower amount of flame retardant additives compared with the process for production of flame retardant composites. Furthermore, using Perkadox 30 as a synergist lowers the loading of flame retardant additives. LOI tests show that flame retardant polystyrene is synthesized by adding at least 0.35 % (w/w) hexabromocyclododecane (HBCD) during polymerization. TGA analysis confirms that with addition of HBCD the degradation temperature decreases and weight loss occurs quickly. The degradation temperature of the sample consisting of 0.8 % (w/w) HBCD was lower than the sample that consists of 0.35 % (w/w) HBCD and 0.45 % (w/w) triphenylphosphate (TPP). The pure polystyrene did not pass the UL-94 test because of inflammability and greater dripping. For samples with HBCD, less time is needed to quench the flame and these samples passed the UL-94 test. On the other hand, greater dripping of polymer melt led to transmission of UL-94 rate from V0 to V2. It is also observed that flaming rate for samples with TPP was very low and dripping did not occur.
    Keywords: Styrene Monomer, In, Situ Bulk Polymerization, Flame Retardant, Thermal Properties
  • M. Heravi, M. Bayat *, M. R. Rahimpour Page 71
    The main focus of this study is improvement of the steam-methane reforming (SMR) process by in-situ CO2 removal to produce high hydrogen content synthesis gas. Sorption enhanced (SE) concept is applied to improve process performance. In the proposed structure, the solid phase CO2 adsorbents and pre-reformed gas stream are introduced to a gas-flowing solids-fixed bed reactor (GFSFBR). One dimensional mathematical model is developed to evaluate the effect of adsorbents on the efficiency of SMR at steady- state condition. To prove the accuracy of the considered model, simulation results are compared against available industrial plant data. Modeling results illustrate that application of SE method in SMR enhances syngas production and reduces CO2 content. The reported data indicate that by overcoming thermodynamic limitations and controlling coke formation, CH4 conversion and H2 yield improve about 23 % and 29 %, respectively. For more investigation, sensitivity analyses of some related parameters of the pre-reformed gas are performed to predict optimum conditions. Finally, the proposed GFSFBR for the SMR process leads to higher hydrogen production and H2/CO ratio. As the last part, non-dominated sorting genetic algorithm-II is applied to perform multi-objective optimization of the SE-SMR.
    Keywords: Hydrogen Production, Steam, Methane Reforming, Sorption, Enhanced Reaction, CO2 Adsorption, Multi, objective Optimization
  • L. Omidvar Langroudi, H. Pahlavanzadeh*, S. Nanvakenari Page 96
    The current research aims at conducting an experimental and theoretical investigation on the performance of air dehumidification system using a nanofluid of γ-alumina nano-particles in LiBr/H2O, as a desiccant. Comparative experiments organized using a central composite design are carried out to evaluate the effects of six numerical indices (air velocity, desiccant flow rate, air humidity ratio, desiccant solution concentration, air temperature, desiccant temperature) and one categorical factor (adding nano-particles), on outlet air humidity ratio and outlet air temperature as responses. Reduced quadratic regression models are derived for each response. The obtained results revealed that LiBr/H2O solution concentration and air temperature have the most significant effect on outlet air humidity ratio and outlet air temperature, respectively. It was found that the average rates of mass transfer and heat transfer increased to 12.23 % and 13.22 %, respectively, when γ-alumina nano-particles (0.02 wt %) were added to the LiBr/H2O solution. The average rates of mass and heat transfer coefficients increased to 22.73 % and 26.51 %, respectively.
    Keywords: Liquid Desiccant, Dehumidification, RSM, Nano, Particles, Mass Transfer, Heat Transfer