Separation Technology,
Roohallah Bakhshi; Mostafa Moraveji; Arsalan Parvareh
Abstract
The polysulfone mixed matrix membranes (MMM) with different concentrations of graphene oxide (0, 0.25, 0.5 wt.% polymer) fabricated by a phase separation method. The cross-sectional structure and their upper surface were assessed by (SEM) surface roughness of the membranes assessed by (AFM). The mechanical ...
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The polysulfone mixed matrix membranes (MMM) with different concentrations of graphene oxide (0, 0.25, 0.5 wt.% polymer) fabricated by a phase separation method. The cross-sectional structure and their upper surface were assessed by (SEM) surface roughness of the membranes assessed by (AFM). The mechanical and thermal stability of the fabricated membranes evaluated as well. Carbon dioxide, nitrogen and methane separation from natural gas considered. An increase doping graphene oxide in matrix polymer outcome in a thicker sponge layer and disappearance of the finger-like cavities. From the outer surface morphology, the MMM presentation porosity a lower surface analogy the membrane neat. The membrane tensile strength and length of the membrane at fracture point increased slightly with an increase in graphene oxide concentration. transition Glass temperature membrane increased addition graphene oxide to the structure. From TGA analysis, in presence graphene oxide, thermal stability improved. From the gas permeation test, by addition of 0.25% graphene oxide to the polymer, CO2 permeability was increased from 61.22 GPU to 76.04 GPU, while addition of 0.5 wt.% resulted in a lower permeability (69.55 GPU). Nitrogen gas permeation flux of membranes decreased from 10.93 GPU to 3.91 GPU by addition of 0.50 wt.% of graphene oxide. Methane gas permeation flux is reduced from 11.31 GPU to 6.95 GPU and 4.92 GPU by addition of 0.25% and 0.50% graphene oxide, respectively. In conclusion, an increase in graphene oxide concentration increased carbon dioxide selectivity.
Separation Technology,
Saeed Ovaysi
Abstract
A new approach is proposed to evaluate various designs for gas-solid cyclone separators. This approach uses single-phase flow simulation results to find a quantitative measure of flow symmetry in a given cyclone. Flow symmetry is computed by averaging imbalances of non-axial velocities ...
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A new approach is proposed to evaluate various designs for gas-solid cyclone separators. This approach uses single-phase flow simulation results to find a quantitative measure of flow symmetry in a given cyclone. Flow symmetry is computed by averaging imbalances of non-axial velocities throughout the cyclone. Using this approach, two standard design methods are evaluated and the cyclone with a more symmetric flow pattern is chosen as a starting point for further design improvements by reducing the diameter of its vortex finder. Two-phase computational fluid dynamics (CFD) simulations compute 90.2 % collection efficiency for the improved design. CFD simulations reveal using a cascade of four cyclones results in an overall 99.98 % collection efficiency. Once installed in the actual industrial setting, the cyclone cascade achieves a 98.56 % collection efficiency and a particle size distribution which is in good agreement with CFD computed results.
Separation Technology,
S. Ghasemi; A. Behnamfard; R. Arjmand
Abstract
The thickening of the iron ore tailings allows process water to be partially recovered and recirculated, also it reduces the fresh water consumption, which results in lower operating costs and less environmental impacts. The settling characteristics of the mineral components of an iron ore tailing in ...
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The thickening of the iron ore tailings allows process water to be partially recovered and recirculated, also it reduces the fresh water consumption, which results in lower operating costs and less environmental impacts. The settling characteristics of the mineral components of an iron ore tailing in the thickening process may be different under various pulp conditions. Hence, the study of the characteristics of the mineral components of the iron ore tailings separately can provide very useful information about the thickening of an iron ore tailing. In this research, the settling behavior of the main mineral components of iron ore tailings including quartz and magnetite have been investigated under various operational conditions. The quartz and magnetite showed different settling behaviors, so as the maximum settling rate of quartz was achieved under different pulp conditions than that of magnetite was. There was a big difference between the maximum settling rates of quartz and magnetite, as the maximum settling rates of quartz and magnetite were 197 and 873 m/h respectively. In the thickening of an iron ore tailing, the pulp conditions must be set based on the settling behavior of the mineral component with the lowest settling rate.
Separation Technology,
P. Abbasi; k. Shayesteh; v. vahidfard; M. Hosseini
Abstract
In an Iranian zinc smelter plant, nickel and cadmium are removed from the electrolyte solution at the cold purification stage with the help of zinc powder. This study tries to investigate the optimal conditions for the removal of these impurities through the response surface methodology by examining ...
