Studying the effects of laccase-catalysed grafting of ferulic acid on sisal pulp fibers

Functionalization of sisal specialty pulp fibers by laccase-catalysed grafting of ferulic acid (FRC) was investigated. To this end, the extent of phenol coupling to fibers under different reaction conditions (laccase and FRC rates, and time) was evaluated in terms of pulp properties including kappa number (expressed as the combined contributions of lignin and hexenuronic acids), brightness, Klason lignin and surface anionic charge after Soxhlet extraction of acetone-treated pulp. The specific treatment resulting in the highest degree of grafting was then used in a comparative study of the effects of applying the laccase–FRC system to refined and unrefined pulp with a view to confirming whether the increased surface area obtained by effect of fibrillation would lead to enhanced grafting. Based on the results, refining the pulp prior to the enzyme treatment resulted in increased grafting which in turn led to handsheets with improved strength-related properties (particularly wet tensile strength) relative to control samples.

► We study functionalization of sisal pulp fibers by laccase-catalyzed grafting of ferulic acid.
► We evaluate the extent of grafting under variable reaction conditions via pulp properties.
► A comparative study of the effects of applying grafting to refined and unrefined pulp is performed.
► Refining the pulp prior to the enzyme treatment resulted in enhanced grafting.
► A higher degree of grafting led to handsheets with improved strength properties.