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

Abstract

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.

Continuous Separation and Purification of Chemical Species by Continuous Liquid–Liquid Partition Chromatography Implemented with Membrane-Based Phase Separators

“…However, this purity is less than expected, as well. It has been previously noted that separation by CPC should be possible for solvent systems with Δlog­( K D ) > 0.2; , in the case of the system used by Carreira et al, the Δlog­( K D ) was approximately 0.40, indicating that this separation should be achievable by CPC. These discrepancies in the performance for both sets of experiments may be able to be attributed to the formation of the tertiary complex which is responsible for the enantioselection of the propranolol enantiomers.…”

Potential of catalytic oxidation of kraft black liquor for the production of biosourced compounds

“…Centrifugal partition chromatography has shown a great potential for separating different phenolic compouds. 46 These technologies could be adapted to recover vanillin from the KBL oxidation product mixture, with additional difficulties caused by the high concentration of sulphur and salts.…”

Bio-based platform chemicals synthesized from lignin biorefinery

“…Distillation separation and chromatographic separation are also used for product separation. [258][259][260][261] In terms of petroleum refineries, it is proper to use distillation because most compounds are volatile. Conversely, the chemicals derived from the biomass are considered non-volatile, and the solution is typically diluted (required for water evaporation).…”