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In an Iranian zinc smelter plant, nickel and cadmium are removed from the electrolyte solution at the cold purification stage with the help of zinc powder. This study tries to investigate the optimal conditions for the removal of these impurities through the response surface methodology by examining the effects of effective parameters on the process. The results of the experiments showed that cadmium was cemented by zinc powder much more conveniently than nickel. The interplay of parameters showed that increasing the concentration of zinc powder can reduce the time and temperature of the entire reaction. It also neutralized the effect of the changes of pH and mixing speed. The optimum conditions for the simultaneous removal of nickel and cadmium were obtained at 75 °C, the pH of 4.5, the residence time of 45 min, the mixing speed of 500 rpm, and 2 g/l of zinc powder. Under optimal conditions, more than 99 % of nickel and cadmium were removed from the electrolyte solution.
Separation Technology,
M.R Omidkhah; H. Azami; L. Ghaheri
Volume 16, Issue 2 , June 2019, , Pages 1-13
Abstract
Nowadays, forward osmosis (FO) with many advantages in water treatment, are so attractive for researchers and investigators that the studies are going to optimize and increase its efficiency. However one of the most controversial operating malfunctions of FO process is fouling that limits the FO global ...
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Nowadays, forward osmosis (FO) with many advantages in water treatment, are so attractive for researchers and investigators that the studies are going to optimize and increase its efficiency. However one of the most controversial operating malfunctions of FO process is fouling that limits the FO global application. In the following research, vertically aligned carbon nanotube (VACNT) on alumina membrane is introduced with high water permeability and less biofouling potential in forward osmosis for seawater osmotically dilution systems. VACNT membranes were prepared via pyrolysis of polymer into the pores of alumina. The effect of the temperature of pyrolysis process on CNT’s structure are assessed which indicated crystallinity of the CNTs increase in higher pyrolysis temperature of 800 °C. A small scale setup is designed for FO analysis and measurements of biofouling, flux and the effect of osmotic pressure were measured. Furthermore, all analysis were compared with commercial TFC membrane and results demonstrated that VACNT membrane has 40% less biofouling potential and 2 times better flux results.
Separation Technology,
H. Sanaeepur; A. Ebadi Amooghin; A. Kargari; Mohammadreza Omidkhah; A. Fauzi Ismail; S. Ramakrishna
Volume 16, Issue 2 , June 2019, , Pages 70-94
Abstract
A new method is developed to enhance the gas separation properties of mixed matrix membranes (MMMs) by interior modification of an inorganic nano-porous particle. Ship-in-a-bottle (SIB), as a novel synthesis strategy, is considered to encapsulate a polyaza macrocyclic Ag-ligand complex into the zeolite ...
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A new method is developed to enhance the gas separation properties of mixed matrix membranes (MMMs) by interior modification of an inorganic nano-porous particle. Ship-in-a-bottle (SIB), as a novel synthesis strategy, is considered to encapsulate a polyaza macrocyclic Ag-ligand complex into the zeolite Y, which is resulted in a new host-guest nano-composite. It is consequently incorporated into a glassy polymer matrix to fabricate a novel MMM for CO2 separation. Accordingly, cellulose acetate (CA) with relatively low gas permeability is selected as the membrane polymeric matrix to provide an appropriate opportunity for better tracking the effect of incorporating the new synthesized nano-porous hybrids. The results showed a promising increase in both the CO2 permeability (45.71%) and CO2/N2 selectivity (40.28%) of the prepared MMM over its pristine CA membrane. It can be concluded that the proposed method makes it possible to fabricate novel MMMs with significant intensification in performance of the current MMMs.
Modeling and Simulation
M. Bahoosh; E. Kashi; S. Shokrollahzadeh; Kh. Rostami
Volume 16, Issue 1 , March 2019, , Pages 101-116
Abstract
Reverse osmosis is a commonly used process in water desalination. Due to the scarcity of freshwater resources and wastewater problems, a lot of theory and experimental studies have been conducted to optimize this process. In the present study, the performance of reverse osmosis membrane module of salt–water ...
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Reverse osmosis is a commonly used process in water desalination. Due to the scarcity of freshwater resources and wastewater problems, a lot of theory and experimental studies have been conducted to optimize this process. In the present study, the performance of reverse osmosis membrane module of salt–water separation was simulated based on computational fluid dynamics technique and solution-diffusion theory. Eight geometries of membrane modules four flat sheets, and four tubular membranes were investigated. It was found that if the membrane surface area and inlet flow rate were kept constant for the eight modules, the pressure drop and permeated flow rate would be approximately similar for some geometries (such as the performance of primary flat sheet channel is same as 3 tubular membranes with R=1/3 Rref). The results also showed that because of the phenomenon of concentration polarization, if it is possible to use more membranes with a smaller length, it can reduce the pressure drop and increase the permeation flux of water. Furthermore, the results showed that in similar conditions between the tubular and the plate membranes; the tubular one is more suitable for the water permeation due to its ease of construction and its ability to withstand ECP.
