Delignification as a Key Strategy for Advanced Wood-Based Materials: Chemistry, Delignification Parameters, and Emerging Applications

Wood is a naturally abundant, biodegradable, and renewable material with significant potential as an alternative to petroleum-based materials. However, its inherent heterogeneity, anisotropy, and modest mechanical properties limit its application in high-performance structural uses. Delignification, a critical process in papermaking and biorefining, has emerged as a promising pretreatment technique to enhance the properties of wood for advanced subsequent applications. This process selectively removes lignin while preserving the aligned cellulose structure, thereby improving mechanical strength, dimensional stability, and potential for functionalization. Various delignification methods, including alkaline, acidic, and reductive catalytic fractionation, have been explored to optimize the wood’s structural and chemical properties. When combined with densification or impregnation, delignified wood exhibits superior mechanical performance, making it suitable for a range of applications, including structural materials, optical devices, biomedical applications, and energy storage. This detailed review examines the chemistry and mechanisms of delignification, its impact on the physical and mechanical properties of wood, and its role in developing sustainable, high-performance bio-based materials. Furthermore, challenges and future opportunities in delignification research are discussed, highlighting its potential for next-generation wood-based innovative applications.