Highly efficient cellulose dissolution by alkaline ionic liquids

Kallidanthiyil Chellappan Lethesh; Sigvart Evjen; Vishwesh Venkatraman; Syed Nasir Shah; Anne Fiksdahl

doi:10.1016/j.carbpol.2019.115594

Highly efficient cellulose dissolution by alkaline ionic liquids

Carbohydr Polym. 2020 Feb 1:229:115594. doi: 10.1016/j.carbpol.2019.115594. Epub 2019 Nov 11.

Authors

Kallidanthiyil Chellappan Lethesh¹, Sigvart Evjen², Vishwesh Venkatraman², Syed Nasir Shah³, Anne Fiksdahl⁴

Affiliations

¹ Department of chemistry, Norwegian University of Science and Technology (NTNU), 7491-Trondheim, Norway. Electronic address: lethesh.k.chellappan@ntnu.no.
² Department of chemistry, Norwegian University of Science and Technology (NTNU), 7491-Trondheim, Norway.
³ Department of Energy Engineering, University of Engineering and Technology, Taxila, 47080 Rawalpindi, Pakistan.
⁴ Department of chemistry, Norwegian University of Science and Technology (NTNU), 7491-Trondheim, Norway; Department of Energy Engineering, University of Engineering and Technology, Taxila, 47080 Rawalpindi, Pakistan.

PMID: 31826468
DOI: 10.1016/j.carbpol.2019.115594

Abstract

Alkaline ionic liquids (ILs) with unconventional organic anions were prepared and used for cellulose dissolution studies. High concentrations of cellulose were dissolved at room temperature in the phenolate based imidazolium IL [C₂mim][OPh], combined with organic solvent, and up to 45 wt-% cellulose dissolution (wt-% MCC of weight IL) was readily achieved at 100 ºC. No functionalization of the regenerated cellulose was observed during the dissolution process (FTIR). Characteristic cellulose II XRD diffraction pattern was observed after IL dissolution and regeneration of MCC. The crystallinity index (CI) of the pretreated MCC was reduced from 93.2 % to 31 %. Inert conditions were not required for the cellulose dissolution experiments. This study indicates that the IL H-bond basicity is not the only key parameter determining their cellulose dissolution ability. The alkaline ILs represent an energy efficient and sustainable approach for cellulose dissolution.

Keywords: Cellulose dissolution; High concentration; Ionic liquid; Phenolate anion; Room temperature.