M. Rahmanzadeh derisi; N. Esfandiari
Abstract
The gas antisolvent (GAS) process has been employed for pharmaceutical micronization. Ampicillin was dissolved in organic solvent and carbon dioxide as an antisolvent was injected into this solution, consequently, volume expansion and sharp reduction in liquid solvent power were shown. The particles ...
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The gas antisolvent (GAS) process has been employed for pharmaceutical micronization. Ampicillin was dissolved in organic solvent and carbon dioxide as an antisolvent was injected into this solution, consequently, volume expansion and sharp reduction in liquid solvent power were shown. The particles in GAS process are not seen in any operating conditions. Thermodynamic modeling of GAS can evaluate the operating conditions. In this project, the effect of solvent on optimal thermodynamic conditions of the binary system (CO2, solvent) and ternary system (CO2, solvent, ampicillin) were investigated. The relative change in molar volume in different solvent (ethanol, 1-propanol, 1-butanol, and 1-pentanol) was studied for determination of the optimum operating conditions. The combination of Peng-Robinson EOS and Vidal and Michelsen mixing rule (LCVM) was selected to determine the optimum operating condition of the GAS process. The effect of solvent on minimum pressure was investigated. The calculated Pmin was 70, 70.86, 72.2 and 73.4 bar for ethanol, 1-propanol, 1-butanol, and 1-pantanol at, 308.15 K respectively. According to modeling results, when the molecular weight of the solvent was increased, the value of Pmin was increased.
Process Control and Engineering, Process Safety, HSE
V. zaroushani; H. mirzakhani; F. khajehnasiri
Abstract
Natural gas (NG) is one of the cleanest and safest sources of energy transmitted in a high pressure that must be reduced before entering City Gas Station (CGS). Identifying the effective parameters in creating the hazardous areas of CGS is essential to crisis and management. This study using PHAST version ...
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Natural gas (NG) is one of the cleanest and safest sources of energy transmitted in a high pressure that must be reduced before entering City Gas Station (CGS). Identifying the effective parameters in creating the hazardous areas of CGS is essential to crisis and management. This study using PHAST version 7.11(created by DNV Company) conducted a consequence modelling in three scenarios at three CGS stations in Qazvin Province, by actual data including weather conditions, gas pressure and temperature. The main results for the modeling in all three scenarios were jet fire, flash fire, and explosion. Based on the modeling results, most flame length was obtained in Avaj station with 10 meters more than others. Most radiation levels were also in Avaj station in about 150 m downwind distance, which can be caused by the longer flame length in this station.The results showed that in fire jet modeling, an increase in air temperature can lead to an increase in gas pressure and temperature, which in this study increased the flame length of 2 to 3 meters. However, the flame length and the hazardous area was higher during the day and summer. The use of PHAST modeling software can provide useful information including high-risk operational area, hazard area, high-risk time period (day, night and season) for the management team to respond to emergency situations in process industries. In addition, it is necessary to consider the combination of different operating parameters such as gas pressure and gas temperature with different weather conditions.
Modeling and Simulation
A. Das; N. Azimi
Abstract
This research presents the performance of bladeless wind turbines. It also familiarizes readers with the phenomenon of eddy current, which serves as the foundation for bladeless turbines. In this direction, these kinds of bladeless turbines have been designed, modeled, and simulated. Firstly, a two-dimensional ...
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This research presents the performance of bladeless wind turbines. It also familiarizes readers with the phenomenon of eddy current, which serves as the foundation for bladeless turbines. In this direction, these kinds of bladeless turbines have been designed, modeled, and simulated. Firstly, a two-dimensional vibrational movement of the cylinder with a natural frequency of 2 Hz was modeled at Re = 51000. Additionally, it was noted that the values of the displacement amplitude, and lift coefficient are -0.1-0.1, and -1.5-1.5 respectively. After that, using 2D simulation, the impacts of two different geometries, horizontal and vertical ellipsoids, on displacement amplitude are examined. Investigations were conducted on important factors such as lift coefficients and displacement amplitude, as well as the vortex flow pattern formed behind these shapes. It was discovered that the vertical ellipsoid shape had the maximum values for the height of the displacement amplitude, and lift coefficient. The most important factor influencing the performance of this type of geometry was examined, namely the dimensionless Reynolds number, which ranges from 15000 to 90000. It was determined that the intended geometry exhibited a larger displacement response as the Reynolds number increased.
N. Mirhoseini renani; N. Etesami
Abstract
The electrohydrodynamic (EHD) drying of Poly (vinyl acetate) latex films was experimentally investigated in a wind tunnel. The influence of various conditions such as the air temperature, air velocity, and concentration of the latex solution, in the presence and the absence of a high electric field, ...
