Selective Separation of Vanillic Acid from Other Lignin-Derived Monomers Using Centrifugal Partition Chromatography: The Effect of pH


In this work, centrifugal partition chromatography (CPC) assisted by a polyethylene glycol (PEG)/sodium polyacrylate (NaPA) aqueous biphasic system (ABS) was applied in the separation of five lignin-derived monomers (vanillin, vanillic acid, syringaldehyde, acetovanillone, and p-hydroxybenzaldehyde). The influence of the system pH (unbuffered, pH 5, and pH 12) and added electrolytes (inorganic salts or ionic liquids (ILs)) on the compound partition was initially evaluated. The obtained data revealed that ILs induced more adequate partition coefficients (K < 5) than inorganic salts (K > 5) to enable separation performance in CPC, while alkaline conditions (pH 12) demonstrated a positive impact on the partition of vanillic acid. CPC runs, with buffered ABS at pH 12, enabled a selective separation of vanillic acid from other lignin monomers. Under these conditions, a distinct interaction between the top (PEG-rich) and bottom (NaPA-rich) phases of the ABS with the double deprotonated form of vanillic acid is expected when compared to the remaining lignin monomers (single deprotonated). This is an impactful result that shows the pH to be a crucial factor in the separation of lignin monomer compounds by CPC, while only unbuffered systems have been previously studied in the literature. Finally, the recovery of vanillic acid up to 96% purity and further recycling of ABS phase-forming components were approached as a proof of concept through the combination of ultrafiltration and solid-phase extraction steps.




Chemistry; Science & Technology - Other Topics; Engineering


Rocha, ILD; Lopes, AMD; Ventura, SPM; Coutinho, JAP

nossos autores


This work was carried out under the Project inpactus innovative products and technologies from eucalyptus, project no. 21874 funded by Portugal 2020 through the European Regional Development Fund (ERDF) in the frame of COMPETE 2020 no. 246/AXIS II/2017. This work was also developed within the scope of the project CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020, financed by national funds through the Portuguese Foundation for Science and Technology (FCT)/MCTES. A.M.D.C.L. thanks his research contract funded by FCT and project CENTRO-04-3559-FSE-000095 -Centro Portugal Regional Operational Programme (Centro2020), under the PORTUGAL 2020 Partnership Agreement, through the ERDF.

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