Journal of Chemical and Petroleum Engineering
Year:2010 | Volume:43 | Issue:2|Papers Count:8

In this work, the adsorption of carbon dioxide from model flue gas on different adsorbents has been investigated. Using simplified modeling, parameters such as the total mass transfer coefficient and the effective diffusivity have been determined. Experiments were carried out in two sections: firstly, adsorption of pure carbon dioxide on different adsorbents was measured at pressures ranging from 30 to 120 kPa and a temperature of 25°C using a low pressure volumetric adsorption system. In this section, activated carbon, Norit RB3 and Eurocarbon showed significant uptake. Secondly, using a dynamic adsorption system, the breakthrough curve of carbon dioxide was obtained from a column with an inner diameter of 1cm and a length of 28cm. The calculated standard experimental error was 0.19. This error showed that the applied model is suitable for predicting adsorption of carbon dioxide from model flue gas.

Based on the importance of drops' behavior in liquid-liquid extraction, the maximum sauter mean drop diameter has been investigated and correlated in a counter-current spray extraction column with two chemical systems. Spargers were set of nozzles in all experiments. Studying the effects of several parameters on drops size, some correlations were estimated by the last available version of software “Eviews”. Finally, the best empirical correlation was selected based on lowest error and highest conformity with the experimental data. It’s notable that, in this paper, the maximum sauter mean drop diameter was investigated and correlated for first time in a spray extraction column. Comparing final selected correlation with experimental data, it’s observed that the correlation mentioned above has an error about 4.22% with empirical data that shows the good accuracy of this correlation.

In the present research, the yield of extracted oil from grape seeds (planted and grown in Shahrood), was studied by ethanol solvent extraction method. The grape seed essential oil has many applications in pharmaceutical, cosmetic and food industries. The algorithm of influential parameter study was designed by a four factorial design in two levels. The ethanol purity percentage, temperature, particle size and extraction time as the main parameters were studied by factorial design experiments. The effect of parameters were investigated by analysis of variance on the yield of extracted oil and it was concluded that increasing temperature, time and ethanol concentration has positive effect in oil extraction, whereas increasing particle size showed the inverse effect. The particle size was the most effective parameter among the others. In addition, study of the effect of binary interactions has shown no significant effects of ethanol–temperature, ethanol- time and particle size-time, whereas interaction of ethanol-size was important in the yield of extraction. A regression model was presented as a function of main factors and ethanol-size interaction for the yield of extracted oil and the optimized conditions were proposed. On the base of the results, using ethanol with 96% purity at temperature of 60 C for 60 min. extracted 0.24 gr oil/gr seed from particles with mean size of 0.6 mm.  

Nowadays, membrane processes are widely used for high purity Nitrogen production. Separation of air by membranes is a flexible process in which the investment and operational costs are lower than for example adsorption or cryogenic processes. Such processes are based on relative permeability of air components which are transported by the pressure difference between two sides of the membrane. Mathematical equations for modeling and simulation of membrane air separation were solved by both HYSYS simulator without any need of external programming out of the simulator environment, and linking Excel to ASPEN PLUS without any need for compile or multiple processes. Countercurrent flow conditions through the membrane, and hollow fiber type membrane were assumed to be applicable. By doing such simulation, the separation percentage of air components in two product streams, and also purity percentage of each stream could be determined. Results of simulations by these two industrial simulators were compared with experimental data and a good consistency was reached. The proposed method can be used for simulation of non-ideal systems successfully.

Alkaline Protease enzyme produced from Bacillus Licheniformis PTCC1331 in optimum Condition(Temperature 37°C, 150 rpm, PH=10), is immobilized in different concentrations of Sodium Alginate using entrapment method, to increase its thermal resistance in detergents, and its activity is measured thereafter. Maximum enzymatic activity of 46[u/g]carrier was obtained in 2%w/v Sodium alginate solution. Investigations on different temperatures on enzymatic activity of free and immobilized enzymes shows that relative activity of free enzyme decreases in temperatures more than 45°C but immobilized enzyme maintains its activity up to 55°C and is more stable than free enzyme. Moreover stability of free and immobilized enzyme is studied in 40 & 50°C. Immobilized enzyme is more stable in 40°C than 50°C. Effect of pH on free and immobilized enzyme is also studied between pH 7 to 12.Both free and immobilized enzymes are more stable in pH 7 to 8 and activity of immobilized enzyme is more than free enzyme in this range. As it is resulted using the best method of immobilization, enzyme would be more stable and its usage would be more effective in industry.

A mathematical model is described and applied for adsorption process of ethyl acetate from supercritical CO2 stream on activated carbon particles. This model has the ability of illustrating variation of effluent concentration towards different parameters such as flow rate, temperature and pressure. In this research, a vast area of operational conditions is experienced. Mass transfer resistance from bulk to solid surface and diffusion resistance inside the porous solid are considered. The bulk supercritical CO2 fluid is considered with axial dispersion along the bed. The adsorption mechanism in solid phase has been considered kinetically as a reversible first order adsorption/desorption reaction. Results of the breakthrough model are in acceptable agreement with experimental data. 

The interface of nano-and biotechnology is a new field of research came into action with developments in various branches of nanotechnology. Mimicking natural nanosystems including nanoscale molecular motors has attracted the attention of many researchers. Molecular motors considered in this research are nanoscale proteins holding interacellular transportation which are consisted of kinesin, dynein and myosin. Many efforts have been made to model and simulate the behavior of molecular motors focusing either on dynamics of individual motors or macroscopic behavior of motors or organelles using density variations. In this research, the intracellular mass transport by molecular motors is investigated using a macroscopic approach based on Dinh and co-workers model reporting a generalized theory for spatial patterns of intracellular organelles exhibiting one of the four distinct patterns, namely aggregation, hyperdispersion, radial dispersion and areal dispersion. Dinh and co-workers approximated the set of differential equations describing the system with an advection-diffusion equation for which the solution was given only by introducing the 4 distribution regimes. In this work in addition to presenting the numerical solution of the approximated equation, the set of differential equations describing the distribution of 15 organelles at 4 different regimes has been numerically solved using two sets of boundary conditions. It was found that the results are sensitive to boundary conditions.

Platinum extraction from different secondary sources has been experimentally tested by many researchers. In this article, dissolution of platinum in aqua-regia solution from two types of spent catalysts (reforming and nitric acid production) was kinetically studied. A variety of kinetic models for heterogeneous solid-liquid reactions, including homogeneous diffusion model, shrinking core model, and the power law model were examined. However, these were not able to robustly predict the experimental data. Another model, the Elovich equation, fitted the kinetics data fairly well for both catalysts. The relation between the Elovich equation parameters (a and a) and the process conditions, i.e., temperature and liquid/solid ratio was obtained. It was realized that different catalyst matrices only modestly affect the a parameter, which is representative of the initial rates (only a function of initial concentrations and temperature). In contrast, the other term, a, which is a function of the catalyst structure and the liquid/solid ratio, was found to be rather different for the two catalysts.