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The electrohydrodynamic (EHD) drying of Poly (vinyl acetate) latex films was experimentally investigated in a wind tunnel. The influence of various conditions such as the air temperature, air velocity, and concentration of the latex solution, in the presence and the absence of a high electric field, was investigated. The effects of the applied voltage intensity, electrode gap, number of needle electrodes, and polarity of corona on the drying rate of polymer films were studies. The drying behavior of films in a wind tunnel was observed by the weighting method and analyzed based on the heat and mass transfer. Results showed the importance of the EHD role in the drying rate of the polymer film. Increasing the intensity of the electric field, number, and configuration of needle electrodes, and decreasing the electrode gap lead to a significant enhancement of the drying rate of the polymer film. Scanning electron microscope (SEM) images were used to analyze the effect of EHD on the morphology of dried films.
Materials synthesize and production
S. Asadi; M. R. Vahdani; R. Mardani
Abstract
In this study, carbon nanotubes were fully aligned by chemical vapor deposition at atmospheric pressure on a silicon substrate at two carbon source flow rates of 28 and 38 sccm (standard cubic centimeter per minute). Acetylene gas (C2H2) as the carbon source for argon gas (Ar) as the carrier gas for ...
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In this study, carbon nanotubes were fully aligned by chemical vapor deposition at atmospheric pressure on a silicon substrate at two carbon source flow rates of 28 and 38 sccm (standard cubic centimeter per minute). Acetylene gas (C2H2) as the carbon source for argon gas (Ar) as the carrier gas for hydrogen gas (H2) for the recovery of the nanoparticle and iron nanoparticles as the catalytic source at 800 °C were used for the growth of the carbon nanotube array. The reaction was carried out in a 48 cm long quartz tube and the gases were injected with specified flow rates. The silicon substrate was coated by the magnetic sputtering method with catalytic iron nanoparticles with a thickness in the range of 3-6 nm. The results of the FESEM analysis showed, as the carbon source flow rate was increased to 38 sccm, the average diameter of the grown carbon nanotubes is increased, and the carbon nanotubes with a diameter of 60-70 nm were most abundant.
Reaction Engineering, Kinetics and Catalysts,
A. Irankhah; Y. Davoodbeygi
Abstract
One of the effective catalysts for hydrogen purification and production via medium temperature shift reaction, is Cu-Ce solid solution. Cu0.1Ce0,9O1.9 was produced using co-precipitation method and then was utilized as support for 5Cu/Ce0.9Cu0.1O1.9 catalyst which was synthesized employing wet impregnation ...
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One of the effective catalysts for hydrogen purification and production via medium temperature shift reaction, is Cu-Ce solid solution. Cu0.1Ce0,9O1.9 was produced using co-precipitation method and then was utilized as support for 5Cu/Ce0.9Cu0.1O1.9 catalyst which was synthesized employing wet impregnation method. X-ray diffraction (XRD) analysis showed that crystalline sizes of Ce0.9Cu0.1O1.9 and 5Cu/Cu0.1Ce0,9O1.9 were 9.22 and 18.33 nm, respectively. The Catalysts were evaluated in medium temperature shift reaction at 300-390 °C and at gas hourly space velocities (GHSV) of 12000 and 30000 h-1, in a fixed bed reactor. Due to higher concentration of Cu and synergic positive effects of both active metal and support, 5Cu/Cu0.1Ce0,9O1.9 catalyst showed better performance. It was also concluded that, because of low residence time at high levels of GHSV, increasing GHSV leads to decrease CO conversion. Then 5Cu/Cu0.1Ce0,9O1.9 was evaluated in microchennel reactor in 2 GHSVs of 12000 and 30000 h-1 and results were compared with the fixed-bed reactor. It can be concluded that microchannel reactor is better in higher GHSVs (lower residence time of gas flow). A microchannel reactor provides a high surface-to-volume ratio and gases pass over the thin layer of catalyst on the coated plates. Hence, due to the better access to the catalytic bed, the reactants react even in a short time, which improves the microchannel performance compared to the fixed bed reactor
H. Faraji; A.R. Habibi; E. Jalilnejad
Abstract
In this study, hydrodynamic characteristics such as gas holdup (ε), liquid phase velocity, and mass transfer coefficient (kLa) for air-diesel system were modeled for bubble column (BCR), airlift (ALR), and airlift with the net draft tube (ALR-NDT) reactors at different superficial gas velocities ...
