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Royaee S.J.,Research Institute of Petroleum Industry RIPI | Sohrabi M.,Amirkabir University of Technology | Sohrabi M.,Iran Academy of science
Industrial and Engineering Chemistry Research | Year: 2012

A photo impinging streams reactor was employed to study the degradation of phenol in aqueous solutions applying titanium dioxide nanoparticles as the reaction catalyst. The central composite experimental design method was applied to determine the pertinent operating parameters of such a process. These were phenol concentration, catalyst loading, pH of the slurry, and the feed flow rate. Residence time distribution (RTD) of the slurry phase within the reactor was measured using the impulse tracer method. A compartment model consisting of a number of mixed and plug flow regions was assigned to describe the flow pattern in the reactor. On the basis of such an arrangement and applying the Markov chains discrete time formulation, a three parameters model was derived for the RTD. The parameters of the theoretical RTD model were evaluated by comparing the latter with those determined experimentally. The RTD expression was applied in conjunction with the phenol degradation kinetic model to predict the apparent rate coefficient for such a reaction. The higher values observed for the apparent rate coefficient in impinging streams reactor than those available in the literature may be explained by the mass transfer limitations affecting the conventional reactors performance. © 2012 American Chemical Society.


Jafarikojour M.,Amirkabir University of Technology | Sohrabi M.,Amirkabir University of Technology | Sohrabi M.,Iran Academy of science | Royaee S.J.,Research Institute of Petroleum Industry RIPI | Hassanvand A.,Amirkabir University of Technology
Clean - Soil, Air, Water | Year: 2015

The photocatalytic degradation of toluene was studied in a newly designed continuous photoreactor. In this unit, TiO2 was immobilized on two different shapes of stainless steel disks. Twenty-eight disks coated with catalyst were placed alternately in the photoreactor in order to have a zigzag pattern in the gas flow along the reactor length. The structural properties of the coatings were examined using materials characterization techniques including X-ray diffraction (XRD) and field emission scanning electron microscope. The XRD results revealed that the intensity of the peak related to the anatase phase increases with increasing the number of coatings from two to six. The response surface methodology was applied to model and optimize the photocatalytic degradation of toluene. The Box-Behnken design was employed to analyze the simultaneous effects of toluene inlet concentration (20-100ppm), relative humidity (10-50%), flow rate of gas feed (100-500mL/min), and TiO2 loading (two to six times coating or catalyst loading of 0.274-0.924g/m2). The maximum predicted conversion of toluene was 61.11% at the optimum processing condition (relative humidity of 32%, catalyst loading of 0.924g/m2, flow rate of 100mL/min of gas feed, and initial toluene concentration of 20ppm). The experimental conversion of toluene was 60% at the optimum conditions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Jafarikojour M.,Amirkabir University of Technology | Sohrabi M.,Amirkabir University of Technology | Sohrabi M.,Iran Academy of science | Royaee S.J.,Research Institute of Petroleum Industry RIPI | Rezaei M.,Amirkabir University of Technology
Chemical Engineering Research and Design | Year: 2016

A new model was developed for the flow behavior of a counter-current liquid-liquid impinging streams reactor. As a modification of the well-known tanks-in-series model, the new model considers a cascade of descending-sized stirred tanks in series. This assumption is made because a distribution of the residence time exists for different liquid droplets depending on their initial elevation at the entrance to the system. The accuracy of this theoretical RTD model was analyzed through the comparison of the latter with that determined experimentally using the impulse tracer method. The results show that the presented model improves the predictions of the hydrodynamic behavior of impinging streams reactors. A comparison between the sum of the statistical parameter mean residual sum of squares (MRSS) for the new model with a number of previously presented models (the stirred tanks-in-series model, the gamma distribution with bypass (GDB) model, the Markov chains discrete time model, and the direct simulation Monte Carlo (DSMC) method) revealed that the proposed model is more capable of prediction of the hydrodynamic behavior of impinging stream reactors. © 2016 The Institution of Chemical Engineers.


Jafarikojour M.,Amirkabir University of Technology | Mohammadi M.M.,Sharif University of Technology | Sohrabi M.,Amirkabir University of Technology | Sohrabi M.,Iran Academy of science | Royaee S.J.,Research Institute of Petroleum Industry RIPI
RSC Advances | Year: 2015

The photocatalytic degradation of p-nitrophenol (PNP) using TiO2 particles immobilized on a fiberglass cloth was investigated in a novel design of a photo-impinging stream reactor. A spray painted method has been used for the coating process. The structural properties of the immobilized sample were examined using X-ray diffraction and a scanning electron microscope (SEM). The photocatalytic degradation results showed the good performance of the reactor. The flow regime within the reactor was characterized and modeled by applying a liquid residence time distribution. A compartment model consisting of four continuous stirred regions was assigned to describe the flow pattern in the reactor. A Langmuir-Hinshelwood kinetic scheme has been used to describe the degradation of p-nitrophenol and to examine the behavior of the reaction system. A comparison between the sum of the square errors of the experimental results and those predicted by the model for PNP degradation revealed that a good agreement exists between the two sets of data. © The Royal Society of Chemistry 2015.


Jafarikojour M.,Amirkabir University of Technology | Sohrabi M.,Amirkabir University of Technology | Sohrabi M.,Iran Academy of science | Royaee S.J.,Research Institute of Petroleum Industry RIPI | Rezaei M.,Amirkabir University of Technology
RSC Advances | Year: 2014

The photocatalytic degradation of volatile organic compounds is an innovative intensification technology. In this study, photocatalytic degradation of toluene has been investigated in a novel continuous immobilized photoreactor and the flow regimes were characterized and modeled by means of residence time distribution (RTD) of the gas phase. RTD analysis indicates that the flow regime in such a reactor cannot be considered as perfect plug and that a significant axial dispersion is available. A compartment model consisting of fourteen continuous stirred tank reactors was assigned to describe the flow pattern in the reactor. A Langmuir-Hinshelwood (L-H) kinetics scheme has been used to describe the degradation of toluene to model the behavior of the reaction system. A number of different assumptions were made, i.e. the perfect plug flow model, the plug-flow with axial dispersion model and the continuous stirred tank reactors in series model. A comparison was made between the sum of the square errors (SSE) for experimental and predicted degradation ratios for each flow model revealing that continuous stirred tank reactors in series were a better description for the photocatalytic degradation of toluene. © the Partner Organisations 2014.

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