Liquid Membranes for Efficient Recovery of Phenolic Compounds Such as Vanillin and Catechol

Abstract

Investigations were carried out to obtain different lignin monomers such as vanillin and catechol as efficiently as possible, to prevent side reactions e.g., during lignin degradation. Therefore, extraction experiments were performed to determine the influence of parameters such as initial pH in the aqueous phase, organic phases containing alcohols or solvating extractants, and monomer concentrations. Cyanex 923 (Cy923) and tri-n-butyl-phosphat (TBP) diluted in kerosene were the organic phases chosen to evaluate the transport of vanillin because of their high efficiencies (>76.8%) and suitability in membrane technologies. The most efficient vanillin transport was accomplished with Cy923, as > 90% of vanillin was transferred after 5 h. However, the permeability coefficient at carrier concentration of > 0.48 mol/L was influenced not only by the diffusion but also by the organic mixture viscosity. Thus, this concentration was used in the membrane experiment containing a mixture of vanillin and catechol in the feed phase. Catechol was transported about 7% faster to the receiving phase than vanillin, presumably due to its chemical structure. Side reactions were avoided using the current liquid membrane set-up, allowing the further industrial application of an entire process, which, e.g., recovers vanillin from enzymatic lignin conversion by membrane technology.

Effects of process factors on performances of liquid membrane-based transfer of indole-3-acetic acid

“…An increase in extraction and recovery efficiencies and distribution coefficient with an increase in c L,M 0 and c NaOH,S 0 was reported in the related literature 10 , 11 , 13 , 18 , 25 , 27 , 30 . A higher level of c L,M 0 leads to an increase in the concentration of IAA-L complex in the membrane phase, resulting in enhanced mass transfer of this complex.…”

“…Neutral, acidic (anionic), and basic (cationic) carriers have been extensively used in different applications both on a laboratory and industrial scale 24 . Tri-n-butyl-phosphate ( TBP ) and tri-n-octyl phosphine oxide ( TOPO ) are neutral carriers widely applied to transport organic compounds (e.g., formic, acetic, propionic, butyric, acrylic, levulinic, hippuric, and mandelic acids, vanillin, catechol) and metal ions through liquid membranes 10 , 11 , 24 , 27 . Acidic carriers such as di-(2-ethylhexyl)phosphoric acid ( D 2 EHPA ), bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex 272), and derivatives of Cyanex 272 have been used to extract and transport amino acids, peptides, and metal ions 24 , 28 .…”

Operational Limits of the Bulk Hybrid Liquid Membranes Based on Dispersion Systems

“…Liquid membranes represent a constantly expanding field of research for both analytical and applied separatology, justified by the excellent performance in selectivity [1,2], separation efficiency [3,4] and technical-economic accessibility [5,6]. This is because a liquid membrane is generally any barrier of a liquid nature (homogeneous or heterogeneous, hydrophilic or hydrophobic or emulsified or deposited on supports) interposed between two fluids, with the ability to selectively block the passage from one fluid to another of some or several components [7,8].…”

Three- and Multi-Phase Extraction as a Tool for the Implementation of Liquid Membrane Separation Methods in Practice

“…Liquid membrane separations (bulk [ 1 , 2 , 3 ], supported [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ], emulsion [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ]) combining extraction and stripping processes in a single mass-transfer unit allow the separation of species on their partition between two aqueous phases. Mass transfer occurs through an intermediate organic phase (mass-transfer medium).…”