A review on the principles and mechanism of chemical, biological and mechanical treatments during nanocellulose extraction

Abstract Lignocellulosic biomass is a complex biopolymer that is mainly composed of hemicellulose, cellulose, and lignin. Cellulose is the major component of lignocellulosic biomass, and it can be extracted and depolymerized into nanocellulose with excellent properties. Due to the abundance, biocompatibility, biodegradability, high purity, high mechanical strength, and non-toxic properties numerous studies has been reported on the extraction of nanocellulose from various lignocellulosic biomass sources. The nanocellulose can be extracted using various chemical, mechanical and biological treatment methods. Acid hydrolysis is a conventional extraction method but it utilizes harsh chemicals and raise environmental concern. Alternative sustainable techniques such as enzymatic hydrolysis, high pressure homogenization, ultrasonication, ball milling, solvent systems like deep eutectic solvents (DES) and ionic liquids (IL) are gaining interest. They provide increased control over nanocellulose characteristics while lowering environmental impacts. This review summarizes the processing parameters, mechanisms, benefits, disadvantages of these methods. This review also offers key insights on how to optimize extraction techniques to achieve scalable and eco-friendly nanocellulose extraction.