Regular Article
Modeling and Simulation
Hajar seyfi; Sirous shafiei; Reza Dehghanzadeh; Parya Amirabedi
Abstract
The removal of Acrylonitrile (AN) from waste gas streams using biological methods, due to their better performance, has recently gained more attraction. The purpose of this research is modeling the AN removal by a bio-filter. The validation of the model is done by using the experimental data of a bench-scale ...
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The removal of Acrylonitrile (AN) from waste gas streams using biological methods, due to their better performance, has recently gained more attraction. The purpose of this research is modeling the AN removal by a bio-filter. The validation of the model is done by 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 a 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 similarities to the experimental data. The effect of various parameters on the bio-filter performance is evaluated. The Peclet number, biofilm thickness and biomass concentration are the most important parameters. The proposed model can be useful for design purposes.
Regular Article
Transport Phenomena,
Hamid Ghasemkhani; Farhad Khoshnam; Mohamad Reza Kamandar
Abstract
To improve quality attributes of the final dried product and execute a better management of the required energy, optimal process and technology it is essential to dry agri-food materials. This work is aimed at studying the dehydration characteristics and qualitative traits (color, shrinkage, rehydration ...
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To improve quality attributes of the final dried product and execute a better management of the required energy, optimal process and technology it is essential to dry agri-food materials. This work is aimed at studying the dehydration characteristics and qualitative traits (color, shrinkage, rehydration ratio) of apple in a rotating-tray convective dryer with different operational variables. Furthermore, to model the dehydration curves, the usage of some well-known semi-theoretical models and artificial neural networks (ANNs) was evaluated. The drying experiments were conducted by applying the 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 the increment in the tray rotating speed. The moisture diffusion inside the slices (2.708 × 10-9 ‒ 8.337 × 10-9 m2 s-1) was facilitated by increasing the values of evaluated variables. The average values for the 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 the curves. Although drying parameters did not significantly affect the quality of studied properties, in general, higher drying air velocities and temperatures deteriorated the quality of the final products
Regular Article
Environmental Engineering,
Adel Panahadeh; Arsalan Parvareh; Mostafa Moraveji
Abstract
The 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 the contaminant concentration (20-200 ...
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The 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 the contaminant concentration (20-200 mg/L), pH (2-8), adsorbent content (0.1-0.9 g/L), and contact time (10-110 min) on the adsorption of the metal ions using response surface methodology (RSM) were studied. 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’s 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 the adsorption isotherms in the single-component adsorption showed the dominance of Langmuir isotherm over the adsorption process of each pollutant (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 had high efficiency after five consecutive adsorption-desorption cycles
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 is aimed to develop low-cost activated carbon from Ziziphus nuts as a new precursor for the removal of phosphate from the water environment.the iron oxide modification was ...
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Ziziphus nuts are abundant in Khuzestan province, Iran, and are considered as an unwanted natural biomass waste. The present study is aimed to develop low-cost activated carbon from Ziziphus nuts as a new precursor for the removal of phosphate from the water environment.the iron oxide modification was performed to simultaneously facilitate the adsorbent separation via a simple magnetic process and increase the 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 the commercial activated carbon. While other similar derived-from-biomasses activated carbon reached the phosphate removal capacity of around 15 mg/g, IOAC demonstrated the excellent phosphate removal performance of as high as 27 mg/g. Also, IOAC showed fast adsorption kinetics, achieving equilibrium in only 60 minutes. According to the results, the pseudo-second-order kinetic model was more consistent with the data related to the phosphate adsorption onto the adsorbent than the pseudo-first-order model. The adsorption results using Langmuir, Freundlich, and Webber-Morris diffusion models were interpreting. 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
Reaction Engineering, Kinetics and Catalysts,
Gholamreza Moradi; Hamed Hemmati; Sahar rostami
Abstract
In this work, the effect of the Si/Al ratio on the activity of zeolite supported bimetallic (Ni-Co) catalysts for Dry Reforming of Methane (DRM) has been studied. Samples are prepared with impregnation and sol-gel methods and then calcined at 550 °C for 2 h. The catalysts were characterized by XRD, ...
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In this work, the effect of the Si/Al ratio on the activity of zeolite supported bimetallic (Ni-Co) catalysts for Dry Reforming of Methane (DRM) has been studied. Samples are prepared with impregnation and sol-gel methods and then calcined at 550 °C for 2 h. 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 °C). Micro reactor test results showed that 800 °C was the proper temperature for DRM. The catalyst with 5 wt % of Ni and 2.5 wt % of Co supported on γ-Alumina have shown a higher H2/CO ratio than other samples. For the zeolite supported catalysts when Ni/Co=2/1, the surface area and pore volume decreased but the H2/CO ratio increased by increasing the Si/Al ratio. Reverse the Water Gas Shift (WGS) reaction was not very active when the catalyst and support showed a basic property. Also, the stability of the catalysts has been tested for 30h on stream.
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 ...
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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.