Microwave-Assisted Sulfonation of Lignin for the Fabrication of a High-Performance Dye Dispersant

Abstract

Designing a valorization approach of lignin is essential to achieve "lignin-first" biorefining, which enables the economic feasibility of the lignocellulosic biorefinery industry. Herein, microwave-assisted sulfonation of lignin was investigated with multiple chemicals for the production of a lignin-based dye dispersant, and the effect of the aliphatic chain of sulfonation reagents on the dispersive performance of the sulfonated lignin was revealed. Structural characterization recommended that 1,4butanesultone exhibited the best reaction activity, and its sulfonation product (SL4) exhibited the highest molecular weight (7190 Da) and sulfonic group content (1.59 mmol•g −1 ) among all samples, because of its long aliphatic chain. The high content of sulfonic group and the high molecular weight of SL4 improved the dispersive performance with excellent high temperature stability in which the dyeing rate was 87.9%. The fiber staining effect evaluation of sulfonated lignin dispersants demonstrated that the etherification by 1,4-butanesultone could reduce the phenolic hydroxyl content of lignin to prevent the adsorption of the dispersant on fiber, limiting the fiber staining by sulfonated lignin during the dyeing process. This highly efficient lignin sulfonation can facilitate the valorization of lignin by fabricating the lignin-based dye dispersant for widespread industrial applications.

Lignin to value-added chemicals and advanced materials: extraction, degradation, and functionalization

“…138 In addition, the properties of sulfonated lignin are related to its sulfonation degree and molecular weight. 139 Some sulfonation reagents with different aliphatic chain lengths were used for the sulfonation of lignin, including 1,4-butanesultone, 1,3-propanesultone, sodium chloroethyl sulfonate and sodium bisulfite. Because 1,4-butanesultone has a long aliphatic chain, sulfonated lignin obtained from 1,4-butanesultone had the highest molecular weight (7190 Da) and content of sulfonate groups (1.59 mmol g −1 ).…”

“…Owing to its high molecular weight and content of sulfonate groups, sulfonated lignin can prevent the agglomeration of dye particles and provide electrostatic repulsion to stabilize and disperse dye particles. 139…”

Recent Studies on the Preparation and Application of Ionic Amphiphilic Lignin: A Comprehensive Review

“…45 Similarly, Xiao et al studied the preparation of a ligninbased dye dispersant using microwave-assisted sulfonated lignin and revealed the effects of the aliphatic chain from the sulfonated reagent on the dispersibility of the sulfonated lignin. 46 Another important field for the applications of amphoteric lignin involves utilizing the structural characteristics of lignosulfonates to prepare new materials and endow them with drug loading and slow-release properties. Beckers et al used interfacial cross-linking in a direct miniemulsion to prepare different lignosulfonates loaded with agrochemicals.…”

“…The experimental portion of this work used an anionic lignin-based polymer as the dispersant, which further promoted the application of lignin in the field of clean coal . Similarly, Xiao et al studied the preparation of a lignin-based dye dispersant using microwave-assisted sulfonated lignin and revealed the effects of the aliphatic chain from the sulfonated reagent on the dispersibility of the sulfonated lignin …”

Isolation and Fractionation of the Tobacco Stalk Lignin for Customized Value-Added Utilization

“…Therefore, lignin is considered to be an excellent raw material to replace petroleum-based polymers to commercial products. For example, it has been used in dispersants ( Xiao et al, 2021 ), biofuels ( Beauchet et al, 2012 ), adhesives ( Ghaffar and Fan, 2014 ), flocculants ( Wang et al, 2020a ), phenolic resins ( Lupoi et al, 2015 ), composite film material ( Wang et al, 2021b ), carbon fibers ( Kadla et al, 2002 ), polyurethane foams ( Cinelli et al, 2013 ), hydrogels and many other fields ( Wang et al, 2020b ; Ma et al, 2021b ). However, most of the research on the preparation of commercial products using lignin is still in the laboratory stage, and a large-scale industrial breakthrough in lignin-based polymer materials has not yet been achieved.…”