Lignin is one of the three major components of the cell wall of lignocellulosic biomaterials. It is the second-most abundant polymer in nature. It is a complex and heterogeneous polymer found in the cell walls of lignocellulosic biomass. Lignin’s predominant composition, which is rich in carbon and aromatic structures, enhances its value by enabling the development of high-value chemicals and bio-based materials. As one of the most affluent natural renewable sources of aromatic structures and the world’s second-largest renewable source of carbon, lignin possesses a thermal value comparable to that of carbon. Its aromatic constituents exhibit unique chemical properties and significant bioactive effects, making lignin a crucial material in various advanced applications. Different chemical fractionation methods have been designed to overcome the obstacles to extracting the lignin biopolymer from lignocellulosic biomass. Lignin fractionation is a process that involves separating lignin from other components of biomass feedstock, such as cellulose and hemicellulose. This process is commonly used in the paper and pulp industry to obtain valuable lignin derivatives that can be used in various applications, including, among others, biofuels, chemicals, and biomaterials. In the brief overview described in this proceedings paper, we provide a comprehensive chemical overview of the current processes for extracting technical lignin from wood and lignocellulosic biomass, critically evaluating the advantages and limitations of each method.

This study, in the form of a patent evaluation, which is a technique for studying the information present within and attached to patents, describes the state of the art by introducing what has been patented in relation to softwood lignin derivatives. Inventors have described and claimed, through the US9347177B2 patent, a method for the preparation of derivatives of native lignin from softwood sources that have a certain aliphatic hydroxyl content. The invention covered by the patent concerns the processes of treating or compounding macromolecular substances and compositions of lignin-containing materials, as well as lignin and products derived therefrom. To prove the concept of this invention, recovery of lignin derivatives has been carried out from three softwood species. Samples of each softwood biomass feedstock were treated using an acid-catalyzed ethanol organosolv pulping process under different conditions. As a result, the recovered lignin derivatives may have an aliphatic hydroxyl content of 2.5−7 mmol.g⁻¹, a phenolic hydroxyl content of 2−8 mmol.g⁻¹, a molecular weight that varies in the range of 200−4000 g.mol⁻¹, and any suitable polydispersity of 1−5. These features result in a product with more consistent antioxidant activity. Furthermore, these recovered lignin derivatives may be advantageous when formulating such compositions, making these materials highly desired for wide applications.