Younes Amini

In this study, the removal of H ₂ S was investigated using hollow fiber membrane contactors (HFMCs). The absorbent fluid was a nanofluid containing carbon nanotubes, which was added to the absorbent fluid to enhance H ₂ S absorption. After the modeling and model validation of the HFMC, the nanofluid effect on the H ₂ S separation performance was discussed. A 2D HFMC model was considered, and COMSOL software was used for the model’s numerical solution. In the following, gas and nanofluid concentration distribution, velocity development profile in the membrane tube side, pressure drop in the tube side, the effect of gas flow rate on H ₂ S removal, the effect of hollow fiber number and the effect of liquid flow rate on H ₂ S removal were investigated. The results showed that adding the nanofluid to the absorbent fluid led to a significant increase in H ₂ S absorption in all cases. Additionally, the results indicated that increasing the gas flow rate and decreasing the absorbent fluid flow rate could result in a decrease in H ₂ S removal. The investigation of pressure variations in the absorption process from 1 to 10 bar also showed a slight increase in H ₂ S removal (approximately 5%). Furthermore, the conversion of the conventional fluid to the nanofluid resulted in an approximately 40% increase in H ₂ S removal.

Two different types of hollow‐fiber membrane contactors were used for CO₂ separation from the gas stream with monoethanolamine (MEA) absorbent and numerically investigated. After the model validation with experimental data, CO₂ removal efficiency, MEA concentration, and pressure drop variation were examined under different conditions by variation of some effective parameters such as gas stream velocity, absorption solution velocity, membrane porosity, and membrane tortuosity. Membrane tortuosity and porosity enhancement led to light decrease and light increase in CO₂ removal efficiency, respectively, but gas stream velocity enhancement significantly reduced the CO₂ removal efficiency.

In this paper, the removal efficiency of Cerium (Ce(ΙΙΙ)) and lanthanum (La(ΙΙΙ)) ions from aqueous solution using Amberlite XAD-7 resin impregnated with DEHPA(XAD7-DEHPA) was studied in the batch system. The adsorbent ( XAD7–DEHPA) was characterized by SEM–EDX, FTIR and BET analysis Techniques. The response surface methodology based on the central composite design was applied to model and optimize the removal process and evaluate operating parameters like adsorbent dose (0.05–0.065), initial pH (2–6) and temperature (15–55). Variance analysis showed that the adsorbent dose, pH and temperature were the most effective parameters in the adsorption of Ce(ΙIΙ)and La(IΙI) respectively. The results showed that the optimum adsorption condition was achieved at pH = 6, the optimum amount of absorbent and the equilibrium time equal to 0.6 gr and 180 min, respectively. According to the results, the adsorption percentage of Ce(ΙIΙ) and La(ΙΙΙ) ions onto the aforementioned resin were 99.99% and 78.76% respectively. Langmuir, Freundlich, Temkin and sips isotherm models were applied to describe the equilibrium data. From the results, Langmuir isotherm (R² (Ce) = 0.999, R² (La) = 0.998) was found to better correlate the experimental rate data. The maximum adsorption capacity of the adsorbent ( XAD7–DEHPA) for both Ce(IΙI) and La(III) was found to be 8.28 and 5.52 mg g⁻¹ respectively. The kinetic data were fitted to pseudo-first-order, pseudo-second-order and Intra particle diffusion models. Based on the results, the pseudo-first-order model and Intra particle diffusion model described the experimental data as well. In general, the results showed that ( XAD7–DEHPA) resin is an effective adsorbent for the removal of Ce(IΙI) and La(III) ions from aqueous solutions due to its high ability to selectively remove these metals as well as its reusability.

In the current research work, the flow behavior of a liquid–liquid extraction (LLE) process in a serpentine microchannel was analyzed. The simulation was performed using a 3D model and the results were found to be consistent with experimental data. The impact of the flow of chloroform and water on the flow model was also examined. The data indicate that once the aqua and organic phases flow rates are low and similar, a slug flow pattern is observed. However, as the overall flow rate raises, the slug flow transforms into parallel plug flow or droplet flow. An increment in the aqua flows while maintaining a constant organic phase flow rate results in a transition from slug flow to either droplet flow or plug flow. Finally, the patterns of flow rate in the serpentine micro-channel were characterized and depicted. The results of this study will provide valuable insights into the behavior of two-phase flow patterns in serpentine microfluidic devices. This information can be used to optimize the design of microfluidic devices for various applications. Furthermore, the study will demonstrate the applicability of CFD simulation in investigating the behavior of fluids in microfluidic devices, which can be a cost-effective and efficient alternative to experimental studies.