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In this study, hydrodynamic characteristics such as gas holdup (ε), liquid phase velocity, and mass transfer coefficient (kLa) for air-diesel system were modeled for bubble column (BCR), airlift (ALR), and airlift with the net draft tube (ALR-NDT) reactors at different superficial gas velocities ranging from 0.008 to 0.085 m s-1. A 3D two-fluid Eulerian-Eulerian model was developed using computational fluid dynamic (CFD) technique to model the three configurations of column reactors and predict the hydrodynamic parameters. The results of 3D-CFD modeling showed a good agreement with the experimental data where average error was less than 14 and 9% for ε and kLa, respectively. Although the vortex occurred in BCR and ALR at high gas velocities, however optimum liquid and gas circulation and distribution observed in ALR-NDT. Furthermore, the formation of dead zone (kLa = 0) in the reactors was studied, and the results revealed that ALR-NDT has a lower volume of dead zones (about 8%) in comparison with BCR and ALR. In order to reduce the dead zone in BCR and ALR systems, the location of gas diffuser and draft tube were investigated. The dead zone was decreased by 12% with shifting of gas diffuser to the bottom of the BCR. Also, by increasing the distance of gas diffuser from draft tube, the dead zone was decreased by 40% specifically near the walls of ALR. Meanwhile, the simultaneous shifting of gas diffuser and draft tube to lower position in ALR had no effect on dead zone formation and its distribution.
Materials synthesize and production
Y. Rabbani,; M. Shariaty-Niassar; S.A Seyyedebrahimi
Abstract
Many industries produce large volumes of effluent which are made of oil and its derivatives; very common pollutants in the environment. The use of hydrophobic magnetic particles due to their low cost, low toxicity, and availability is one of the preferred methods for separating oil from water in oil ...
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Many industries produce large volumes of effluent which are made of oil and its derivatives; very common pollutants in the environment. The use of hydrophobic magnetic particles due to their low cost, low toxicity, and availability is one of the preferred methods for separating oil from water in oil spillage issues. This research aims at evaluating the effects of dopamine as a link in the hydrophobicity of carbonyl iron (CI) particles with stearic acid. In this connection, CI @ stearic acid and CI @ dopamine @ stearic acid have been synthesized. The FESEM analysis was used to observe the surface modification and structure of the particles. The magnetic properties of hydrophobic particles were also measured and the magnetic saturation of CI, CI @ stearic acid, and CI @ dopamine @ stearic acid were 200, 169, 131 emu/g respectively. Finally, the contact angle and adsorption capacity of two modified particles were measured. Based on the result, the static contact angles of water drops placed on the beds of the CI, CI @ stearic acid, and CI @ dopamine @ stearic acid were found to be 0°, 162.9°, and 168.24° respectively. The adsorption capacity range for CI@ stearic acid particles was 1.5 to 2.2 and for CI@ dopamine@ stearic acid particles was 1.8 to 3.2. Therefore, the result showed that dopamine had a good effect as a link to the hydrophobicity of carbonyl iron particles.
Reaction Engineering, Kinetics and Catalysts,
Mahdi Hefzi Lotfabadi; Mahdieh Abolhasani
Abstract
The Micromixing plays a key role in the most of industrial processes; enhancing its efficiency is a very important issue. In this study, a typical rotating packed bed (RPB) reactor equipped with the blade packing and high frequency ultrasonic transducers were designed to study the micromixing efficiency ...
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The Micromixing plays a key role in the most of industrial processes; enhancing its efficiency is a very important issue. In this study, a typical rotating packed bed (RPB) reactor equipped with the blade packing and high frequency ultrasonic transducers were designed to study the micromixing efficiency using the iodide/iodate reaction. The utilized ultrasonic transducers were ultrasonic atomizer humidifiers with the frequency of 1.7 MHz. Taking advantage of both the controllable high gravitational force and induced effects of the high frequency ultrasound, simultaneously, in a small volume reactor is the novelty of the present work. The effects of different parameters like the rotational speed, volumetric ratio, concentration of acid, ultrasonic power and number of activ transducers were investigated with and without the ultrasonic field. By increasing the rotational speed and volumetric flow, the segregation index decreased and by increasing the concentration of acid and volumetric ratio, the segregation index increased. In all of experiments, the segregation index decreased significantly under the ultrasonic field. Moreover, by increasing the ultrasonic power and number of active transducers the segregation index decreased. The obtained results indicated that the relative segregation index increased up to 41.1 % under the 1.7 MHz ultrasonic field. Therefore, the high frequency ultrasonic waves can intensify micromixing, even in a high efficiency equipment like RPB
Environmental Engineering,
A.H. Oudi; R. Golhosseini
Abstract
Optimization of the homogeneous rhodium-catalyzed methanol carbonylation reactor to reduce CO2 emissions is studied in this line of research. In this paper, the steady-state homogeneous rhodium-catalyzed methanol carbonylation reactor is simulated using Aspen HysysV.9 software, by comparing the simulation ...
