Reference : Impact of formic/acetic acid and ammonia pre-treatments on chemical structure and physic...
Scientific journals : Article
Life sciences : Multidisciplinary, general & others
http://hdl.handle.net/2268/97740
Impact of formic/acetic acid and ammonia pre-treatments on chemical structure and physico-chemical properties of Miscanthus x giganteus lignins
English
Vanderghem, Caroline mailto [Université de Liège - ULg > Chimie et bio-industries > Chimie biologique industrielle >]
Richel, Aurore mailto [Université de Liège - ULg > Chimie et bio-industries > Chimie biologique industrielle >]
Jacquet, Nicolas mailto [Université de Liège - ULg > Chimie et bio-industries > Chimie biologique industrielle >]
Blecker, Christophe mailto [Université de Liège - ULg > Chimie et bio-industries > Technologie des industries agro-alimentaires >]
Paquot, Michel mailto [Université de Liège - ULg > Chimie et bio-industries > Chimie biologique industrielle >]
2012
Polymer Degradation & Stability
Elsevier Science
96
10
1761-1770
Yes (verified by ORBi)
0141-3910
Oxford
United Kingdom
[en] Miscanthus x giganteus ; Ammonia pretreatment ; Formic/acetic acid pretreatment ; Lignin chemical structure ; Lignin characterisation ; Repolymerisation
[en] Miscanthus x giganteus was treated with formic acid/acetic acid/water (30/50/20 v/v) for 3 h at 107 C and 80° C, and soaking in aqueous ammonia (25% w/w) for 6 h at 60 C. The effects of these fractionation processes on chemical structure, physico-chemical properties and antioxidant activity of extracted lignins were investigated. Lignins were characterized by their purity, carbohydrate composition, thermal stability, molecular weight and by Fourier transform infrared (FTIR), 1H and quantitative 13C nuclear magnetic resonance (NMR), adiabatic broadband {13C-1H} 2D heteronuclear (multiplicity edited) single quantum coherence (g-HSQCAD). The radical scavenging activity towards 2,2-diphenyl-1-picrylhydrazyl (DPPH) was also investigated. Formic/acetic acid pretreatment performed in milder conditions (80° C for
3 h) gave a delignification percentage of 44.7% and soaking in aqueous ammonia 36.3%.
Formic/acetic acid pretreatment performed in harsh conditions (107°C for 3 h) was more effective for extensive delignification (86.5%) and delivered the most pure lignin (80%). The three lignin fractions contained carbohydrate in different extent: 3% for the lignin obtained after the formic/acetic acid pretreatment performed at 107 C (FAL-107), 5.8% for the formic/acetic acid performed at 80°C (FAL-80) and 13.7% for the ammonia lignin (AL). The acid pretreatment in harsh conditions (FAL-107) resulted in cleavage of b-O-4' bonds and aromatic C-C. Repolymerisation was thought to originate from formation of new aromatic C-O linkages. Under milder conditions (FAL-80) less b-O-4' linkages were broken and repolymerisation took place to a lesser extent. Ammonia lignin was not degraded to a significant extent and resulted in the highest weight average 3140 g mol -1. Despite the fact of FAL-107 repolymerisation,
significant phenolic hydroxyls remained free, explaining the greater antioxidant activity.
Région wallonne : Direction générale des Technologies, de la Recherche et de l'Energie - DGTRE
TECHNOSE project number 716757
http://hdl.handle.net/2268/97740

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