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Masoud Rahimi,Peyvand Valeh-e-Sheyda,Hamed Rashidi 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.11
The paper deals with the development and optimization of curcumin nanosuspension by solvent/anti-solvent precipitation method in a microfluidic platform. A three-level Box-Behnken design was applied as an optimizing technique to investigate the effect of three independent operating variables, namely, volume ratios of anti-solvent to solvent, flow rate of drug solution, and curcumin concentration on the preferred response. In presence of PVP as the stabilizer, a nano-curcumin suspension was obtained in the range of 62-335nm. Analysis of variance showed that the variables with the highest effect were the linear effects of the anti-solvent to solvent ratio, and its corresponding squared term. Applying response surface methodology, curcumin nanosuspension with average size of 63.12 nm can be obtained under optimum condition As: S=15, solvent flow rate of 1.0mL/min and curcumin ethanolic concentration of 5.0mg/mL. The prepared nanoparticles were further characterized by infrared spectroscopy, scanning electron microscopy, and X-ray diffraction tests.
Experimental and computational fluid dynamics modeling of mixing by Visco-jet impellers
Masoud Rahimi,Saeideh Amraei,Ammar Abdulaziz Alsairafi 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.6
This paper reports experimental and computational frluid dynamics (CFD) studies on an impeller called Visco-jet with the aim of finding the effect of two side diameters ratio of its blade, which has a semi-conical shape,on drawdown process of floating polymericparticles into high viscosity glycerin solution. Nine different geometries were examined experimentally, and there were significant differences in their performance. The results reveal that when diameter of smaller side of semi-cone impeller is half of the other side, mixing was performed in a more efficient way. The CFD-predicted results have been used for explaining the experimental observation. The CFD-predicted hydrodynamics parameters confirm superiority of this geometry compared with the other ones.
Masoud Rahimi,Mahboubeh Faryadi,Mona Akbari 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.3
This paper reports the effect of 1.7MHz ultrasound wave on decolorization efficiency of Rhodamine B (RB) solution by ozone in a T-type microreactor. Response surface methodology using central composite design (CCD) was used for analysis and optimization of the reaction conditions. The effective parameters such as solution pH, dye initial concentration, liquid volumetric flow rate, ozone dosage and the length of microreactor on decolorization process were investigated. Rhodamine B removal from solution was determined in presence of and without sonication. The results indicate that for both modes, the decolorization efficiency of RB increased with increase of the ozone dosage as well as the length of employed microreactor. However, with increase of RB initial concentration and liquid flow rate, the decolorization efficiency was decreased. The comparison between the reactors with and without sonication shows that the application of ultrasound wave is effective more than 15% on removal efficiency of RB at various conditions. At optimum conditions, the experimental RB removal yield of 97.3% and 95.8 was obtained for with and without irradiation layouts, respectively. The statistical analyses and the agreement of the experimental results with model predictions showed the reliability of the regression model.
Masoud Rahimi,Elham Mohamadian,Soheil Dadari,Mohammad Moein Arbab,Naser Karimi 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.4
Microalgae are considered the biological drug factories of the future. To benefit from these microfactories, the intracellular metabolite of algae should be extracted. One of the most economically competitive methods is the ultrasound technique. This study was concerned with ultrasound-assisted extractions of useful substances from microalgae by comparing direct and indirect irradiation methods with respect to the extraction rate and yields. It is most likely that the direct and indirect irradiations had different irradiation powers. The systems were exposed to ultrasound wave (1.7 MHz) for 240min. For each system, the changes of optical density, concentration and biovolume of Chlorella were estimated. In addition, the concentration of extracted chlorophylls (a, b and a+b), carotenoid and lipid were measured. The factors were studied after 30, 60, 120, 180 and 240 min of exposure to ultrasound irradiation. Both direct and indirect irradiation systems produced cavitation in the cell membrane, and they reduced the concentration and biovolume of the Chlorella cells. The amount of lipids and chlorophylls was greater in the direct irradiation as compared to the indirect one, and it caused more cell disruption. However, the extraction of the carotenoid was less effective because direct irradiation produced more transmitted power of ultrasound, resulting in degradation of carotenoid. The results and analysis presented in this research showed that selection of the best method of irradiation is an important step, and it depends on the biomaterials to be extracted.
Masoud Rahimi,Soheil Dadari,Sirus Zeinaddini,Elham Mohamadian 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.5
Polyethersulfone (PES) nanofiltration (NF) membranes were prepared by blending of synthesized hydrophilic adipate ferroxane nanoparticles (AFNPs) as a novel multifunctional nanofiller via the phase inversion method. The water contact angle measurement indicated the higher hydrophilicity of the NF membranes. The water flux of the membranes improved significantly after the addition of AFNPs, from 10.4 to 32.2 kg/m2h. Antifouling characteristics of AFNPs/PES membranes were improved by increased hydrophilicity and decreased membrane surface roughness. The 0.6 wt% AFNPs/PES membrane exhibited the highest FRR (96%) and the lowest irreversible fouling resistance (6%). The nanofiltration performance of the prepared membranes was evaluated by dye removal and salt retention. The results proved the high dye removal capability of modified membranes (98% rejection) compared with the unfilled PES membrane (89% rejection). The salt retention sequence for membrane with 0.2 wt% of nanoparticles was Na2SO4 (70%)>MgSO4 (60%)>NaCl (18%).