Separation Technology,
M. Shafiee; A. Akbari; B. Ghiassimehr
Volume 15, Issue 4 , November 2018, , Pages 17-26
Abstract
At this work, removal of Pb (II) using Lawsonia inermis (Henna) was studied. In recent years, use of low price adsorbent is taken into consideration. Adsorption experiments were performed in batch system at ambient temperature (25℃). The influence of some parameters such as time, initial metal concentration, ...
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At this work, removal of Pb (II) using Lawsonia inermis (Henna) was studied. In recent years, use of low price adsorbent is taken into consideration. Adsorption experiments were performed in batch system at ambient temperature (25℃). The influence of some parameters such as time, initial metal concentration, pH and adsorbent dose were investigated. The optimum conditions was obtained at pH of 6, 10 ppm of initial metal concentration, 80 min of contact time and 0.75 g/L of adsorbent dose. To study the adsorbent morphology, Scanning Electron Microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) was used before and after adsorption of Pb (II) ions. Sorption of Pb (II) was evaluated by Freundlich and Langmuir isotherms. The results indicate that the Freundlich isotherm model is better described the adsorption of Pb (II) than Langmuir isotherm model. Also, it is observed that, the pseudo-second-order kinetic model well fitted to experimental data .
Separation Technology,
N. Mostafazadeh; A.A. Ghoreyshi; K. Pirzadeh
Volume 15, Issue 4 , November 2018, , Pages 27-47
Abstract
In this study, ZIF-67 was synthesized through solvothermal method to remove Cr(VI) ions from aqueous solution. To improve the structural properties of ZIF-67 and its adsorption capacity, optimization of the synthesis conditions was carried out based on maximum Cr(VI) uptake. From experiments, the optimum ...
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In this study, ZIF-67 was synthesized through solvothermal method to remove Cr(VI) ions from aqueous solution. To improve the structural properties of ZIF-67 and its adsorption capacity, optimization of the synthesis conditions was carried out based on maximum Cr(VI) uptake. From experiments, the optimum condition was revealed as solvent: metal ion molar ratio of 4.6:1, ligand: metal ion molar ratio of 318:1 and temperature of 23℃. The physio-chemical properties of as-synthesized ZIF-67 were investigated by BET, XRD, FTIR and FESEM analyses. Effect of adsorption pH, adsorbent dosage, initial concentration and contact time on adsorption process was investigated. Based on the results, the maximum adsorption capacity of Cr(VI) was 26.27 mg/g which was obtained at 35℃, pH= 5, adsorbent dosage of 3 g/l and initial concentration of 107.82 mg/l. The equilibrium time for Cr(VI) adsorption varied from 180 min for low initial concentration of 9 mg/L to 240 min for a high initial concentration of 90 mg/L. For the synthesized ZIF-67, maximum uptake capacity was reported 26.27 mg/g at initial concentration of 107.82 mg/l. The equilibrium data were described better by Langmuir-Freundlich isotherm model than the other models at three different temperatures. Pseudo-second-order model fitted the experimental data better than pseudo-first-order one. Adsorption thermodynamics indicated that the adsorption process was endothermic and spontaneous in nature. The regenerability of ZIF-67 was also studied in three sequential cycles and the Cr(VI) adsorption was almost retained after two cycles.
Separation Technology,
F. Hosseini; M. Rahimi; O. jafari
Volume 15, Issue 4 , November 2018, , Pages 48-62
Abstract
In this work, extraction of propionic acid from the aqueous phase to the organic phase (1-octanol) was performed in T-junction microchannels and effects of channel diameter and fluid flow rate on the mass transfer characteristics were investigated. The two-phase flow patterns in studied microchannels ...
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In this work, extraction of propionic acid from the aqueous phase to the organic phase (1-octanol) was performed in T-junction microchannels and effects of channel diameter and fluid flow rate on the mass transfer characteristics were investigated. The two-phase flow patterns in studied microchannels with 0.4 and 0.8 mm diameters were observed. Weber number and surface-to-volume ratio were calculated for evaluating flow patterns. Moreover, the effect of volumetric flow rates on the extraction efficiency, volumetric mass transfer coefficient, and pressure drop was examined. Results showed that the pressure drop in the microchannel with 0.4 mm diameter is 2-2.7 times higher than that in the microchannel with 0.8 mm diameter. In both microchannels, with increase in flow rate, the extraction efficiency first increases and then decreases. In addition, at high flow rates (2.4, 4.5 and 6 mL/min), the extraction efficiency in the microchannel with 0.8 mm diameter increased up to the range of 7-14.9 % compared with that in the microchannel with 0.4 mm diameter.
