RT Journal Article T1 Protic, Aprotic, and Choline-Derived Ionic Liquids: Toward Enhancing the Accessibility of Hardwood and Softwood A1 Rigual Hernández, Victoria De Los Ángeles A1 Ovejero Pérez, Antonio A1 Rivas Siota, Sandra A1 Domínguez, Juan A1 Alonso Rubio, María Virginia A1 Oliet Pala, María Mercedes A1 Rodriguez, Francisco AB A side-by-side comparison of softwood (pine) vs hardwood (eucalyptus) pretreatment using 3 protic, 3 aprotic, and 3 choline-derived ionic liquids (ILs) is proposed. While the protic ionic liquid 2-hydroxyethylammonium formate leads to alkali lignin dissolution at 30 °C after 1 h, the lack of interactions with the whole-cell wall limits the biomass disruption. On the contrary, the protic ionic liquid 1-methylimidazolium chloride produces a catalytic effect that extracts almost all of the hemicelluloses, and partially the lignin. Remarkable digestibilities are obtained with choline acetate ([Ch][OAc]) in eucalyptus (69%), while in pine, protic, and choline-derived ILs tested do not appear to be real “greener” alternatives to conventional ILs such as 1-ethyl-3- methylimidazolium acetate (the highest digestibility, 84%). Solid morphology revealed a smoother surface in pine pretreated with [Mim][Cl], and confocal fluorescence microscopy was used to distinguish surface holocellulose and lignin, highlighting differences in the accessibility of hardwood vs softwood due to the presence of surface lignin. Two-dimensional nuclear magnetic resonance spectroscopy of saccharified samples pretreated with [Ch][OAc] showed the presence of groups derived from acetate. Finally, thermogravimetric analysis and spectroscopy techniques reveal the difficulties in recovering the ionic liquid and conclude a work that describes the strengths and weaknesses of the ILs and biomasses studied. SN 2168-0485 YR 2020 FD 2020 LK https://hdl.handle.net/20.500.14352/98318 UL https://hdl.handle.net/20.500.14352/98318 LA eng NO Victoria Rigual, Antonio Ovejero-Pérez, Sandra Rivas, Juan C. Domínguez, M. Virginia Alonso, Mercedes Oliet, and Francisco RodriguezACS Sustainable Chemistry & Engineering 2020 8 (3), 1362-1370DOI: 10.1021/acssuschemeng.9b04443 NO Ministerio de Economía y Competitividad (España) DS Docta Complutense RD 12 ago 2024