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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Challenges in Nano and Micro Scale Science and Technology
- نوع مقاله: Journal Article
- کلمات کلیدی: CO2 absorption,Piperazine,SiO2 nanoparticles,CO2 gas mass transfer,Nano-solvent
- چکیده:
- چکیده انگلیسی: This study investigates the effect of adding SiO2 nanoparticles to the amine solution on the mass transfer coefficients with the aim to obtain effective solvent in the CO2 capturing process. An aqueous mixture of the methyl di-ethanol amine (MDEA), activated by blending with Piperazine (PZ) (a-MDEA), was considered as base absorption solvent. The addition of SiO2 nanoparticles with six different concentrations to the base absorption solvent was then studied. The absorption process took place in an agitated batch reactor at 40 ºC. Considering the gas pressure drop in the reactor the CO2 absorption and mass transfer rates were obtained for all types of the solvents and were compared with each other. Results revealed that two regimes of fast and slow were involved in the CO2 absorption process, where the overall mass transfer of the fast regime was more than 100 times that of the slow one. The results indicated that the liquid phase controlled the mass transfer in the CO2 absorption process. Furthermore, the maximum increase in the absorption rate was happenned when the concentration of SiO2 nanoparticles was set at 25 ppm in the solvent. In this regard, the enhancement was at least 85% increase in the overall mass transfer coefficient. The findings of this study can be used to design new nanoparticle-based solvents and reduce the cost of the CO2 capturing process.
- انتشار مقاله: 26-09-1398
- نویسندگان: Hossein Shahraki,Jafar Sadeghi,Farhad Shahraki,Davod Mohebbi-Kalhori
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Renewable Energy and Environment
- نوع مقاله: Journal Article
- کلمات کلیدی: Response surface methodology,Regression model,Direct methanol fuel cell stack,maximum power density
- چکیده:
- چکیده انگلیسی: The power density of a direct methanol fuel cell (DMFC) stack as a function of temperature, methanol concentration, oxygen flow rate, and methanol flow rate was studied using a response surface methodology (RSM) to maximize the power density. The operating variables investigated experimentally include temperature (50-75 °C), methanol concentration (0.5-2 M), methanol flow rate (15-30 ml min-1), and oxygen flow rate (900-1800 ml min-1). A new design of the central composite design (CCD) for a wide range of operating variables that optimize the power density was obtained using a quadratic model. The optimum conditions that yield the highest maximum power density of 86.45 mW cm-2 were provided using 3-cell stack at a fuel cell temperature of 75 °C with a methanol flow rate of 30 ml min-1, a methanol concentration of 0.5 M, and an oxygen flow rate of 1800 ml min-1. Results showed that the power density of DMFC increased with an increase in the temperature and methanol flow rate. The experimental data were in good agreement with the model predictions, demonstrating that the regression model was useful in optimizing maximum power density from the independent operating variables of the fuel cell stack.
- انتشار مقاله: 14-05-1398
- نویسندگان: Shima Sharifi,Rahbar Rahimi,Davod Mohebbi-Kalhori,Can Ozgur Colpan
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Renewable Energy and Environment
- نوع مقاله: Journal Article
- کلمات کلیدی: Microbial fuel cell,Ceramic Membrane,Domestic Wastewater,Gerischer element,constant phase element
- چکیده:
- چکیده انگلیسی: The effect of the thickness of ceramic membrane on the productivity of microbial fuel cells (MFCs) was investigated with respect to the electricity generation and domestic wastewater treatment efficiencies. The thickest ceramic membrane (9 mm) gained the highest coulombic efficiency (27.58±4.2 %), voltage (681.15±33.1 mV), and current and power densities (447.11±21.37 mA/m2, 63.82±10.42 mW/m2) compared to the 6- and 3-mm thick separators. The results of electrochemical impedance spectroscopy (EIS) analysis were investigated to identify the internal resistance constituents by proposing the appropriate equivalent electrical circuit. The Gerischer element was modeled as the coupled reaction, and diffusion in the porous carbon electrodes and the constant phase element was assimilated into the electrical double-layer capacitance. The thickest ceramic (9 mm) was found to have the largest ohmic resistance; however, owing to its superior barrier capability, it provided more anoxic conditions for better accommodation of exoelectrogenic bacteria in the anode chamber. Therefore, lower charge transfer, fewer diffusional impedances, and higher rates of anodic reactions were achieved. Excessive oxygen and substrate crossover through the thinner ceramics (of 6 and 3 mm) resulted in the suppressed development of anaerobic anodic biofilm and the accomplishment of aerobic substrate respiration without electricity generation.
