COST FP1105 Changes On Lignin Structure Influenced By The Ionic Liquid Raquel Prado a, Xabier Erdocia b, Jalel Labidi b, Tom Welton a Department of chemistry, Imperial College London, London, UK a Chemical and Environmental Engineering Department, University of the Basque Country, San Sebastian, Spain b

COST FP1105 Lignin Lignin properties:  Polyphenol polymer  Aromatics source  50 million tons as residue per year Applications:  Adhesive  Bioactive  Binder  Antioxidant %SoftwoodHardwoodGrasses Coumaryl5 Coniferyl Sinapyl B-O A-O O B B-177 B-B’23 5-5’

COST FP1105 Ionic Liquids Definition  They are salts in the liquid state  Their melting points are lower than 100 °C  Are composed by low symmetry cations and anions Properties  Low melting point  Low vapour pressure  High thermal stability  High chemical stability  High ionic conductivity Applications  Organic synthesis  Solvent and catalyst  Separation processes  Electrochemistry  Tribology  Biorefiner y

COST FP1105 Miscanthus characterization Miscanthus composition Miscanthus is a rapid growth plant %StandardMiscanthus Moisture contentTAPPI T264 cm ±0.03 AshTAPPI T211 om-934.2±0.5 Hot water solubilityTAPPI T207 om ±0.2 NaOH solubilityTAPPI T212 om ±0.7 ExtractivesTAPPI T204 cm-977.9±0.4 LigninTAPPI T222 om ±0.4 Hollocellulose30±2 α-cellulose36.2±0.2

COST FP1105 Experimental conditions Synthesis of [HC 4 im][HSO 4 ]  Drop-wise addition of H 2 SO 4 on butyl imidazole  H 2 SO 4 :butyl imidazole mass ratio 1:1  Magnetically stirred for 24 h and dried under vacuum Synthesis of [Et 3 NH][HSO 4 ]  Drop-wise addition of H 2 SO 4 5 M on triethylamine  H 2 SO 4 : triethylamine mass ratio 1:1  Magnetically stirred for 24 h and dried under vacuum

COST FP1105 Experimental conditions Pretreatment  Miscanthus, water and IL ([Et 3 NH][HSO 4 ] or [HC 4 im][HSO 4 ]) were homogeneously mixed in a 1:2:8 mass ratio.  The mixtures were subjected to different pretreatment times at 120 °C (8 h and 22 h). Lignin precipitation  2 volumes of water were added to black liquor  It was centrifuged at 4000 rpm during 15 min  Washed with distilled water and dried at 70 ºC during 16 h IL + H2O + Miscanthus Black liquor Lignin IL H2O Pulp

COST FP1105 Yields results Pretreatment Sample Solved biomass (%) Lignin (%)S/G ILTime [HC 4 im][HSO 4 ] 8 hIm 8 60 ± ± hIm ± ± [Et 3 NH][HSO 4 ] 8 hAm ± hAm ± ±  [HC 4 im][HSO 4 ] was more active on biomass solubility and lignin extraction than [Et 3 NH][HSO 4 ].  IL affect to S/G ratio:  [HC 4 im][HSO 4 ] leads to higher amount of syringyl units.  [Et 3 NH][HSO 4 ] leads to higher amount of guaiacyl and in both with the pretreatment time syringyl units decreased.

COST FP1105 ATR-IR Characterization [HC 4 im][HSO 4 ]: at 2874 and 3143 cm -1 appeared peaks assigned to stretching on imidazole ring due to IL contamination. [Et 3 NH][HSO 4 ]: at 1268 and 1326 cm -1 appeared bands related with guaiacyl ring stretching and deformation.

COST FP1105 Py-GCMS characterization Butyl imidazole SugarsPhenolicsFatty acids  [HC 4 im][HSO 4 ]: There was butyl imidazole contamination and higher proportion of sugar.  [Et 3 NH][HSO 4 ]: Fatty acid proportion was higher and there was no IL contamination.

COST FP1105 HPSEC Characterization SampleMWMnPolydispersity Im 8 6, Im 22 14, Am 8 36, Am 22 10,  [HC 4 im][HSO 4 ]: Mw increased with the pretreatment time, but polydispersity decreased.  [Et 3 NH][HSO 4 ]: Mw and polydispersity decreased with the pretreatment time.

COST FP1105 Conclusion  [HC 4 im][HSO 4 ] showed higher reactivity. But the obtained lignin was contaminated by imidazole ring.  S/G ratio was also affected by the IL, as it was observed by ATR-IR and py-GCMS:  [HC 4 im][HSO 4 ] lignin had higher amount of syringyl.  [Et 3 NH][HSO 4 ] lignin had higher amount of guaiacyl.  Lignin structure was affected by the IL.

COST FP1105 THANK YOU FOR YOUR ATTENTION