Dissolution and Hydrolysis of Bleached Kraft Pulp Using Ionic Liquids

• Published in: Polymers Vol. 11; no. 4; p. 673
• Main Authors: Reyes, Guillermo, Aguayo, María Graciela, Fernández Pérez, Arturo, Pääkkönen, Timo, Gacitúa, William, Rojas, Orlando J
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 12-04-2019; MDPI
• Subjects: Atomic force microscopy; Bleaching; Cellulose; cellulose dissolution; Chloride; Chlorides; Dissolution; Dynamic models; Eucalyptus; green technology; Hydrogen bonds; Hydrolysis; ionic liquid; Ionic liquids; Kraft pulp; Microscopy; Molecular dynamics; nanocellulose; Nanocrystals; Solvents; Titration; Toxicity; Water chemistry; ionic liquid; nanocellulose; green technology; cellulose dissolution
• ISSN: 2073-4360; 2073-4360
• DOI: 10.3390/polym11040673

Forestry industries in Chile are facing an important challenge-diversifying their products using green technologies. In this study, the potential use of Ionic Liquids (ILs) to dissolve and hydrolyze eucalyptus wood (mix of
and
) kraft pulp was studied. The Bleached Hardwood Kraft Pulp (BHKP) from a Chilean pulp mill was used together with five different ILs: 1-butyl-3-methylimidazolium chloride [bmim][Cl], 1-butyl-3-methylimidazolium acetate [bmim][Ac], 1-butyl-3-methylimidazolium hydrogen sulfate [bmim][HSO
], 1-ethyl-3-methylimidazolium chloride [emim][Cl], 1-ethyl-3-methylimidazolium acetate [emim][Ac]. Experimentally, one vacuum reactor was designed to study the dissolution/hydrolysis process for each ILs; particularly, the cellulose dissolution process using [bmim][Cl] was studied proposing one molecular dynamic model. Experimental characterization using Atomic Force Microscopy, conductometric titration, among other techniques suggest that all ILs are capable of cellulose dissolution at different levels; in some cases, the dissolution evolved to partial hydrolysis appearing cellulose nanocrystals (CNC) in the form of spherical aggregates with a diameter of 40-120 nm. Molecular dynamics simulations showed that the [bmim][Cl] anions tend to interact actively with cellulose sites and water molecules in the dissolution process. The results showed the potential of some ILs to dissolve/hydrolyze the cellulose from Chilean Eucalyptus, maintaining reactive forms.