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Optimization of the homogeneous rhodium-catalyzed methanol carbonylation reactor to reduce CO2 emissions is studied in this line of research. In this paper, the steady-state homogeneous rhodium-catalyzed methanol carbonylation reactor is simulated using Aspen HysysV.9 software, by comparing the simulation results with industrial information, a mean relative error (excluding methanol) of 4.8% was obtained, which indicates the high accuracy of the simulation. The central composite design (CCD) and genetic algorithm (GA) with the aid of a simplified process simulation were used to estimate the effect of individual variables (liquid level, the temperature of the catalyst-rich recycle stream, the mole ratio of CO to methanol (MeOH) in the feed, and flow rate of dilute acid stream) and their mutual interactions to reduce CO2 emissions. It is obtained that the liquid level percentage of 46%, the catalyst-rich recycle stream temperature of 120 °C, CO: MeOH molar ratio equal to 1.13:1, and the dilute acid flow rate of 513.14 kmol/hr lead to CO2 reduction by 34%.
Materials synthesize and production
M.A. Zarei; D. Fallah; M. M. Bahri rasht Abadi; M. Mahyari; F. Khori Amirabadi; M. Piryaee
Abstract
1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) is one of the most powerful explosives of which the purity may have a significant effect on increasing the performance of rocket engines. In this research, the synthesis of high purity HMX is presented using the nitration of 1,5-diacetyl-3,7-dinitrooctahydro-1,3,5,7-tetrazocine ...
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1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX) is one of the most powerful explosives of which the purity may have a significant effect on increasing the performance of rocket engines. In this research, the synthesis of high purity HMX is presented using the nitration of 1,5-diacetyl-3,7-dinitrooctahydro-1,3,5,7-tetrazocine (DADN) with a mixture of nitric acid and polyphosphoric acid. The nitration parameters including temperature, time, and the concentration of nitric acid, and polyphosphoric acid were optimized for the desirable purity and efficiency using the response surface method and central composite method (CCD). Based on the optimization, HMX was obtained with a purity of 99% and an efficiency of 92.9% at a temperature of 70°C and the time duration of 70 minutes with a molar ratio of polyphosphoric acid to nitric acid of 1:1:6.
Process Control and Engineering, Process Safety, HSE
H. Bagheri; M. M Khalilipour; J. Sadeghi
Abstract
During the regeneration-coupling process, a novel, plantwide control framework for the diethyl oxalate production unit is provided in this article. This study's benefit is that it uses process improvements that do not possess the intricacy and expense of the two prior structures described by Zhu and ...
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During the regeneration-coupling process, a novel, plantwide control framework for the diethyl oxalate production unit is provided in this article. This study's benefit is that it uses process improvements that do not possess the intricacy and expense of the two prior structures described by Zhu and Luyben. The development of a plantwide control structure for this process was completed in two stages. The efficiency of the process was initially evaluated using a straightforward structure, with the primary goal being to prevent the usage of concentration controllers and complex cascading mechanisms to the greatest extent feasible. Due to the presence of persistent variations in the process effluents in the original structure, it was determined that there were numerous disruptions present that influenced the response during both recycle streams in the process and created variations. During the second phase, using trial and error to implement a functional adjustment in the process, the minimum amount of recycle stream during which the variations were fully removed was separated from the process, and a novel feeding stream was inserted. Following implementing these modifications, it was discovered that the effluent variations of the process are fully removed with just two concentration controllers, and this structure demonstrates instantaneous plantwide control over receiving disturbances.
N. Sadeghi; O. Bakhtiari
Abstract
New promising generations of mixed matrix membranes (MMMs), which potentially have better separation performances than the neat polymeric membranes, are prepared by the incorporation of proper filler particles within polymeric matrices. However, some undesired phenomena like the void formation around ...
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New promising generations of mixed matrix membranes (MMMs), which potentially have better separation performances than the neat polymeric membranes, are prepared by the incorporation of proper filler particles within polymeric matrices. However, some undesired phenomena like the void formation around the filler particles limit this potential improvement. Having proper models is necessary to elucidate the impacts of this phenomenon on the MMMs’ separation performance. Different models have been developed but they are not able to predict the impact(s) of formed voids truly and their predicted void permeabilities are usually overestimated. In this study, the new parameter of the modified filler volume fraction considering the MMM swollen structure due to the formed voids around the filler particles, is employed along with the formed voids’ permeabilities correction factor, as ß, to modify the Maxwell, Bruggeman and Pal models for the MMMs’ permeability prediction. Absolute average relative errors (AAREs) of the modified models predicted that MMMs’ permeabilities or selectivities were considerably reduced to 3.16, 29.92, and 21.95 % from those of the Maxwell, Bruggeman, and Pal models as 31.33, 310.64, and 67.10 % respectively. Additionally, the optimum thicknesses of the formed voids around the filler particles rationally agree with the Knudsen flow concepts.
