Work

Targeted phenolation and rapid extraction of light-colored lignin from pine using nucleophilic reagent in combination with acid hydrotrope p-TsOH

Year: 2025

Type: article

Abstract: Structural change, reduced reactivity, and deepened color of lignin caused by uncontrollable reaction in the process of separation are the main problems that hinder its effective utilization. Based on lignin-first strategy, nucleophilic phenol (PH) or syringol (SL) in conjunction with hydrotrope p -toluenesulfonic acid ( p -TsOH) was employed to separate phenolated and light-colored lignin from pine under mild conditions. It was found that the quick and targeted reaction of the nucleophilic PH or SL with lignin at the sidechain C α position inhibited the cleavage of β-O-4 bonds thus reduced the intermolecular condensation of lignin and the formation of chromophoric groups. The introduction of phenolic hydroxyl groups and low condensation degree enhanced the solubility of lignin in p -TsOH solution, resulting in a high extract yield of lignin. The separated lignin had a lighter color, more phenolic hydroxyl and methoxyl groups, abundant β-O-4 bond and more uniform molecular distribution and exhibited an exceptional UV shielding and antioxidant activity. The phenolated lignins were easily self-assembled into regular spherical nanoparticles by anti-solvent method, which had good mixing effect with face cream to prepare sunscreen with adjustable sun protection factor (SPF) value. • Grafting PH or SL onto lignin inhibited cleavage of β-O-4 and chromophore formation. • Increased phenol -OH and low condensation degree enhanced lignin solubility in p -TsOH. • Phenolation of lignin improved its ultraviolet shielding and antioxidant properties. • Sunscreen with adjustable SPF was prepared using light-colored lignin nanoparticles.

Source: Industrial Crops and Products

DOI: 10.1016/j.indcrop.2025.120965