Extraction and Purification of Phenolic Compounds from Lignocellulosic Biomass Assisted by Ionic Liquid, Polymeric Resins, and Supercritical CO2

A sustainable process of valorization of lignocellulosic biomass exploring the extraction and separation of high value phenolic compounds was developed. A scale-up pretreatment and fractionation process of biomass assisted by 1-ethyl-3-methylimidazolium acetate ([emim][OAc]) ionic liquid (IL) was carried out at first. Thereafter, recovered IL formed a sample rich in phenolic compounds, which separation and purification was the main objective of the present work. The phenolic extraction from the recycled IL was studied employing adsorption methodology with specific polymeric resins. Amberlite XAD-7 and Silica C18 resins showed the highest extraction efficiency of phenolic compounds, while PVPP presented high selectivity toward tricin and a specific lignin fragment. Among the examined resins, Amberlite XAD-7 demonstrated the highest ratio of phenolic compounds extraction in comparison to IL. A residual quantity of IL was observed to remain in the extracted samples and this was overcome by applying supercritical CO2 extraction approach. Proposed methodology allowed to produce high purity main biomass fractions with IL-free extract of phenolic compounds in a green and more sustainable fashion with IL and CO2 processes employed.