Revisiting lignin: a tour through its structural features, characterization methods and applications

Abstract

Lignin is a complex organic polymer found in the plant cell wall with important biological functions, such as water transport, mechanical support, and resistance to various stresses. It is considered...

Thermogravimetric Analysis Properties of Cellulosic Natural Fiber Polymer Composites: A Review on Influence of Chemical Treatments

“…Hemicellulose thermal degradation occurs before cellulose, but its content in the fiber proportionally limits its effect. Lignin is a complex hydrocarbon polymer with both aliphatic and aromatic constituents [ 67 , 69 , 70 ]. The thermal decomposition of lignin occurs in a broader range that initiates earlier but extends to higher temperatures than those of hemicellulose and cellulose degradation [ 71 ].…”

Enzymatic Oxidation of Ca-Lignosulfonate and Kraft Lignin in Different Lignin-Laccase-Mediator-Systems and MDF Production

“…Lignin is one of the three main components of lignocellulosic biomass. It is considered as a pressure-tight amorphous matrix that reinforces and protects as a physical barrier the cellulose microfibril structure of lignified cell walls in vascular plants (Melro et al, 2021). In pulp and paper production, lignin is however an impurity that has to be removed from wooden fiber cells in various steps in order to obtain a pure cellulosic white paper (Smook, 2002).…”

“…In pulp and paper production, lignin is however an impurity that has to be removed from wooden fiber cells in various steps in order to obtain a pure cellulosic white paper (Smook, 2002). With a worldwide annual production of ∼70 Mio t in the pulping liquor, lignin is thus a technical mass byproduct from the pulping industry, for which there is hardly any meaningful commercial use (Vishtal and Kraslawski, 2011;Wenger et al, 2020;Melro et al, 2021). Such technical lignins differ from the lignin in its native form.…”

“…The strong alkali concentration (13%-16%) and the heating to 140-170 °C to break non-phenolic β-O-4 bonds and form phenols also impair the cellulose and lead to an overall inferior-quality pulp. Furthermore, sulfur-free technical lignins with low molecular weight (MW) and higher homogeneity are obtained from organosolv pulping of lignocellulosic biomass as by-products of the second generation of bioethanol production (Ekielski and Mishra, 2021;Melro et al, 2021).…”

“…So far, only about 2% of technical lignins, mainly lignosulfonates (1.8 Mio t/year), are purified for commercial use. The remaining lignin is combusted for energy purposes or not used at all (Mohan et al, 2006;Wenger et al, 2020;Melro et al, 2021). Lignosulfonates were so far mainly used as additives in concrete in the building sector.…”