E. Tohfegar; J.S. Moghaddas; E. Sharifzadeh; S. Esmaeilzadeh-Dilmaghani
Abstract
In this work, hydrophobic silica aerogels were synthesized using sol-gel method and drying at ambient pressure. The surface morphology, pore size, and the presence of functional groups on the surface of the nanoparticles were analyzed using FE-SEM, TGA, FT-IR, and EDX, respectively. After calcination ...
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In this work, hydrophobic silica aerogels were synthesized using sol-gel method and drying at ambient pressure. The surface morphology, pore size, and the presence of functional groups on the surface of the nanoparticles were analyzed using FE-SEM, TGA, FT-IR, and EDX, respectively. After calcination at 500 °C, the hydrophilic property of the adsorbents was evaluated by water contact angle measurements. The calcinated silica aerogels were used for adsorption of nitrate from aqueous solution in both batch and continuous processes. In the batch process, the effect of initial nitrate concentration, contact time, pH level, and adsorbent dosage were investigated. Results showed that the nitrate removal percentage increased with the decrement of the pH level and the initial nitrate concentration. On the other hand, increasing the contact time and the adsorbent dosage resulted in higher removal percentage. Accordingly, process optimization resulted in a nitrate removal of 92.2 %. Furthermore, it was found that the equilibrium results were in agreement with the Langmuir isotherm model better than with the Freundlich model and also the adsorption kinetics followed the pseudo-second-order model. In the continuous process, the effects of the input flow rate, the bed height, and the initial nitrate concentration were investigated.
Environmental Engineering,
M. Ghanbarnezhad; A. Parvareh; M. Moraveji; S. Jorfi
Abstract
The Fe3O4/MW-CNT composite was prepared for a hybrid photo-catalyst-assisted electrochemical process for the removal of BTX contamination from wastewater. Oxidation of multi-walled carbon nanotube was conducted by different treatments including acid treatment and hydrogen peroxide. The XRD, FTIR, SEM, ...
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The Fe3O4/MW-CNT composite was prepared for a hybrid photo-catalyst-assisted electrochemical process for the removal of BTX contamination from wastewater. Oxidation of multi-walled carbon nanotube was conducted by different treatments including acid treatment and hydrogen peroxide. The XRD, FTIR, SEM, TEM, and BET analyses were performed to characterize both the MW-CNT and the synthesized composite. Simultaneous photo-catalyst and electrochemical processes were conducted to evaluate the performance of a new hybrid process for wastewater treatment. The effect of current density, photo-catalyst loading, and BTX initial concentration was investigated experimentally. The characterization results of the synthesized composite show that a mixture of strong nitric acid and sulfuric acid treatment at a high exposure time and low temperature is the best route for MW-CNT oxidation. The removal efficiency of BTX compounds from wastewater using the hybrid photo-electrochemical process was found to be in the range of 28 to 43% for different conditions. The optimum condition for maximum removal of BTX was found by mathematical modeling of experimental data. The results indicate that a combination of photo-catalyst and the electrochemical process can enhance the BTX removal efficiency.
Biomedical and Biotechnology,
F. Amiri; A. R. Habibi; M. M. Nourouzpour
Abstract
The application of the agro-industrial waste as the feedstock helps to decrease the operational cost of the fermentation process. Soapstock is a by-product of the vegetable oil refinery and enriched with fatty acids including linoleic acid which has a high potential application in the production of biosurfactants. ...
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The application of the agro-industrial waste as the feedstock helps to decrease the operational cost of the fermentation process. Soapstock is a by-product of the vegetable oil refinery and enriched with fatty acids including linoleic acid which has a high potential application in the production of biosurfactants. In this study, a dual carbon source system, including glucose and free fatty acids recovered from a sunflower soapstock, was used for the synthesis of sophorolipid (SL) by Candida catenulata. The production of SL showed a major dependence on the initial carbon sources and the concentration of urea as the nitrogen source. The inoculum size was another influential factor in the fermentation process. The optimization of these factors was evaluated by the one-factor-at-a-time and the response surface methodology (RSM). The one-factor-at-a-time approach gained the best SL productivity (Y1) of about 52.08 mg L-1 h-1 and SL-to-biomass yield (Y2) of 712 mgSL gcell-1 at the inoculum size of 4% vv-1, 100 g L-1 of glucose, 80 g L-1 of soapstock, and 7.5 g L-1 of urea. While the RSM, due to considering interactional effects of the factors, obtained the best condition at 100 g L-1 of glucose, 100 g L-1 of the soapstock, 9.3 g L-1 of urea, and an inoculum size of 6.3% vv-1 with the Y1 and Y1 values of about 58.10 mg L-1 h-1 and 713 mgSL gcell-1, respectively. The characterization of the produced SLs by the GC-MS analysis indicated that a di-acylated C16:1 acidic sophorolipid with an m/z ratio of 679 amu was the main product.
