pH-Responsive Lignin Hydrogel for Lignin Fractionation

Abstract

The efficient strategy for lignin fractionation is of great significance for its valorization into aromatics, fine chemicals, and functional materials. In this work, inspired by the traditional gel filtration and pH-responding solubility of lignin, a pH-responsive lignin-based hydrogel was fabricated via a simple cross-linking reaction and used for specific fractionation of lignin. The fraction with a higher molecular weight, more flexible linkages, aliphatic hydroxyl and carboxyl groups, and a high S/G ratio tends to entangle or aggregate with the network of the hydrogel. The pore size and water absorbency of the hydrogel can be tuned in different pH environments. As the solution switches to an acid environment, the unabsorbed fraction was precipitated completely, while the absorbed fraction was held by the shrunken pores of the hydrogel and then released to the fresh alkaline solution. This new strategy will find a new green and smart pathway for the development of not only the pH-responsive hydrogel but also lignin valorization.

“Deep Eutectic Solvent-in-Water” Hydrogels Enable High-Performance Flexible Strain Sensors for Electronic Skin with a Wide Operating Temperature Range

“…Nevertheless, few attempts have been made in this system for renewable catechol-containing natural polymers, but there is a great need and promise for green preparation and sustainability. Lignin is a natural and the most abundant polyphenolic macromolecular that can trigger dynamic redox reactions with high-valent metal ions, thereby activating peroxide to generate free radicals that enable rapid gelation of gels at ambient temperatures. , Meanwhile, the addition of lignin can impart good mechanical properties, biocompatibility, and ultraviolet (UV) shielding properties to the gels, , which imparts lignin-based hydrogels with attractive sensing applications thereby. In contrast to water-insoluble lignin, sodium lignosulfonate shows excellent solubility in aqueous solutions without a modified reaction, which can be directly added into the hydrogel networks. , The use of aqueous Ls-based macromolecular initiator systems has been paid little attention.…”

Biomass‐Based, Interface Tunable, and Dual‐Responsive Pickering Emulsions for Smart Release of Pesticides

“…[19] Due to its complex and heterogenous structure, lignin conversion to well-defined chemicals is challenging. [20,21] Nevertheless, the aromatic skeleton and multiple functional groups of lignin make the biopolymer holds great potential for preparing functional materials. Lignin has amphiphilic, antioxidant, anti-UV, and antimicrobial properties, enabling it an ideal shell material for protecting sensitive pesticides.…”

Biomass-Based Carbon Nanofibers Modified with Polyaniline for Supercapacitor Applications

“…Compared with the petroleum-based polymer as a precursor, the high value-added conversion of lignin can not only effectively improve the profits of the paper and biorefining industry but also effectively reduce costs and improve the renewability in the CNF field. − However, due to significant differences in the intrinsic chemical structure of lignin compared to that of other petroleum-based materials, the direct introduction of lignin through physical blending often seriously affects material properties during the preparation of high-value materials. Therefore, many strategies have been developed to chemically modify lignin macromolecules to meet the requirements of the corresponding high-value materials. − In our previous study, for the preparation of lignin-based hybrid electrodes, polyaniline segments were grafted onto lignin macromolecules, which could effectively reduce the phase separation between lignin macromolecules and polyaniline segments. The obtained polyaniline-/biomass-based CNFs exhibit the complete fibrous micromorphologies, large specific surface area, and excellent electrochemical energy storage performances .…”