Masoud Rahimi,Aso Kakekhani,Ammar Abdulaziz Alsairafi 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.4
Experimental and computational fluid dynamic (CFD) modeling studies have been performed on mixing characteristics of a new modified helical ribbon impeller in a viscous medium. A novel arrangement for the multiple reference frame (MRF) technique was proposed and the modeling results were compared with those of conventional MRF selecting method. Calculations were performed to study the effects of several parameters: axial flow number,axial circulation time, impeller clearance, and power consumption. The higher performance of the modified impeller has been proven in terms of axial flow number and axial circulation time. The results showed that significant improvement in mixing performance can be obtained at a higher impeller clearance with the modified impeller employed. In addition, the power consumption by the new impeller has been compared with that of the classic one. The CFDpredicted flow patterns generated by the impellers were used to explain the higher performance of the modified impeller. In addition, the results reveal that the CFD-predicted particle volume fractions at various axial distances from the tank bottom are reasonably in agreement with the experimental observations.
Heat transfer and fluid flow modeling in serpentine microtubes using adaptive neuro-fuzzy approach
Masoud Rahimi,Reza Beigzadeh,Marziyeh Hajialyani 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.5
An adaptive neuro-fuzzy inference system (ANFIS) is applied to predict thermal and flow characteristics in serpentine microtubes. Heat transfer rate and pressure drop were experimentally measured for six serpentine microtubes with different geometrical parameters. Thermal and flow characteristics were obtained in various flow conditions. The ANFIS models were trained using the experimental data to predict Nusselt number (Nu) and friction factor (f) in the studied serpentine microtubes as a function of geometric parameters and flow conditions. The model was validated through testing data set, which were not previously introduced to the developed ANFIS. For Nu prediction, the root mean square error (RMSE), mean relative error (MRE), and absolute fraction of variance (R2) between the predicted results and experimental data were found 0.2058, 1.74%, and 0.9987, respectively. The corresponding calculated values for f were 0.0056, 2.98%, and 0.9981, respectively. The prediction accuracy of the ANFIS models was compared with that of corresponding classical power-law correlations and its advantages are illustrated.
CFD modeling of the effect of absorbent size on absorption performance of a packed bed column
Masoud Rahimi,Mohsen Mohseni 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.3
This paper reports a study on the ability of the computational fluid dynamics (CFD) modeling for analyzing the fluid flow hydrodynamics and absorption in a packed bed column. The water absorption by silica gel absorbents in an experimental packed bed was investigated, and the absorption performance of two different sizes of absorbent was studied. A series of experiments were carried out for five setups which are different in the weight ratio of the employed big to small absorbents. The CFD modeling was carried out for all five experimental setups. The predicted results show that by more replacing of the big absorbents with the small ones the water absorption increased. On the other hand, a greater pressure drop was observed as more small absorbents were used. The predicted absorption rates were compared with the measured values and on average a consistency within 11.6% was observed.
Masoud Mandooie,Mahdi Rahimi,Golara Nikravesh,Ehsan Salehi 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.117 No.-
Urea alcoholysis is one of the environmental-friendly and economic methods for dimethyl carbonate(DMC) production. Various catalysts such as bases, organic tin, acids, ionic liquids and metal oxides havebeen used for synthesis of DMC through urea alcoholysis process. Based on literature survey, catalystscontaining both acidic and basic sites, are more suited for catalyzing the reaction; however, the basicityplays more conspicuous role. Zinc-based mixed metal oxides (MMOs) have emerged as potential catalystsfor this purpose mainly due to the amphoteric nature of ZnO as well as basic/acidic sites abundance. Thisarticle reviews zinc-based MMO catalysts focusing on catalytic performances and mechanisms, synthesizingmethods, characterizations and operating conditions of the reactors during a 20-years period. Literature survey uncovered that pure ZnO catalyst could exhibit a maximum of 37% DMC yield underthe utmost operating conditions. However, zinc-based MMO catalysts (binary or ternary) showed superiorperformance in DMC conversion through the urea alcoholysis process, usually under moderate operatingconditions, mainly due to synergetic effects among metal oxide phases. Among MMO catalysts,ZnO/CaO binary metal oxide and Zn/Ce/La ternary metal oxide catalysts tabulated the highest DMC productionyields of 41.2% and 50.4% respectively. Moreover, two different catalyst-test modes includingbatch and continuous, and three catalyst synthesizing methods including sol–gel, co-precipitation andurea precipitation (UPM) have been spotlighted in this review.