Green and sustainable pretreatment methods for cellulose extraction from lignocellulosic biomass and its applications: A review

Lignocellulose biomass (LCB) is a plant biomass mainly composed of cellulose, hemicellulose, and lignin. Cellulose is the most abundant biodegradable polymer on Earth and is very useful for various applications. However, the complex structure of lignocellulosic biomass, in which cellulose is tightly bound to hemicellulose and lignin, poses significant challenges in the isolation of cellulose from LCB components. This necessitates efficient pretreatment techniques to enable cellulose separation. Conventional pretreatment methods are not sustainable because they involve the use of harsh chemicals, elevated temperatures, high energy consumption, low productivity, and the formation of fermentation inhibitors which can increase the cost of biomass processing with negative environmental impacts. Green pretreatment methods have been proposed to address these issues using milder and more sustainable approaches. These green methods are evaluated in terms of their delignification efficiency, reduced solvent requirement, environmental impact, economic viability, and relevance to recent advancements in sustainable pretreatment technologies. This review provides overview of the application of green and environmentally friendly methods in the isolation of cellulose from various lignocellulosic biomass, as well as the potential of cellulose as a key feedstock in the bioeconomy by showcasing cellulose versatility in various industrial applications.