COSMO-RS prediction and experimental verification of 1,5-pentanediamine extraction from aqueous solution by ionic liquids

1,5-Pentanediamine (PDA) produced by biological fermentation becomes popular, but the separation of PDA from the broth is a typical difficult problem. In this work, the performance of 200 ionic liquids (ILs), formed by combining 25 cations and 8 anions, in the extraction of PDA from aqueous solution were evaluated using COSMO-RS model. The extraction mechanism was investigated with the help of σ-profile and interaction energy analyses. Both the cation and anion have impacts on the extraction efficiency, where cation mainly influences the interaction of IL with PDA and anion affects the hydrophobicity of IL. The IL composed of long alkyl-chain in cation and the anion of [PF6]- or [TF2N]-, which has the σ-profile more likely distributed in the nonpolar region but less distributed in the polar region, is favorable for extraction. The experimental liquid–liquid equilibrium demonstrated the effects of cation and anion on extraction performance, which validated the reliability of COSMO-RS model in IL screening for PDA extraction. The IL [IM-1,8][PF6] could serve as a promising extractant for the downstream separation process of the biological production of PDA.