Separation Technology,
Sh. Biswas; Md. M. Islam; M. M. Hasan; S.H. Rimu; M. N. Khan; P. Haque; M. M. Rahman
Volume 15, Issue 4 , November 2018, , Pages 63-80
Abstract
This paper reports the evaluation of adsorbing Cr (VI) ions on sorbent prepared from chitosan (CHT), a versatile derivative of chitin, and dodecyl amine modified locally available kaolinite clay (Bijoypur clay) (MC) that has excellent mechanical properties and great resistance to chemical and biological ...
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This paper reports the evaluation of adsorbing Cr (VI) ions on sorbent prepared from chitosan (CHT), a versatile derivative of chitin, and dodecyl amine modified locally available kaolinite clay (Bijoypur clay) (MC) that has excellent mechanical properties and great resistance to chemical and biological attack. The effect of the initial metal ion concentration, solution pH, contact time, and adsorbent dosages on the adsorption capacity of the composites was investigated. pH 4 is selected for better adsorption by the adsorbents. The adsorption abilities were studied over Cr (VI) ions using different adsorption isotherm such as Langmuir, Freundlich, and Dubinin-Radushkevich respectively. Langmuir isotherm is found better fitted with maximum adsorption capacity of 73 mg/g by composite SB-1. R2 obtained from Langmuir isotherm is 0.999 which indicates a monolayer adsorption on the adsorbent surface. The adsorption kinetics was also well described by the pseudo-second-order equation with a rate constant of 0.000302 g mg−1 min−1 at 25 ppm Cr(VI) concentration. The adsorption of Cr (VI) ions by the adsorbent were confirmed by FT-IR and X-RD analysis of the composites before and after Cr (VI) ion adsorption. The desorption percentage of the metal ion and the second cycle metal adsorption by regenerated (regenerated after the first adsorption by fresh adsorbent) adsorbent processed with 0.01N sulphuric acid shows a value of 78.23% and 68.12% respectively.
Separation Technology,
B. Medi; M.-K. Kazi
Volume 15, Issue 4 , November 2018, , Pages 81-92
Abstract
In this work, an improved single-column chromatographic (ISCC) separation process is proposed. The term `improved' refers to both conceptual and physical modifications compared to the available single-column processes, including a novel fraction collection scheme and allowing overlapped peaks from adjacent ...
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In this work, an improved single-column chromatographic (ISCC) separation process is proposed. The term `improved' refers to both conceptual and physical modifications compared to the available single-column processes, including a novel fraction collection scheme and allowing overlapped peaks from adjacent cycles. Also the fraction collection mechanism was modified in order to facilitate online monitoring. Another advantage of the ISCC process is its large degree of freedom as injection volume, cycle time, solvent flow rate, feed concentration, and fraction-collection intervals can all be decision variables in this process. The experimental implementation and validation is covered in this work. The results indicate successful operation of the ISCC process and accompanying peripherals for the separation of guaifenesin enantiomers. In particular, the tests confirmed the integrity of the online monitoring system and proved the capability of the process for 98% purification of the tested enantiomers with an advantageously shorter cycle time, which results in higher productivity.
Separation Technology,
M. Yasemi; M. Rahimi; A. Heydarinasab; M. Ardjmand
Volume 15, Issue 3 , September 2018, , Pages 15-33
Abstract
In this study, extraction of tannic acid using microchannel was investigated. Affective parameters were optimized. Different solvents including buthanol, ethylacetate and n-hexane as organic phase, methanol, propanol, ethanol and water as aqueous phase investigated. Microchannels with different confluence ...
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In this study, extraction of tannic acid using microchannel was investigated. Affective parameters were optimized. Different solvents including buthanol, ethylacetate and n-hexane as organic phase, methanol, propanol, ethanol and water as aqueous phase investigated. Microchannels with different confluence angles and diameters were examined. Microchannels with different confluence angles and diameters were examined. The effects of pH, temperature, and volumetric flow ratio and contact time of the two phases were investigated. The response surface methodology was used to optimize extraction yield of tannin from Quercus leaves in the employed microchannels. Based on this optimization, maximum yield was achieved at pH=2, temperature=33.1℃, volumetric flow ratio =1.2 and contact time of 25.35s. Results show that extraction-using microchannel has many advantages over traditional methods, including shorter time and higher economic efficiency. Moreover, microchannel provides smaller volume of fluids resulting in lower solvent consumption, lower waste production, shorter analytical times, smaller space requirements, and lower energy consumption.
