RESUMO
In this study, the effect of operating parameters on drop behavior was investigated experimentally in an L-shaped pulsed sieve-plate column (LPSPC). LPSPC offers enhanced efficiency due to a high mixing rate provided by pneumatic or hydraulic pulsation of the liquids, which makes the dispersed phase drops coalesce and break. The response surface methodology (RSM) based on the central composite design (CCD) approach was applied for experimental modeling of three standard systems including toluene-water, butyl acetate-water, and butanol-water. Four parameters including pulsation intensity, interfacial tension, dispersion, and continuous phase velocities were examined in the experiments. Experimental results indicated that an increase in the pulsation intensity led to a decrease in Sauter mean diameter (SMD), and an increase in the flow rates of the phase cause an increase in SMD, although the effect of the flow rates on SMD was much lower than the pulsation intensity. Based on the obtained experimental data, new correlations have been proposed to predict SMD in two sections of the column tested by the goodness-of-fit statistics through analysis of variance. The coefficient of determination was achieved at 0.998 and 0.978 for horizontal and vertical sections, respectively, which demonstrated that the presented models estimated the experimental values very well. The optimum SMDs were obtained at 0.789 mm and 0.639 mm for the horizontal and vertical sections, respectively.
RESUMO
Most of the gas enters into a small portion of the rotating cylinder by increasing the rotational speed in a rotating cylinder. Navier-Stokes equations were used to evaluate gas behavior in this area. In this paper, the mass source calculated by the DSMC method at the boundary of the two regions has been used in the Onsager-Pancake equation and finite difference method was used to solve this equation. One of the assumed flow functions taking into account the effects of the scoop and thermal driving is the Olander's flow function. By combining the flow function that resulted from the Onsager-Pancake equation and the Olander's flow function, a new flow function is suggested, that in addition to applying the effect of thermal and mechanical driving, the feed driving added to it with the DSMC method. The results obtained using this new flow function in the modified diffusion equation by Onsager-Cohen, showing the resulted optimal separation power from that in comparison to the Olander's function occurs in a state where thermal driving is insignificant and scoop driving has increased. The effects of scoop drive have increased by increasing the feed value with the new flow function. Furthermore, the diffusion equations have been solved for 235UF6 and 238UF6 using the new flow function and it has been calculated the separation parameters.
RESUMO
In this work, Pseudomonas putida cells immobilized into chitosan beads (PICB) were synthesized to investigate the impact of microorganism entrapment on biosorption capacity of prepared biosorbent for U(VI) biosorption from aqueous solutions. Response Surface Methodology (RSM) based on Central Composite Design (CCD) was utilized to evaluate the performance of the PICB in comparison with chitosan beads (CB) under batch mode. Performing experiments under optimal condition sets viz. pH 5, initial U(VI) concentration 500mg/L, biosorbent dosage 0.4g/L and 20wt.% bacterial cells showed that the observed biosorption capacity enhanced by 1.27 times from 398mg/g (CB) to 504mg/g (PICB) that confirmed the effectiveness of cells immobilization process. FTIR and potentiometric titration were then utilized to characterize the prepared biosorbents. While the dominant functional group in the binding process was NH3(+) (4.78meq/g) in the CB, the functional groups of NH3(+), NH2, OH, COOH (6.00meq/g) were responsible for the PICB. The equilibrium and kinetic studies revealed that the Langmuir isotherm model and the pseudo-second-order kinetic model were in better fitness with the CB and PICB experimental data. In conclusion, the present study indicated that the PICB could be a suitable biosorbent for uranium (VI) biosorption from aqueous solutions.