Thermodynamics,
ُS.Saba Ashrafmansouri
Abstract
Considering the high number of ionic liquids (ILs) and impracticability of laboratory measurements for all ILs’ properties, applying theoretical methods to predict the properties of this large family can be very helpful. In the present research, ILs’ thermophysical properties are predicted ...
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Considering the high number of ionic liquids (ILs) and impracticability of laboratory measurements for all ILs’ properties, applying theoretical methods to predict the properties of this large family can be very helpful. In the present research, ILs’ thermophysical properties are predicted by a combination of statistical associating fluid theory and group contribution concept (SAFT-γ GC EoS). The studied ionic liquids are 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([emim][CF3SO3]), 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([bmim][CF3SO3]), 1,3-dimethylimidazolium methylsulfate ([mmim][MeSO4]), 1-ethyl-3-methylimidazolium methylsulfate ([emim][MeSO4]), 1-butyl-3-methylimidazolium methylsulfate ([bmim][MeSO4]), 1-ethyl-3-methylimidazolium methanesulfonate ([emim][MeSO3]) and 1-ethyl-3-methylimidazolium ethylsulfate ([emim][EtSO4]). The thermophysical properties including coefficient of thermal expansion, coefficient of thermal pressure, coefficient of isentropic compressibility, coefficient of isothermal compressibility, speed of sound, isochoric and isobaric heat capacities are estimated within broad ranges of pressure and temperature (0.1-60 MPa and 273-413 K). The comparison among the SAFT-γ predictions and some available experimental data show good ability of SAFT-γ EoS to estimate the ILs’ second-order derivative thermophysical properties.
Separation Technology,
M. Abdollahi; A.R. Sadri; Sh. Fatemi; M. Fakhroleslam
Abstract
Vacuum swing adsorption (VSA) for CO2 capture has been a focus of significant research efforts aimed at developing innovative CO2 adsorbent materials. In this study, three adsorbents (MAF-66, AC, and CMS) were utilized for capturing CO2 from flue gas through the VSA process, and their performances were ...
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Vacuum swing adsorption (VSA) for CO2 capture has been a focus of significant research efforts aimed at developing innovative CO2 adsorbent materials. In this study, three adsorbents (MAF-66, AC, and CMS) were utilized for capturing CO2 from flue gas through the VSA process, and their performances were compared. The adsorption equilibrium and kinetics data were gathered from recent literature. A four-step VSA cycle was employed to assess the adsorbents' performance for CO2 capture, with a molar feed composition of CO2:N2 at 15:85%. Simulations of two-colums VSA lab-scales with different adsorbents were conducted. The operating conditions such as total feed flowrate, feed composition, feed pressure, temperature, and vacuum pressure were kept constant, and the impact of the adsorbent mass on recovery and productivity was analyzed. The simulation results indicated that both recovery and productivity decreased with increasing adsorbent mass. Furthermore, the necessary amount of each adsorbent to achieve a purity of 99.5% was determined. The modeling outcomes suggested that the VSA process employing MAF-66, CMS, and AC adsorbents would require 1.25, 3.19, and 8.2 grams of the adsorbent, respectively, to achieve N2 purity of 99.5%. Taking into account parameters such as recovery, productivity, and energy consumption, MAF-66 emerged as the most effective adsorbent in this study.
Environmental Engineering,
A. Hemmati; M. Raeisi; M. borghei
Abstract
Many communities in the world use groundwater as a source of potable water. The high nitrate concentration is a serious problem in groundwater usage. This study utilizes a biological denitrification method to investigate a moving bed biofilm reactor (MBBR) for the case of Tehran's groundwater. One pilot-scale ...