Separation Technology,
N. Kakoui; M. Nikzad; A. A. Ghoreyshi; M. mohammadi
Volume 15, Issue 2 , May 2018, , Pages 3-21
Abstract
The present study investigates the potential applicability of the extracted pectin from sour orange pomace as adsorbent for Ni (II) removal from aqueous solution. Pectin extraction from the pomace was carried out using HCl and the highest pectin extraction yield of 26.75% was obtained. The Fourier transform ...
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The present study investigates the potential applicability of the extracted pectin from sour orange pomace as adsorbent for Ni (II) removal from aqueous solution. Pectin extraction from the pomace was carried out using HCl and the highest pectin extraction yield of 26.75% was obtained. The Fourier transform infrared (FTIR) spectroscopy analysis confirmed that the structure of the extracted pectin was similar to the commercial one. The morphology and chemical characteristics of pectin beads were analyzed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDX) techniques. The influence of several parameters including pH, initial metal concentration, adsorption temperature and time was studied to optimize nickel removal. The maximum Ni (II) removal of 85.1% was obtained at initial concentration of 20 mg/L and the highest adsorption capacity of 19.76 mg/g was achieved at nickel concentration of 100 mg/L. Kinetic and equilibrium studies were done to evaluate Ni (II) sorption from aqueous solution by the synthesized beads. Results showed that the sorption process follows a pseudo- second- order kinetic model. The equilibrium data were well correlated with Langmuir and Redlich-Peterson models by high regression coefficients.
Separation Technology,
A. Barzegari; Z. Shariatinia
Volume 15, Issue 2 , May 2018, , Pages 65-77
Abstract
Novel electrospun nanofibrous CS-PEO nerve conduits containing 0, 2.5 and 5% of green tea methanolic extract were developed and characterized by FE-SEM, FT-IR, TGA/DSC as well as tensile strength analysis. The FE-SEM images revealed that all of the nanofibers had an average diameter of ∼80nm. The ...
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Novel electrospun nanofibrous CS-PEO nerve conduits containing 0, 2.5 and 5% of green tea methanolic extract were developed and characterized by FE-SEM, FT-IR, TGA/DSC as well as tensile strength analysis. The FE-SEM images revealed that all of the nanofibers had an average diameter of ∼80nm. The swelling degree was decreased by increasing the GT amount from 2.5 to 5% and this might be attributed to the enhanced interactions of the NH2, C(O)NH2 and OH groups of chitosan and PEO polymers with the OH groups of GT leading to a less hydrophilic mat surface, thus reducing the attraction by the aqueous medium. Moreover, the swelling was the highest in acidic medium but it was decreased in the neutral environment and it had the least value within the alkaline medium. The CS-PEO-5%GT exhibited the highest antibacterial activity among three samples examined against both S. aureus and E. coli microorganisms. The CS-PEO-5%GT was proved to be a very suitable candidate to be used as nerve conduit due to its improved tensile and antibacterial activities.
Biomedical and Biotechnology,
A. Zabihollahpoor; P. Hejazi
Volume 15, Issue 1 , February 2018, , Pages 18-34
Abstract
In this study, the effects of some factors on bacterial growth and ferrous oxidation rates were investigated by Acidithiobacillus ferrooxidan in 250 ml shake flasks. One factor at a time (OFAT) design approach was used for preliminary evaluation of various factors affecting the process, such as pH, initial ...
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In this study, the effects of some factors on bacterial growth and ferrous oxidation rates were investigated by Acidithiobacillus ferrooxidan in 250 ml shake flasks. One factor at a time (OFAT) design approach was used for preliminary evaluation of various factors affecting the process, such as pH, initial ferrous and elemental sulfur concentrations, shaker agitation rate, and liquid to flask volume ratio. After that, optimal levels of effective last three factors to achieve high oxidation rate and cell growth rate were investigated using a full factorial design. It was obtained that agitation rate and liquid to flask volume, as well as their binary interaction, are significant factors on ferrous iron bio-oxidation rate. In contrast, initial high ferrous iron concentration was the only effective factor on the cell growth rate. Maximum bio-oxidation rate of 0.417 g/L was achieved at the media with Fe2+ ion concentration of 30 g/l, agitation rate of 200 rpm, and liquid to flask volume ratio of 20% by full factorial optimization, which is an about 40% increase compared to the result obtained in OFAT method. Then, the effect of step-wise adaptation of A. ferrooxidans to in high Fe2+ concentration was studied, and about 40% reduction in bacterial lag phase time, and 36 and 86% increase in bacterial growth rate and bio-oxidation rate were acquired, respectively.
