Laccase, an Emerging Tool to Fabricate Green Composites: A Review

Abstract

In the last two decades, laccases have received much attention from researchers because of their specific ability to oxidize lignin. This function of laccase is very useful for applications in several biotechnological processes, including delignification in the pulp and paper industry and the detoxification of industrial effluents from the textile and petrochemical industries. This review focuses on laccase-mediated fiberboard synthesis. Growing concerns regarding the emission of formaldehyde from wood composites has prompted industrialists to consider the fabrication of green composites. Laccase-mediated fiber treatments oxidize the lignin component without affecting the cellulose structure. As a result, free radicals are generated on the fiber surface, and these can act as potential reactive sites for further cross-linking reactions in board manufacturing. Binderless fiberboards prepared using such methods can be considered as green composites because the manufacturing process involves no additional resin.

Characterisation of Laccase Modified Mukwa (Pterocarpus Angolensis) Wood Flour

“…The spectrum of untreated and laccase treated wood flours are almost similar whereas NaOH pretreatment shown a significant improvement. Strong broad bands of 3% and 5% NaOH pretreated at 3341 and 3334 cm -1 respectively can be attributed to aromatic and aliphatic OH functional groups [18]. From Fig.…”

“…This can be credited to a fact that none of the treatments (on their own) can impart desired qualities, as fibre cleaning was not fully achieved. A review made by [18] found that laccase treatment improved inter bonding strength of fibres in numerous ways like surface smoothness/roughness that encourages mechanical interlocking between fibres Fig 1c, suggesting that a combination of laccase and higher concentration of NaOH is more effective in refining fibre surface. Enzymatic treatment resulted in more defined structures as more non-cellulosic materials and surface impurities were extracted.…”

“…It is thought that mercerisation increasing the overall crystallinity index thereby improving the order of crystallites and thickening cell walls upon treatment [26]. Laccase oxidizes lignin without affecting the structure of cellulose [18]. Therefore, it can be deduced that both mercerisation and laccase treatment improve crystallites packing order rather than increasing crystallinity index.…”

“…Laccase is an oxidoredactase enzyme known for modfiying lignin structure as well on its constituent compounds (phenols, polyphenols, methoxy-substituted phenols, anilines, hydroxyindols, aryldiamines and benzenethiols. It aids in either the chemical or physcial bonding of fibres by generating free radicals [18]. Mamum & Bledzki (2013) [16] analysed the effect of lacasse treatment on natural fiber.…”

The Effect of Laccase Pretreatment Conditions on the Mechanical Properties of Binderless Fiberboards with Wheat Straw

“…Non-resin wheat straw fiberboards have been manufactured from fibers that were pretreated with Fenton reagent (Halvarsson et al 2009). The laccase pretreatment process is a reliable method for selfbonding technology (Nasir et al 2015;Zhang et al 2015). Using laccase-treated wheat straw fibers in the production of binderless fiberboards has not yet been reported.…”