مجيد شاه رخي

With increasing environmental concerns and the pressure of international regulations to reduce sulfur pollutants, novel and efficient methods for desulfurization are required. This research investigates the feasibility of using ionic liquids as green solvents for extracting sulfur compounds and, by utilizing the COSMO-RS model, provides new insights into the thermodynamic behavior and molecular interactions in these systems. The COSMO-RS model is recognized as a predictive tool for analyzing solubility behavior and phase equilibrium, which has been employed in this study to eva‎luate the performance of ionic liquids. In this research, a database of liquid-liquid equilibrium (LLE) data containing equilibrium data for 84 ternary systems composed of ionic liquid (1) - thiophene (2) - hydrocarbon (3) was first collected. Then, various cation and anion structures were examined, and the anionic and cationic structures were optimized for COSMO-RS calculations. Subsequently, quantum chemistry methods were used to compute and predict the surface charge distribution of molecules and analyze intermolecular interactions. These data provided a basis for predicting the thermodynamic behavior and phase equilibrium of different compounds. Another key aspect of this study is the comparison of the COSMO-RS model with QSPR models to assess the accuracy and efficiency of predictions. The comparison of results indicates that, statistically, COSMO-RS performs weaker than other models. However, by examining the results of both COSMO-RS and QSPR models in ternary phase diagrams at molar thiophene fractions below 10%, it is concluded that COSMO-RS provides more accurate results. This demonstrates its effectiveness in reducing the need for extensive experimental data, particularly in industrial applications, where separations are mainly performed within this range. Notably, the QSPR model has a strong dependency on experimental data, which is considered a drawback of this method. Additionally, the predicted results of the model were compared with COSMO-RS data available in scientific literature to validate the accuracy and reliability of the modeling. This study specifically examines the role of dipole moment in determining molecular polarity and its impact on the solubility behavior of sulfur compounds. The results indicate that imidazolium-based ionic liquids with asymmetric anions exhibit outstanding performance in the selective extraction of sulfur compounds. The proposed framework not only contributes to improving oil refining processes but also represents a significant step toward developing green technologies and reducing sulfur emissions into the environment.

گوگردزدايي , مايعات يوني , مدل‌هاي ترموديناميكي

COSMO-RS

Majid Shahrokhi

Dr.M.A.Sobati