Separation Technology,
N.A. Kostic; M.M. Milosavljevic; L.S. Pecic; S.Z. Babic; B.L. Milosavljevic; D.L. Milosevic; S.S. Krstic; B.V. Krstić
Volume 15, Issue 1 , February 2018, , Pages 73-88
Abstract
This paper describes a laboratory method for treatment of used engine oil FENIX SUPERIOR SAE 15W-40 with intention to decrease of sulfur and selected metal content at acceptable level. FENIX SUPERIOR SAE 15W-40, produced by manufacturer Joint Stock Company FAM Krusevac, is used for lubrication of the ...
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This paper describes a laboratory method for treatment of used engine oil FENIX SUPERIOR SAE 15W-40 with intention to decrease of sulfur and selected metal content at acceptable level. FENIX SUPERIOR SAE 15W-40, produced by manufacturer Joint Stock Company FAM Krusevac, is used for lubrication of the most modern four-stroke diesel and gas engines of passenger and commercial vehicles, engine construction, mining and agricultural machinery, as well as stationary power aggregates including highly overloaded engines working in harsh environmental conditions. Exhausted oil samples was obtained from the three sources: diesel and gas engines of passenger cars and agricultural machines – tractors were treated according to novel two step technology. In first step physical operations such as centrifugation, filtration and separation was applied in order to remove mechanical impurities (sludge), condensed material and water. In the second step chemical oxidation, using three agents: hydrogen peroxide, sodium hypochlorite, and potassium persulfate was applied to achieve removal of the sulfur containing compounds. Based on obtained results at laboratory level, a technology at semi-industrial level for the treatment of waste oil was proposed. New ecologically friendly technology developed for treatment of waste oil offer appropriate advantages in comparison to commercially available technologies.
Separation Technology,
A. Saberimoghaddam; V. Khebri
Volume 15, Issue 1 , February 2018, , Pages 89-101
Abstract
One of the most appropriate methods for elimination of trace impurities in helium is cryogenic adsorption process. So, in this study design and construction of cryogenic adsorption helium purification system (3 Nm3.hr-1, 80 bar) carried out using activated carbon as adsorbent at 77K. To evaluation of ...
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One of the most appropriate methods for elimination of trace impurities in helium is cryogenic adsorption process. So, in this study design and construction of cryogenic adsorption helium purification system (3 Nm3.hr-1, 80 bar) carried out using activated carbon as adsorbent at 77K. To evaluation of adsorption dynamics and effect of pressure on elimination of trace impurities, helium purification was performed from 10 to 70 bar. Results showed that helium can be purified from 99.95 % to 99.99999% at pressure of 60 bar using cryogenic adsorption process. Effect of regeneration condition on helium purity and recovery was investigated by three different regeneration methods: regeneration by helium at 40 °C and at 180 °C as purge gas, countercurrent to feed direction, and regeneration via vacuum. Results showed that regeneration of bed by vacuum can be proposed as most appropriated method because of maximum helium purity and high recovery of helium (98%).
Separation Technology,
Mo. H. Almasvandi; M. Rahimi
Volume 14, Issue 4 , December 2017, , Pages 17-31
Abstract
This paper reports the results of experimentally removing ammonia from synthetically prepared ammonia solution using a micro scale mixing loop air stripper. Effects of various operational parameters (such as: pH, air flow rate, wastewater flow rate and initial ammonia concentration) were evaluated. By ...
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This paper reports the results of experimentally removing ammonia from synthetically prepared ammonia solution using a micro scale mixing loop air stripper. Effects of various operational parameters (such as: pH, air flow rate, wastewater flow rate and initial ammonia concentration) were evaluated. By increasing the pH from 10 to 12.25 the amount of KLa increased from 0.26 to 0.73 hr-1. A considerable enhancement, about 150%, can be found for KLa by changing the air flow rate from 280 to 700 mL/min under fixed condition. The wastewater flow rate can also the value of KLa from 0.22 to 0.59 hr-1. The values of KLa increased only about 20% by changing the initial concentration of ammonia in the range between 50 and 500 mg/L. The results showed that improving in air stripping using microchannel was successfully carried out with enhancing overall volumetric mass transfer coefficient (KLa) and providing higher mass transfer capabilities compared with other types of strippers, even for lower amounts of used air. The enhancement of mass transfer is happened by efficient mixing induced by the employed microchannel. It has been demonstrated that wastewater flow rate and air flow rate have significant effects on KLa. The optimal stripping conditions and mathematical modeling for ammonia removal and the relation between the parameters were determined using Response Surface Methodology (RSM) with Central Composite Design (CCD) method. The results demonstrate the advantages the proposed system over convention stripper types.
