Molecular interaction mechanism and performance evaluation in the liquid-liquid extraction process of ionic liquid-heptane-tertiary butanol based on molecular dynamics

Nowadays, organic solvents are more and more widely used in chemical industry, If the waste liquid is not recovered in time, this will also cause serious damage to the environment. In this work, [HMIM][OTF] and [BMIM][OTF], [OMIM][OTF] were used to separate n-heptane-t-butanol azeotropic system. From the molecular level, through the analysis of non-bonding interaction energy, spatial distribution function, radial distribution function and self-diffusion coefficient, explore [HMIM][OTF] and [BMIM][OTF], [OMIM][OTF] to separate n-heptane-tertiary butanol mixture Extraction mechanism. According to the MD simulation results, the non-bond interaction energy, radial distribution function, spatial distribution function and self-diffusion coefficient of different ionic liquid and different components were calculated and compared. The accuracy of force field parameters is verified by the density of each component. The results show that electrostatic energy plays a key role in the extraction process. The radial distribution function shows that [OTF]- plays a leading role in the extraction process. With the continuous growth of carbon chain, the extraction ability of ionic liquid is enhanced, but the solubility of raffinate is also enhanced. At the same time, ECOSAR toxicity analysis software also showed that [OMIM]+ had strong biological toxicity and was not suitable to be used as extractant. After comprehensive consideration, [HMIM][OTF] is selected as the best extractant. Finally, using [HMIM][OTF] as extractant, the process is designed and optimized. The final mole fraction of NHP is 99.73%, and the recovery of ionic liquid is 99.97%. This study provides certain guidance for the screening of ionic liquids as extractants.