Extraction of l-Tryptophan by Hydroxyl-Functionalized Ionic Liquids

Abstract

In this work, several hydroxyl-functionalized ionic liquids (ILs) were synthesized and used to extract tryptophan from the aqueous phase. The experimental results indicated that the hydroxyl-functionalized ILs presented better extraction ability than the dialkylimidazolium-based ILs. The extraction efficiency was significantly influenced by the pH of the aqueous phase. Moreover, the cationic form of tryptophan preferred to transfer into the IL phase, thereby suggesting a cation-exchange extraction mechanism. Driving forces of the extraction processes included hydrogen bonding, hydrophobicity, π−π stacking, and the screening effect. Among these factors, hydrogen bonding was the main parameter, as suggested by the results of thermodynamic analysis. After extraction, [C 1 C 6 OHim]NTf 2 could be reused by using the pH swing effect. These findings demonstrate that [C 1 C 6 OHim]NTf 2 is a good alternative to conventional solvents for recovering tryptophan from the aqueous phase.

Aqueous Biphasic Systems Containing Customizable Poly(Ionic Liquid)s for Highly Efficient Extractions

“…Because of the good phase separation ability of P[BVIm]Br‐based ABSs, we evaluated their extraction performance for bioactive molecules. The chemical structures of the bioactive molecules are represented in Figure c. Tryptophan (Trp) and phenylalanine (Phe) are essential amino acids, which are widely used in food and pharmaceutical industries . In addition, because they consist of both a hydrophobic aromatic ring and a polar hydroxyl and carboxyl group, they are usually used as model solutes in ABS extraction experiments.…”

Ionic Liquids: Efficient Media for the Lipase-Catalyzed Michael Addition

“…The ILs, [C 1 C 4 im]BF 4 (99%), [C 1 C 4 im]PF 6 (99%), and [C 1 C 4 im]NTf 2 (99%) were supplied by the Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences (Lanzhou, China). The ILs, [C 1 C 6 OHim]NTf 2 , [C 1 C 3 OHim]NTf 2 , [C 4 C 3 OHim]NTf 2 , ([C 4 C 11 OHim]NTf 2 , and [C 1 C 11 OHim]NTf 2 were synthesized on the basis of our early work [ 45 ]. All the other reagents were of an analytical grade unless stated otherwise.…”

Recovery of Lithium from Brine with a High Mg/Li Ratio Using Hydroxyl-Functionalized Ionic Liquid and Tri-n-butyl Phosphate

“…Shi et al [29,30] showed that an extraction efficiency of over 90% was achieved using TBP and PF6or NTf2 --based ILs. It is apparent that NTf2 --based ILs have higher extraction efficiency of Li + and stability than PF6 --based ILs [31]. However, to our knowledge, there are no studies about the whole extraction process including extracting, washing, stripping and regeneration with NTf2 --based ILs as co-extraction reagent.…”

“…Hydroxyl-functionalized ILs are superior to imidazolium-based ILs in separation fields because of their higher viscosity, thermal stability, extraction ability and selectivity of metal ions [31][32][33][34]. Yang et al [34] investigated Li + recovery from alkaline brine using hydroxyl-functionalized ILs, 1-hydroxyethyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)imide ([OHEMIM][NTf2]), and a neutral ligand, trialkyl phosphine oxide (Cyanex923) as extractants.…”