- انتشار مقاله: 31-03-1398
- نویسندگان: Vajihe Yousefi,Davod Mohebbi-Kalhori,Abdolreza Samimi
- مشاهده
- جایگاه : پژوهشی
- مجله: Advances in Environmental Technology
- نوع مقاله: Journal Article
- کلمات کلیدی: optimization,Wastewater treatment,Membrane technology,Reuse,Bentazon
- چکیده:
- چکیده انگلیسی: Although bentazon is widely used as an agricultural herbicide, it is harmful to humans and poses many environmental threats. This study focused on the treatment of wastewater contaminated with bentazon pesticides using membrane technology. In this regard, low-pressure reverse osmosis (RO) was employed as it has already been used in the removal of other micro-pollutants. The effects of process variables on water flux and bentazon rejection were studied: temperature, pressure, and bentazon feed concentration. Based on central composite design (CCD), the quadratic model was engaged to correlate the process variables with the water flux and the bentazon removal responses. The obtained results showed that the bentazon rejection increased by enhancing the pressure while it decreased at higher feed solution concentration. However, with increasing temperature, the amount of bentazon removal was reduced. A bentazon rejection efficiency of 100 % could be achieved under optimum conditions (i.e., the temperature of 29.8 ℃ and hydrostatic pressure of 12.6 bar for a feed solution concentration of 66.9 mg/L). Therefore, reverse osmosis can effectively remove bentazon.
- انتشار مقاله: 01-03-1399
- نویسندگان: Mohammad Nematzadeh,Abdolreza Samimi,Soheila Shokrollahzadeh,Davod Mohebbi-Kalhori
- مشاهده
- جایگاه : پژوهشی
- مجله: Advances in Environmental Technology
- نوع مقاله: Journal Article
- کلمات کلیدی: Biodegradation,Biofilter,Formaldehyde,Packing materials,Contaminated air
- چکیده:
- چکیده انگلیسی: The removal of formaldehyde from contaminated air was investigated via three laboratory-scale biofilters packed with different materials: a mixture of compost and woodchips (І), the natural clinoptilolite zeolite particles in the original form (II), and the mixture of zeolite/activated carbon (III). The biofilters were inoculated using aerobic sludge. The average removal efficiencies of 97.5%, 90%, and 93.5% were obtained at a 100 s empty bed residence time (EBRT) and 20 mg/m3 inlet concentration of formaldehyde for the biofilter of configurations І, II, and III, respectively. Also, the performance of the reactors was investigated at different EBRTs of 20, 30, 60, and 100 s, and the maximum elimination capacity of 2840 mg/m3.h was achieved at the lowest EBRT (20 s) for the biofilter of configuration II. Increasing the inlet formaldehyde concentration from 20 mg/m3 to 80 mg/m3 led to the maximum formaldehyde removal efficiency of 82% for the biofilter of configuration III. Therefore, a comparison of the results of the biofilters' performances showed that the biofilter of configuration III had the best performance, which was validated by obtaining a higher mass transfer coefficient. However, the biofilter of configurations II and III achieved steady-state conditions in a shorter time.
- انتشار مقاله: 26-09-1398
- نویسندگان: Elham Narooei,Davod Mohebbi-Kalhori,Abdolreza Samimi,Mortaza Zivdar
- مشاهده