Advanced Fractionation of Kraft Lignin by Aqueous Hydrotropic Solutions

Abstract

Lignin is an underutilized high-potential biopolymer that has been extensively studied over the past few decades. However, lignin still has drawbacks when compared with well-known petroleum-based equivalents, and the production of tailored lignin fractions is highly in demand. In this work, a new method for the fractionation of Lignoboost Kraft Lignin (LKL) is proposed by using two different hydrotropes: sodium xylenesulfonate (SXS) and sodium cumenesulfonate (SCS). The different fractions are obtained by sequentially decreasing the hydrotropic concentration with the addition of water. Four and three different fractions were retrieved from the use of SXS and SCS, respectively. The LKL and respective fractions were analysed, and compared by GPC, FTIR-ATR, 1H-NMR, 13C-NMR, 31P NMR, 2D HSQC and SEM. The fractions showed different molecular weights, polydispersity, and amount of functional groups. Our water-based lignin fractionation platform can potentially be combined with different lignin extraction and processing technologies, with the advantage of hydrotrope recycling.

Lignocellulosic Biomass in Nanopesticides: A Path toward Sustainable Agriculture

“…Sulfonated lignin can exhibit surfactant properties, reducing the water surface tension and increasing the stability of colloidal dispersions. These are essential characteristics in the formulation of detergents, emulsifiers, and dispersants. , …”

“…These are essential characteristics in the formulation of detergents, emulsifiers, and dispersants. 82,83 The sulfonation process can enhance the compatibility of modified lignin with different polymeric matrices, for example, in replacing parts of nonrenewable compounds with the phenolics present in the lignin structure. 40 This imparts mechanical properties similar to or even superior to those of versions with matrices purely comprising nonrenewable sources.…”

Role of Deep Eutectic Solvent Precursors as Hydrotropes: Unveiling Synergism/Antagonism for Enhanced Kraft Lignin Dissolution

“…The effect of water on the dissolution of lignin is equally important and Kumar et al studied the impact of adding water during the extraction of lignin. The authors concluded that the addition of a small amount of water during the delignification of rice straw significantly improved the extraction of lignin, demonstrating that the addition of water contributes to the dissolution of lignin . Soares et al identified that DES aqueous solutions allowed an increase in the solubility of Kraft lignin higher than 1180-fold, and the results suggested the presence of a hydrotropic mechanism behind the solubility of lignin in aqueous solutions of DESs.…”