Biomass fractionation techniques impact on the structure and antioxidant properties of isolated lignins

Abstract

Lignin is a phenolic residue from biomass refinery industries. Biomass fractionation techniques keep emerging because of the pursuit of improved revenues from biomass refineries, which generates lignin structurally different from conventional one, i.e., the kraft lignin. To understand the impact of emerging biomass fractionation processes on the antioxidant properties of lignin, six lignins were isolated from pine wood, and structurally analyzed with ultraviolet/visible spectroscopy, Fourier transform infrared spectroscopy, hetereonuclear single quantum coherence nuclear magnetic resonance, 31P nuclear magnetic resonance, and gel permeation chromatography. The antioxidant activity of isolated lignins was determined by DPPH assay, ABTS assay, superoxide anion radical scavenging assay, and hydroxyl radical scavenging assay. The structure and antioxidant properties of lignin were discussed accordingly. The results of this study would provide solid data guiding the isolation of lignin-based high-performance antioxidants from biomass.