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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Uncovering the potentialities of protic ionic liquids based on alkanolammonium and carboxylate ions and their aqueous solutions as non-derivatizing solvents of Kraft lignin

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Author(s):
Dias, Rafael M. [1, 2] ; da Costa Lopes, Andre M. [2] ; Silvestre, Armando J. D. [2] ; Coutinho, Joao A. P. [2] ; da Costa, Mariana C. [1]
Total Authors: 5
Affiliation:
[1] Univ Campinas UNICAMP, Sch Chem Engn FEQ, DDPP, Ave Albert Einstein 500, BR-13083852 Campinas, SP - Brazil
[2] Univ Aveiro, Dept Chem, CICECO, Aveiro Inst Mat, P-3810193 Aveiro - Portugal
Total Affiliations: 2
Document type: Journal article
Source: INDUSTRIAL CROPS AND PRODUCTS; v. 143, JAN 2020.
Web of Science Citations: 0
Abstract

The present study scrutinized in depth the ability of alkanolammonium-based Protic Ionic Liquids (PILs) with carboxylate anions to dissolve Kraft lignin at 323.15 K. A focus was put on understanding the role of both PIL. ions and water on the dissolution process. The results demonstrated that the anion plays a more important role in lignin dissolution than the cation. Furthermore, lignin dissolution was favored by increasing the alkyl chain of the carboxylate anion, while a smaller cation with lower number of hydroxyalkyl groups performed better. Among the studied solvents, the 2-hydroxyethylarnmonium hexanoate (HEAH) displayed the highest lignin solubility (37 wt%). In general, the addition of water had a negative influence on lignin solubility with the tested PILs. A sharp decrease in lignin solubility curves of 2-hydroxyethylammonium formate (HEAP) and acetate (HEAA) was observed, while a more softly effect was observed for 2-hydroxyethylammonium propionate (HEAP) and HEAH with the addition of water. However, a distinct behavior was observed for 2-hydroxyethylammonium octanoate (HEAD) that acted as hydrotrope enhancing lignin solubility in aqueous solutions to a maximum value at 40 wt% water content. Furthermore, by increasing the temperature, the lignin solubility was favored due to endothermic behavior of lignin dissolution process. The dissolution of Kraft lignin was also performed at 393.15 K to unravel any lignin modification unleashed by PILs. GPC, FTIR-ATR and 2D NMR were employed for lignin characterization and the changes observed between native lignin and recovered lignin samples were negligible demonstrating the non-derivatizing character of the PILs. Moreover, the recycle of 2-hydroxyethylammonium propionate (HEAP) was successfully demonstrated for at least 3 cycles. In this way, PILs are herein revealed as promising solvents to apply in lignin valorization towards more efficient and eco-friendly processes. (AU)

FAPESP's process: 14/21252-0 - Equilibrium and production processes of biofuels and bioproducts
Grantee:Antonio José de Almeida Meirelles
Support Opportunities: Research Projects - Thematic Grants
FAPESP's process: 16/08566-1 - Phase equilibrium thermodynamics for the improvement of physical properties of food bioproducts and their prediction in industrial and digestive processes
Grantee:Guilherme José Maximo
Support Opportunities: Regular Research Grants