Energy
E. GhasemiKafrudi; M. Amini; M. R. Habibi
Volume 14, Issue 4 , December 2017, , Pages 32-47
Abstract
The effects of greenhouse gases (GHG) on the growth of global warming, and increase of GHG and air pollutant emissions for energy production have forced the need of energy recovery which is normally wasted in industrial plant. The present research work focused on the GHG and air pollutant emissions reduction ...
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The effects of greenhouse gases (GHG) on the growth of global warming, and increase of GHG and air pollutant emissions for energy production have forced the need of energy recovery which is normally wasted in industrial plant. The present research work focused on the GHG and air pollutant emissions reduction employing pressure waste energy recovery. Pressure break-down via Joule-Thomson valve is a neat potential for waste energy recovery in gas refineries, which may also be provide by using a turbo-expander instead of commercial valves. Based on this ground, an exergy analysis is carried out for Joule-Thomson valve. The results showed that the exergy loss is higher than 6.5 MW and it is possible to recover about 1.9 MW of exergy loss. On the other hand, it was found that about 16900MWh of electrical energy can be produced by recovering the energy of waste pressure, which may leads to less consumption of the load and gas in refinery power unit. Consequently, equal the gas consumption reduction, 12056 ton CO2e of GHG and 54.6 ton of air pollutant emissions is reduced annually. Economical evaluation of utilizing a turbo-expander instead of a valve proved that this altering scenario is deducible and practical. Economical indexes, namely, IRR and NPV are found to be equal to 25.51% and 929571 US$, respectively. Moreover, sensitivity analysis conducted on each specific state certified the obtained results.
Modeling and Simulation
L. Mahmoodi; B. Vaferi; M. Kayani
Volume 14, Issue 4 , December 2017, , Pages 48-58
Abstract
Temperature distribution is a key function for analyzing and optimizing the thermal behavior of various process equipments. Moving bed reactor (MBR) is one of the high-tech process equipment which tries to improve the process performance and its energy consumption by fluidizing solid particles in a base ...
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Temperature distribution is a key function for analyzing and optimizing the thermal behavior of various process equipments. Moving bed reactor (MBR) is one of the high-tech process equipment which tries to improve the process performance and its energy consumption by fluidizing solid particles in a base fluid. In the present study, thermal behavior of MBR has been analyzed through mathematical simulation. Good agreement between the obtained results and both experimental data and analytical solution by self-adjoint method is observed. Mathematical results confirm that the average particle temperature linearly increases across the reactor length. Fluid temperature changes in a parabolic manner, and then it changes linearly. Increasing the Biot number ( ) results in increasing the temperature gradient inside the particle to a maximum value, and thereafter a decreasing pattern is observed. The numerical results confirmed that the finite difference method can be used for thermal analysis of the moving bed reactor.
Separation Technology,
P. Azadi; Sh. Hassanajili
Volume 14, Issue 3 , August 2017, , Pages 19-30
Abstract
In recent years, plasma treatments have given good results since they offer high technological efficiency with low waste generation. One of the most important characteristics of plasma methods is their action only on a thin surface layer, whereas the bulk of sample remains unchanged and the modified ...
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In recent years, plasma treatments have given good results since they offer high technological efficiency with low waste generation. One of the most important characteristics of plasma methods is their action only on a thin surface layer, whereas the bulk of sample remains unchanged and the modified material keeps its chemical and mechanical properties. In this research, polyurethane membrane surface was modified by low frequency plasma grafting with methacrylic acid and acrylamide monomers to alter solution-diffusion mechanism. We chose different parameters of plasma treatment and studied their effects toward maximum solubility, permeation and selectivity. The grafting on the surfaces was characterized by water contact angle measurement and atomic force microscopy. After confirming a successful grafting, we studied the effect of surface modification on permeation of CH4 and CO2. Significant increase in CO2 permeation and about 32 percent increase in CO2/CH4 selectivity was observed. Better results were obtained for low powers and acrylamide grafted surface.
Separation Technology,
M. Jadidi; N. Etesami; M. Nasr Esfahany
Volume 14, Issue 3 , August 2017, , Pages 31-40
Abstract
In this study adsorption of Cr(VI) from aqueous solution by Fe3O4 nanoparticles was investigated. Desorption process and recovery of nanoparticles using different solutions were then carried out, and it was observed that NaOH (0.5M) can remove 90% of adsorbed chromium ions. Following the completion of ...
