Regular Article
Modeling and Simulation
Hajar seyfi; Sirous shafiei; Reza Dehghanzadeh; Parya Amirabedi
Abstract
Removal of Acrylonitrile (AN) from waste gas streams using biological methods has recently gained more attraction due to their better performance. The purpose of this research is modeling of the AN removal by a bio-filter. The model validation is done using the experimental data of a bench-scale bio-filter ...
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Removal of Acrylonitrile (AN) from waste gas streams using biological methods has recently gained more attraction due to their better performance. The purpose of this research is modeling of the AN removal by a bio-filter. The model validation is done using the experimental data of a bench-scale bio-filter bed column including yard waste compost and shredded hard plastics and thickened municipal activated sludge. In this work the kinetics of the biodegradation of Acrylonitrile is first investigated. Then equations of the biofilm and air are obtained at steady state and constant temperature. The unknown parameters of the model are determined by the least square optimization method along with solving the model equations using MATLAB. For inlet concentrations less than 1 g/m3 the model results show reasonable similarity to the experimental data. The effect of various parameters on bio-filter performance is evaluated. Peclet number, biofilm thickness and biomass concentration are the most important parameters respectively. The proposed model can be useful for design aims.
Regular Article
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 throughout the ...
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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, namely Shepherd and Stairmand 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 simulations computes 90.2% collection efficiency for the improved design. Computational fluid dynamics 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 those computed using Computational fluid dynamics.
Regular Article
Environmental Engineering,
Adel Panahadeh; Arsalan Parvareh; Mostafa Moraveji
Abstract
Central composite design (CCD) was employed to investigate the adsorption of Pb(II) and Zn(II) metal ions as well as methylene blue (MB) as an aromatic anion by a new EDTA/MnO2/CS/Fe3O4 synthesized nanocomposite. The effect of possible affective factors including contaminant concentration (20-200 mg/L), ...
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Central composite design (CCD) was employed to investigate the adsorption of Pb(II) and Zn(II) metal ions as well as methylene blue (MB) as an aromatic anion by a new EDTA/MnO2/CS/Fe3O4 synthesized nanocomposite. The effect of possible affective factors including contaminant concentration (20-200 mg/L), pH (2-8), adsorbent content (0.1-0.9 g/L), and contact time (10-110 min) were studied on the adsorption of the metal ions using response surface methodology (RSM). The highest removal percentages predicted by the model were 100.776% and 87.069%, respectively, for the removal of Pb(II) and Zn(II), that the value of more than 100% in the case of Pb(II) was due to the model error. The effect of the simultaneous presence of methyl blue (MB) and the metal ions in the aqueous solution on the adsorption rate of each metal ion was investigated. The study of adsorption isotherms in the single-component adsorption showed the dominance of Langmuir isotherm over the adsorption process of each pollutants (R2>0.99). The maximum adsorption capacities according to the Langmuir model were 310.4 and 136 mg/g for lead and zinc ions, respectively, and 421.1 mg/g for methyl blue. The results showed that the studied nanocomposite still has high efficiency after five consecutive adsorption-desorption cycles.
Regular Article
Reaction Engineering, Kinetics and Catalysts,
Gholamreza Moradi; hamed Hemmati; sahar rostami
Abstract
In this work, the effect of Si/Al ratio on the bimetallic (Ni-Co) zeolite supported catalysts on Dry Reforming of Methane (DRM) has been studied. Samples are prepared with impregnation and sol-gel method and then calcined at 550℃ for 2hrs. The catalysts were characterized by XRD, XRF, FESEM, BET and ...
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In this work, the effect of Si/Al ratio on the bimetallic (Ni-Co) zeolite supported catalysts on Dry Reforming of Methane (DRM) has been studied. Samples are prepared with impregnation and sol-gel method and then calcined at 550℃ for 2hrs. The catalysts were characterized by XRD, XRF, FESEM, BET and TGA. All samples were tested in a micro reactor at three different temperatures (i.e.700, 750, and 800 ℃). Micro reactor test results showed that 800 ℃ is the proper temperature for DRM. The catalyst with 5% wt. Ni and 2.5%wt. Co supported on γ-Alumina had shown a higher H2/CO ratio than the other samples. For zeolite supported catalysts when Ni/Co=2/1, surface area, and pore volume decreased but H2/CO ratio increased with increasing Si/Al ratio. Reverse Water Gas Shift (WGS) reaction was not very active when the catalyst and support showed a basic property. Also, the stability of the catalysts have been tested for 30h time on stream.
Regular Article
Environmental Engineering,
behnam mousazadeh; nima . mohammadi; touba hamoule
Abstract
Ziziphus nuts are abundant in Khuzestan province, Iran, and are considered as an unwanted natural biomass waste. The present study aimed to develop low-cost activated carbon from Ziziphus nuts as a new precursor for phosphate removal from the water environment. Iron oxide modification was performed to ...
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Ziziphus nuts are abundant in Khuzestan province, Iran, and are considered as an unwanted natural biomass waste. The present study aimed to develop low-cost activated carbon from Ziziphus nuts as a new precursor for phosphate removal from the water environment. Iron oxide modification was performed to simultaneously facilitate adsorbent separation via a simple magnetic process and increase phosphate removal capacity. The iron oxide/activated carbon composite (IOAC) was characterized using XRD, EDX, SEM, and BET methods. The specific surface area for IOAC reached 569.41 m2/g, comparable to that of commercial activated carbon. While other similar biomass-derived activated carbons reached phosphate removal capacity around 15 mg/g, IOAC demonstrated excellent phosphate removal performance as high as 27 mg/g. Also, IOAC showed fast adsorption kinetics, achieving equilibrium in only 60 minutes. On the basis of the results, the pseudo-second-order kinetic model was more consistent with the phosphate adsorption data onto the adsorbent than the pseudo-first-order model. The adsorption results were interpreted using Langmuir, Freundlich, and Webber-Morris diffusion models. The maximum Langmuir adsorption capacity was calculated to be 27 mg/L. The adsorbent was removed from the aqueous solution via a simple magnetic process.
Regular Article
Transport Phenomena,
Farhad Khoshnam; Hamid Ghasemkhani; Mohamad Reza Kamandar
Abstract
To improve quality attributes of final dried product and better management of the required energy, optimal process and technology is essential to dry agri-food materials. This work aimed at studying the dehydration characteristics and qualitative traits (color, shrinkage, rehydration ratio) of apple ...
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To improve quality attributes of final dried product and better management of the required energy, optimal process and technology is essential to dry agri-food materials. This work aimed at studying the dehydration characteristics and qualitative traits (color, shrinkage, rehydration ratio) of apple in a rotating-tray convective dryer under different operation variables. Furthermore, to model the dehydration curves, the utility of some well-known semi-theoretical models and artificial neural networks (ANNs) was evaluated. The drying experiments were conducted by practicing constant thickness of the samples (3 mm), different air temperatures (50‒85 °C) and flow rates (1 and 2 m s-1) as well as three tray rotating speeds (0, 6 and 12 rpm). In addition to significant (P < 0.05) reduction caused by increasing the temperature and flow rate, the process duration was considerably decreased by increment in the tray rotating speed. Moisture diffusion inside the slices (2.708×10-9‒8.337×10-9 m2 s-1) was facilitated by increasing the evaluated variables. The average values for activation energy changed from 20.47 to 23.80 kJ mol-1. In comparison with the thin layer models, artificial networks showed better performance in modeling of the curves. Although drying parameters did not significantly affected the studied quality properties, in general, higher drying air velocities and temperatures destroyed the quality of the final products.