02365naa a2200289 a 450000100080000000500110000800800410001902200140006002400520007410000230012624501660014926000090031552014760032465000150180065000130181565000110182865000120183965300260185165300190187770000140189670000170191070000200192770000240194770000170197170000160198877300710200421786302026-03-10       2025    bl uuuu     u00u1 u    #d  a2190-68157 ahttps://doi.org/10.1007/s13399-025-06502-y2DOI1 aOLIVEIRA, D. R. de  aUnveiling the mechanistic aspects of different delignification methods and their effects on the structure of technical Eucalyptus lignins.h[electronic resource]  c2025  aThe correct application of lignin is directly related to its structure which is strongly affected by the extraction method. In this work, three technical lignins were obtained from Eucalyptus urograndis by Kraft, fast pyrolysis (FP), and microwave-assisted organosolv delignification (MWAOD), and their structural and antioxidant properties were evaluated and compared to those of milled wood lignin (MWL). The samples were characterized by FTIR, 2D and 31P NMR, GPC, TGA, DSC and DPPH. assay. The technical lignins were obtained with elevated yields (33 – 68.5%) and high purities (76 – 93%). The combination of different analytical techniques showed that the higher the severity the lower the molecular weights (657 – 1959 g mol− 1), the higher the quantity of condensed structures (β-5’ and β-β’), and the higher the concentration of phenolic hydroxyls. During MWAOD process, partial acetylation of aliphatic hydroxyls of organosolv lignin (OL) occurred under mild conditions. The thermal stability and the molecular mobility of lignins were also affected by the nature of the extraction method. The DPPH. assay showed that the structural features of lignins also affected their antioxidant activities, since the IC50 values varied from 13.2 to 19.3 μg mL− 1. Therefore, three technical lignins with different structural features were obtained from the same biomass through distinct processes, offering different possibilities for their valorization.  aEucalyptus  aHardwood  aLignin  aLignina  aEucalyptus urograndis  aMadeira de lei1 aMATOS, M.1 aSILVA, K. T.1 aMAZZETTO, S. E.1 aMAGALHAES, W. L. E.1 aLOMONACO, D.1 aAVELINO, F.  tBiomass Conversion and Biorefinerygv. 15, p. 29175–29189, 2025.