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In this study adsorption of Cr(VI) from aqueous solution by Fe3O4 nanoparticles was investigated. Desorption process and recovery of nanoparticles using different solutions were then carried out, and it was observed that NaOH (0.5M) can remove 90% of adsorbed chromium ions. Following the completion of adsorption/ desorption cycles, it was determined that nanoparticles have still had a high ability of chromium ions adsorption after 4 cycles. In addition, it was found that when iron oxide nanoparticles were washed with NaOH solution, the adsorption efficiency increases in the next cycle. FTIR spectra and zeta potential analysis, demonstrated the increased in surface positively charged of nanoparticles leads to increased electrostatic attraction forces between the iron oxide nanoparticles and chromium ions which finally resulted in adsorption increasing. So in this research, pretreatment of nanoparticles with NaOH solution modifies the surface of Fe3O4 nanoparticles by increasing surface positively charged mechanism and the adsorption efficiency has improved in the next cycle.
Modeling and Simulation
A. Parvareh; . Parvizi
Volume 14, Issue 3 , August 2017, , Pages 55-64
Abstract
Abstract In this work, the role of appropriate mixing for mercaptan removal from Kerosene using caustic soda has been investigated in the pilot scale. Static mixer at different condition has been used as a passive mixing tool to achieve proper mixing and consequently high performance of mercaptan removal. ...
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Abstract In this work, the role of appropriate mixing for mercaptan removal from Kerosene using caustic soda has been investigated in the pilot scale. Static mixer at different condition has been used as a passive mixing tool to achieve proper mixing and consequently high performance of mercaptan removal. Two lengths of static mixer including 20 and 40 cm as well as two pitches 1 and 3 mm were considered in a straight line. NaOH was injected to the Kerosene line to remove ( convert it to disulfide) the mercaptan. The effect of mixer length, mixer element pitch at different flow rates of Kerosene, including 2, 18 and 30 mL/s was investigated on the mercaptan removal. The experimental results showed that the concentration of mercaptan in the pilot line outlet will decrease as the flow rates of Kerosene decreases. Also, at a fixed flow rate of Kerosene, increasing the length of the static mixer and decreasing its element pitch caused the mercaptan to decrease due to proper mixing. Computational Fluid Dynamics (CFD) modeling technique was employed to describe the experimental results, fluid flow pattern, and mixing performance. Qualitative predicted results of CFD modeling show a good agreement with the experimental data.
Separation Technology,
M. Azimi; S.J. Peighambardoust
Volume 14, Issue 3 , August 2017, , Pages 65-81
Abstract
In this work, we prepared the nafion/montmorillonite/heteropolyacid nanocomposite membranes for direct methanol fuel cells (DMFCs). The analyses such as X-ray diffraction (XRD), Fourier transform infrared (FTIR), and scanning electron microscopy (SEM) were conducted to characterize the filler dispersion ...
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In this work, we prepared the nafion/montmorillonite/heteropolyacid nanocomposite membranes for direct methanol fuel cells (DMFCs). The analyses such as X-ray diffraction (XRD), Fourier transform infrared (FTIR), and scanning electron microscopy (SEM) were conducted to characterize the filler dispersion and membrane structure in prepared nanocomposite membranes. XRD patterns of nafion-CsPW-MMT nanocomposites membranes showed the exfoliated structure of membranes by adding MMT and CsPW. SEM-EDXA results showed proper dispersion of nanoparticles in the membrane matrices. Addition of CsPW-MMT to nafion membranes increases water uptake and IEC due to increase hydrophilic groups in membranes. The proton conductivity results showed that proton conductivity increases by increasing amount of CsPW and decreasing of clay content in the membrane. Methanol crossover through polymer electrolyte membranes is a critical issue and causes an important reduction of performance in DMFCs. The developed intercalated nafion/CsPW/MMT nanocomposite membranes have successfully improved the membrane barrier properties due to the unique feature of MMT which contributed to the formation of a longer pathway towards methanol across the membrane. The lowest methanol crossover of the developed membranes in this study was 1.651×10-6 cm2 s-1 which was lower than re-cast nafion membrane (2.078×10-6 cm2 s-1). The methanol permeability was significantly reduced by the incorporation of MMT and increased by addition of CsPW in the nafion membrane. Finally, according to the selectivity results, the nafion-MMT-CsPW nanocomposite membrane with MMT mass fraction of 2.5% and CsPW mass fraction of 8% shows the best membrane selectivity and this nanocomposite membrane could be suitable for application in DMFCs.