From Black Liquor to Green Material: Enzymatic Valorization of Pulp Industry Byproducts

Kraft lignin (byproduct of the Kraft cooking process) was isolated from the black liquor to study and optimize the experimental conditions for its enzymatic polymerization. Lignin polymerization was used as binder in the manufacture of medium density fiberboards (MDF) with no synthetic adhesives. The objective of this study was to produce MDF totally free of adhesives, where wood fibers were bonded together due solely to the bonds created by enzymatic polymerization of the lignin in the fibers. The addition of Kraft lignin to the wood fibers before the MDF manufacture significantly improved the mechanical and dimensional properties of the board. Some of the produced pilot-scale MDF have properties that meet the standards to be marketed. In this way, a completely free MDF synthetic adhesives were obtained valuing simultaneously a byproduct from the pulp industry available worldwide on a large scale.