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Many communities in the world use groundwater as a source of potable water. The high nitrate concentration is a serious problem in groundwater usage. This study utilizes a biological denitrification method to investigate a moving bed biofilm reactor (MBBR) for the case of Tehran's groundwater. One pilot-scale MBBR with a 3 liter volume was designed and used in this research. The denitrification reactor operates under anoxic conditions. Methanol was used as a carbon source in the reactor throughout the study, and fifty percent of the reactor volume was occupied with KMT packing (k1). To determine the optimum nitrate loading rate, the concentration of nitrate changed from 100 to 400 mg N/l. It was concluded that heterotrophic denitrifying bacteria converted nitrate to nitrogen. According to obtained results, the removal efficiency and optimum loading rate were estimated during the experiments in different concentrations and different HRTs for this type of reactor. Sodium nitrate was in the feed source in the anoxic reactor. The maximum removal rate of nitrate was measured to be 2.8 g of NO3-N m-2 carrier d-1. Therefore, it was shown that the optimum loading rate of nitrate and the optimum COD/N were equal to 3.2 g of NO3-N m-2 carrier d-1 and 6 g of COD/g N respectively.
Energy
H. Amiri; A. Babapoor; M. Fallahi-Samberan; N. Azimi; A. Hadidi
Abstract
Current research has simulated polymer oxide/metal oxide nanofibers (nanocomposites) through the COMSOL Multiphysics software. The oil was placed inside a cylindrical tank covered with a thin layer of phase change material nanocomposites. A combination of polyethylene glycol (PEG) as a the phase change ...
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Current research has simulated polymer oxide/metal oxide nanofibers (nanocomposites) through the COMSOL Multiphysics software. The oil was placed inside a cylindrical tank covered with a thin layer of phase change material nanocomposites. A combination of polyethylene glycol (PEG) as a the phase change material (PCM) and polyamide 6 (PA6) as a support matrix for nanofibers were used. The effect of some parameters such as the type of metal oxide nanoparticles (Al2O3, Fe2O3, TiO2, and CuO), the ratio of metal oxide to polymer (2% and 8% by weight), and time (600 and 4800 s) on some thermophysical properties such as changes in temperature, density and thermal conductivity were investigated. The simulation results showed that the most suitable system for thermal management is related to the presence of nanoparticles and PCM with the highest weight percentage. It was also found that the use of the nanofibers of phase change materials is very effective in improving thermal management and temperature control. As a result, they can be used as suitable materials for storing and transferring energy. The addition of 8% nanoparticles led to a 22.5% increase in thermal conductivity. Also, by providing the same initial and boundary conditions for all cases, the amount of melting in the presence of nanoparticles with a high percentage (8%) was higher than the with a low percentage (2%). As a result, the addition of nanoparticles to increase the melting rate can be very useful for various heat management purposes such as energy storage.
Environmental Engineering,
Zohreh khoshraftar; Ahad Ghaemi; Hossein Mashhadimoslem
Abstract
In this research, silica gel as a low-cost adsorbent for the uptake of carbon dioxide was investigated experimentally. The samples were characterized by XRD, BET and FT-IR. It shows that as pressure was increased from 2 to 8 bar, the CO2 adsorption capability improved over time. At a pressure of 6 bar ...
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In this research, silica gel as a low-cost adsorbent for the uptake of carbon dioxide was investigated experimentally. The samples were characterized by XRD, BET and FT-IR. It shows that as pressure was increased from 2 to 8 bar, the CO2 adsorption capability improved over time. At a pressure of 6 bar and a dose of 1 g of silica gel, the impact of temperature (25, 45, 65, and 85 °C) on the CO2 adsorption capacity (mg/g) was determined. The process behavior was investigated using isotherm, kinetics and thermodynamic models. As the temperature rises at a constant pressure, the adsorption capacity decreases. The experimental data of the carbon dioxide adsorption using silica gel have a high correlation coefficient with both Langmuir (0.998) and Freundlich (0.999) models. The results of the carbon dioxide adsorption kinetics with the silica gel adsorbent show that the correlation coefficient (R2) of the second-order model and Ritchie's second model are equal to 0.995 and have the highest value. The total pore volume was 0.005119 (cm3 g-1) and the specific surface area was 2.1723 (m2g−1). The maximum CO2 adsorption capacity at 25 °C near 8 bar was 195.8 mg/g.
E. Sharifzadeh; E. Tohfegar; M. Safajou Jahankhanemlou
Abstract
In this study, a comprehensive model was proposed in order to predict the tensile strength of nanocomposites considering the effects of the random orientation of nanoparticles, interphase properties and also the inevitable aggregation/agglomeration phenomenon. The model was structured based on the nanoparticle ...
