Interplay of acid-base ratio and recycling on the pretreatment performance of the protic ionic liquid monoethanolammonium acetate

File Description SizeFormat 
Revised Manuscript (ACS SCE) - Final version with DOIs.docxAccepted version187.12 kBMicrosoft WordView/Open
Title: Interplay of acid-base ratio and recycling on the pretreatment performance of the protic ionic liquid monoethanolammonium acetate
Authors: Nakasu, PYS
Clarke, CJ
Rabelo, SC
Costa, AC
Brandt-Talbot, A
Hallett, JP
Item Type: Journal Article
Abstract: The use of protic ammonium ionic liquids (PILs) in the pretreatment of lignocellulosic biomass is a promising alternative to using expensive aprotic ionic liquids such as 1-ethyl-3-methylimidazolium acetate, [Emim][OAc]. In this work, the PIL monoethanolammonium acetate, [MEA][OAc], was used for the pretreatment of sugar cane bagasse. The study investigated changing the acid base ratio (ABR) from 0.1 to 10 and recycling of the solvent. We determined the lignin extraction, lignin recovery, solvent recovery, and enzymatic saccharification yield and compared the performance to that of the pure amine base, monoethanolamine. We found that lignin extraction and glucose release during enzymatic saccharification increased with base (amine) content, reaching up to 84% and 96%, respectively, after 72 h of saccharification for the 0.1 ABR. Up to 97% of the solvent was recovered for the 1.0 ABR. A higher acid content led to increased hemicellulose extraction into the liquid phase and reduced ionic liquid recovery. A partial conversion of the PIL into N-(hydroxyethyl) acetamide was observed after pretreatment, with up to 86% of conversion after the sixth use for the 1.0 ABR. A negative correlation (R2 = 0.96) was found between the acetamide content in the solvent and the saccharification yield. The drop in pretreatment performance was also correlated with a decrease in accumulated lignin recovery and the molecular weight of the isolated lignins. Acetamide formation was reduced when excess base was present. Recycling of the mixture with 0.5 ABR showed that the performance was unchanged (97% saccharification yield) after three uses, although 28% of the mixture was converted into the acetamide. The study shows that protic acetate ILs made from primary amines form an equilibrium with their amide and a low ABR is required in order to maintain high pretreatment efficiency when the PIL is reused.
Issue Date: 1-Jun-2020
Date of Acceptance: 1-Apr-2020
URI: http://hdl.handle.net/10044/1/82495
DOI: 10.1021/acssuschemeng.0c01311
ISSN: 2168-0485
Publisher: American Chemical Society
Start Page: 7952
End Page: 7961
Journal / Book Title: ACS Sustainable Chemistry and Engineering
Volume: 8
Issue: 21
Copyright Statement: © 2020 American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Sustainable Chemistry and Engineering, after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acssuschemeng.0c01311
Keywords: Science & Technology
Physical Sciences
Technology
Chemistry, Multidisciplinary
Green & Sustainable Science & Technology
Engineering, Chemical
Chemistry
Science & Technology - Other Topics
Engineering
Protic ionic liquid
Pretreatment
Sugar cane bagasse
Acid base ratio
Solvent recycling
SUGARCANE BAGASSE
ACETIC-ACID
LIGNOCELLULOSIC BIOMASS
ENZYMATIC-HYDROLYSIS
LIGNIN
SACCHARIFICATION
CELLULOSE
AMMONIA
DIGESTIBILITY
FERMENTATION
Science & Technology
Physical Sciences
Technology
Chemistry, Multidisciplinary
Green & Sustainable Science & Technology
Engineering, Chemical
Chemistry
Science & Technology - Other Topics
Engineering
Protic ionic liquid
Pretreatment
Sugar cane bagasse
Acid base ratio
Solvent recycling
SUGARCANE BAGASSE
ACETIC-ACID
LIGNOCELLULOSIC BIOMASS
ENZYMATIC-HYDROLYSIS
LIGNIN
SACCHARIFICATION
CELLULOSE
AMMONIA
DIGESTIBILITY
FERMENTATION
0301 Analytical Chemistry
0502 Environmental Science and Management
0904 Chemical Engineering
Publication Status: Published
Online Publication Date: 2020-04-27
Appears in Collections:Chemistry
Chemical Engineering
Faculty of Natural Sciences