Lignin, a complex and abundant biopolymer, is predominantly generated as a by-product from the paper, pulp, and lignocellulosic biomass industries. Despite its availability and promise, lignin’s complicated molecular structure and poor solubility have restricted its economic use. Lignan, which accounts for up to 30% of lignocellulosic biomass, is a sustainable source of aromatic chemicals. However, its inherent stability and intricacy have limited its use. Studies have looked at the development and relationships of lignin’s monolignols and units, as well as its macroscopic physicochemical characteristics. Several methods for synthesis and characterization of lignin have been developed, including spectrometry, chromatography, and spectroscopy. Lignin has been a popular raw material for the synthesis of economically useful chemicals over the last two decades. Despite this, most of the lignin from the pulp business is still utilized as boiler fuel, albeit less efficiently than lignin from the lignocellulosic-based bioethanol sector in terms of manufacturing sustainable polymeric materials. As a result of its properties, lignin is used to manufacture a variety of chemical products, including esters, ethers, bioadhesives, lubricants, foams, nanoparticles, and nanocomposites. Lignin production, particularly from the paper and bioethanol industries, poses a significant threat to the environment. In addition to reducing environmental impacts, converting this surplus lignin into valuable products could boost paper and bioethanol industries’ economic growth.
