Lignin extraction, biodegradation and usage

Atiwesh, Ghada (2022) Lignin extraction, biodegradation and usage. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

Lignin is a complex biopolymer abundantly found in all vascular plants. It plays a key role in building connective tissues and giving them strength, rigidity, and resistance to environmental factors such as pathogens. Extracted lignin finds diverse applications in the commercial sector with immense potential in novel value-added applications. Therefore, it is important to develop optimum and sustainable processes for lignin extraction. To this end, one of the aims of the present research was to examine different lignin extraction methods on common wood species present in Newfoundland, Canada – balsam fir, pine, spruce (softwood), birch, maple, and oak (hardwood). Two different lignin extraction methods were studied: (1) the Formacell method, which uses acetic acid/formic acid/water; and (2) the BioEB method, which uses only formic acid/water. Various parameters were tested, including solvent concentration, temperature, cooking time, to determine the most optimal lignin extraction conditions. The results of this study can be applied to inform and improve industrial lignin extraction processes to obtain better yields in the most optimal manner. This thesis also discusses the latest developments in value-added uses of extracted lignin for the preparation of novel bio-based materials. Lastly, it provides a review of the mechanisms of microbial biodegradation of lignin. These microbial ligninolytic mechanisms provide a host of possibilities to overcome the challenges of using harmful chemicals to degrade lignin biowaste in many industries.

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