Catalytic delignification of sugarcane bagasse in the presence of acidic ionic liquids

Lignin is one of main components in the most abundant lignocelluloses and is recognized as a unique renewable natural resource for the synthesis of aromatic chemicals. Its isolation and transformation have thereby attracted increasing attention in recent times. Here, an efficient method for the separation of lignin from sugarcane bagasse is reported using acidic ionic liquid catalysts. The structure and physicochemical properties and the molecular weight distribution of the isolated lignin were characterized by FT-IR, 1H NMR and 13C NMR, TG, elemental analysis, UV–vis, SEM and GPC. The results showed that acid functionalized ionic liquids are excellent catalysts for the delignification of sugarcane bagasse: 100% isolation of the desired product was achieved under optimized conditions.

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► Acidic ILs used as catalysts in the delignification of sugarcane bagasse.
► 100% isolation yield of lignin obtained at 200 °C for 30 min.
► Delignification performance depend greatly on the acidic strength of the IL.
► The isolated lignin was characterized by FT-IR, NMR, TG, EA, SEM, UV–vis and GPC.
► 70% degree of liquefaction of isolated lignin achieved in subcritical water.