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In this study, a comprehensive model was proposed in order to predict the tensile strength of nanocomposites considering the effects of the random orientation of nanoparticles, interphase properties and also the inevitable aggregation/agglomeration phenomenon. The model was structured based on the nanoparticle shape (e. g. platelet, cylindrical and spherical) so it could perfectly demonstrate the random orientation. It was revealed that neglecting the aggregation/agglomeration of the nanoparticles ( ) drastically rises the prediction error to about 12% while considering decreased the error to about 7-9% for samples with low content of nanoparticles (< 0.5 Vol.). Moreover, the model was completely capable of characterizing the polymer/particle interphase regardless of the polymer type and the nanoparticles shape. Model verification was accomplished by comparing its predictions with the tensile test results of the prepared nanocomposite samples of different compositions (Polystyrene/Silica, Polystyrene/Graphene Oxide and Polystyrene/Carbon nano-tubes). Also, the samples were subjected to TEM in order to qualitatively evaluate the behavior of the different shaped nanoparticles in the polystyrene matrix.
Separation Technology,
M. Zamani; S. R. Taghizadeh; A .R. Zahedipoor; M. Rahbari-sisakht
Abstract
Polysulfone-zinc oxide mixed matrix membrane (MMM) was fabricated. A polyamide layer was formed on the top surface of the membranes using interfacial polymerization process. The properties and structure of the membranes were investigated and the membranes were used for desalination in reverse osmosis ...
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Polysulfone-zinc oxide mixed matrix membrane (MMM) was fabricated. A polyamide layer was formed on the top surface of the membranes using interfacial polymerization process. The properties and structure of the membranes were investigated and the membranes were used for desalination in reverse osmosis process. Cross-sectional images of the membranes substrate showed that the addition of zinc oxide to the polymer matrix resulted in a denser structure and increased the thickness of the sponge-like layer near the lower surface of the membrane. The addition of zinc oxide to the polymer matrix decreased the surface contact angle of the membrane with water, thereby increasing the hydrophilicity of the membrane. The pure water flux of all membranes reduced at the beginning of the process and after 60 min remained almost constant at the values of 19.50 (Lm-2h-1) and 30.20 (Lm-2h-1) for the membrane made with plain polymer and the MMM, respectively. In the reverse osmosis process, the water flux of the membrane fabricated using plain polymer was 9.70 (Lm-2h-1) which increased by 39% and reached to 13.50 (Lm-2h-1) by the addition of zinc oxide nanoparticles. The salt rejection of plain polysulfone membrane was 92.5% which increased to 97.21% with the addition of zinc oxide to the polymer matrix. The addition of zinc oxide nanoparticles to the polymer matrix significantly decreased the water permeability to salt permeability ratio (B/A) from 40.54 to 14.35 (kPa).
Materials synthesize and production
K. Ashitosh; Manjunath S P; B. Prakash
Abstract
In this work, the phosphate bonded refractory was developed using magnesium potassium phosphate cement. The Cement was prepared from the caustic calcined magnesium oxide with the addition of mono potassium phosphate. The characterization of the cement was done by XRD and SEM to examine the change in ...
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In this work, the phosphate bonded refractory was developed using magnesium potassium phosphate cement. The Cement was prepared from the caustic calcined magnesium oxide with the addition of mono potassium phosphate. The characterization of the cement was done by XRD and SEM to examine the change in phase and morphology which occurs after the hydration of magnesium potassium phosphate cement which is in the struvite phase. To evaluate the physical, mechanical and thermal properties, refractory samples were casted and subsequently dried and fired at temperatures ranged from 1300 °C to 1500 °C. The effect of temperature on the bulk density, apparent porosity and crushing strength were analyzed. It was found that the properties of the chemically bonded refractory were better than the conventionally bonded calcium alumina cement refractory.
Transport Phenomena,
S. Amirzadeh; J.S Moghaddas
Abstract
Most industrial operating units are basically in contact with two gas and liquid phases. Bubble characteristics over the last years have been determined through different methods. In this project a mass transfer system has been designed for absorbing gas bubbles by liquid phase. The mass transfer and ...
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Most industrial operating units are basically in contact with two gas and liquid phases. Bubble characteristics over the last years have been determined through different methods. In this project a mass transfer system has been designed for absorbing gas bubbles by liquid phase. The mass transfer and hydrodynamic behavior in the wake of single rising air bubbles were investigated by using an image analysis method and empirical relations. By considering these methods, the overall bubble properties including the size of single bubble, shape, path, rising velocity and mass transfer coefficient were studied and measured. The investigation was developed with 0.15×0.15×0.35 m3 bubble column and nozzle diameter (0.5, 1, 1.5, 2, 2.5 mm) in different liquids considering viscose changes. Moreover, from the results obtained, it can be concluded that the increase of nozzle diameter increases the bubble diameter which results in reduction of velocity and mass transfer coefficient. This is a fact that, by raising the viscosity of liquid phase the bubble diameter stands at the highest level and on the contrary velocity and mass transfer coefficient stand at the lowest level. So according to these outcomes we can conclude that, the diameter of bubble depends on physical properties of fluids and has a direct relation with nozzle diameter.