Miscanthus x giganteus Bark Organosolv Fractionation: Fate of Lipophilic Components and Formation of Valuable Phenolic Byproducts

The behavior of Miscanthus x giganteus bark lipophilic extractives during three acid organosolv pulping processes (Acetosolv, formic acid fractionation, and Milox) was investigated. It was demonstrated that nearly 90% of the lipophilic extractives were removed from pulps by either dissolution in the organosolv liquors (fatty acids and alcohols) or extensive degradation (sterols). The organosolv liquors were found to be rich in vanillin, syringaldehyde, and ferulic, vanillic, and p-coumaric acids. The Acetosolv fractionation process was found to be the most efficient in the removal of lipophilic components from pulps, and it was also the process that generated higher amounts of valuable monomeric phenolic compounds that could be exploited within the biorefinery context.