Assessing cellulose dissolution efficiency in solvent systems based on a robust experimental quantification protocol and enthalpy data

Author(s)

Kostag, Marc ^[1] ; Dignani, Marcella Teixeira ^[1] ; Lourenco, Matheus Costa ^[1] ; Bioni, Thais de Almeida ^[1] ; El Seoud, Omar A. ^[1]

Affiliation

^[1] Univ Sao Paulo, Inst Chem, Ave Prof Lineu Prestes 748, BR-05508000 Sao Paulo, SP - Brazil

• Document type: Journal article
• Source: HOLZFORSCHUNG; v. 73, n. 12, p. 1103-1112, DEC 2019.
• Web of Science Citations: 3

Abstract

Dissolution of microcrystalline cellulose (MCC) in pure ionic liquids (ILs) and IL/dimethyl sulfoxide (DMSO) mixtures (mole fraction chi(DMSO) =0.2-0.9) was quantified using a specially constructed mechanical stirring system that allows reproducible agitation speed; temperature control, and minimum solution-air contact. The electrolytes employed were: 1-(n-butyl)-3-methylimidazolium acetate (C(4)MeIm AcO), 1-(methoxyethyl)-3-methylimidazolium acetate (C(3)OMeIm AcO), 1,8-diazabicyclo{[}5.4.0] undec-7-enium acetate (DBU AcO), tetramethylguanidinium acetate (TMG AcO), and tetra(n-butyl)ammonium fluoride hydrate (TBAF center dot xH(2)O). The effects on MCC dissolution of IL/DMSO composition, and temperature (50, 70 degrees C) were studied. C(4)MeIm AcO and C(4)MeIm AcO/DMSO were more efficient solvents than their C(3)OMeIm AcO counterparts, due to ``deactivation{''} of the ether oxygen of C(3)OMeIm AcO. MCC dissolution by C(4)MeIm AcO/DMSO was compared with DBU AcO/DMSO, TMG AcO/DMSO at chi(DMSO) =0.6, and TBAF center dot xH(2)O/DMSO at chi(DMSO) = 095. The relative efficiency was (solutions in DMSO): C(4)MeIm AcO > C(3)OMeIm AcO > DBU AcO > TMG AcO > TBAF center dot xH(2)O. The efficiency of C(4)MeIm AcO relative to C(3)OMeIm AcO is due to higher solution basicity. Isothermal titration calorimetry was used to study cellobiose-solvent interactions. Except for TBAF center dot xH(2)O/DMSO, these interactions are exothermic; the relative solvent efficiency increases with increasing dissolution vertical bar enthalpy vertical bar. Using the mole fraction concentration scale to report cellulose dissolution avoids possible ambiguities. (AU)

• FAPESP's process: 17/06394-1 - Muti-user equipment approved in grant 2014/22136-4: isothermal titration calorimeter (ITC) for the determination of thermodynamic parameters of molecular interactions
• Grantee: Omar Abou El Seoud
• Support Opportunities: Multi-user Equipment Program
• FAPESP's process: 14/22136-4 - Use of green solvents and their mixtures for optimizing chemical processes
• Grantee: Omar Abou El Seoud
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 16/22869-7 - Novel solvents in cellulose chemistry: synthesis, properties, and application of quaternaryammonium electrolytes for dissolution, regeneration, and derivatization of cellulose
• Grantee: Marc Kostag
• Support Opportunities: Scholarships in Brazil - Post-Doctoral