22 research outputs found
Structural Transformation of Isolated Poplar and Switchgrass Lignins during Dilute Acid Treatment
A key step in conversion of cellulosic
biomass into sustainable
fuels and chemicals is thermochemical pretreatment to reduce plant
cell wall recalcitrance. Obtaining an improved understanding of the
fundamental chemistry of lignin, the most recalcitrant component of
biomass, during pretreatment is critical to the continued development
of renewable biofuel production. To examine the intrinsic chemistry
of lignin during dilute acid pretreatment (DAP), lignin was isolated
from poplar and switchgrass using a cellulolytic enzyme system and
then treated under DAP conditions. Our results highlight that lignin
is subjected to depolymerization reactions within the first 2 min
of dilute acid pretreatment and these changes are accompanied by increased
generation of aliphatic and phenolic hydroxyl groups of lignin. This
is followed by a competing set of depolymerization and repolymerization
reactions that lead to a decrease in the content of guaiacyl lignin
units and an increase in condensed lignin units as the reaction residence
time is extended beyond 5 min. A detailed comparison of changes in
functional groups and molecular weights of cellulolytic enzyme lignins
demonstrated different structural parameters, related to the recalcitrant
properties of lignin, are altered during DAP conditions
Physicochemical Structural Changes of Poplar and Switchgrass during Biomass Pretreatment and Enzymatic Hydrolysis
Converting lignocellulosics to simple
sugars for second generation
bioethanol is complicated due to biomass recalcitrance, and it requires
a pretreatment stage prior to enzymatic hydrolysis. In this study,
native, pretreated (acid and alkaline) and partially hydrolyzed poplar
and switchgrass were characterized by using Simons’ staining
for cellulose accessibility, GPC for degree of polymerization (DP),
and FTIR for chemical structure of plant cell wall. The susceptibility
of the pretreated biomass to enzymatic hydrolysis could not be easily
predicted from differences in cellulose DP and accessibility. During
hydrolysis, the most significant DP reduction occurred at the very
beginning of hydrolysis, and the DP began to decrease at a significantly
slower rate after this initial period, suggesting an existence of
a synergistic action of endo- and exoglucanases that contribute to
the occurrence of a “peeling off” mechanism. Cellulose
accessibility was found to be increased at the beginning of hydrolysis,
after reaching a maximum value then started to decrease. The fresh
enzyme restart hydrolysis experiment along with the accessibility
data indicated that the factors associated with the nature of enzyme
such as irreversible nonspecific binding of cellulases by lignin and
steric hindrance of enzymes should be responsible for the gradual
slowing down of the reaction rate
MOESM1 of A structured understanding of cellobiohydrolase I binding to poplar lignin fractions after dilute acid pretreatment
Additional file 1: Figure S1. 2D-HSQC spectra and the main structures of the isolated lignins: (A) β-aryl-ether units (β-O-4); (B) phenylcoumarane; (C) resinols; (G) guaiacyl units; (S) syringyl units; (S’) oxidized syringyl units bearing a carbonyl at Cα; (PB) p-Hydroxybenzoate units. Condensed lignin was assigned from Sun et al. [8]
Effect of in Vivo Deuteration on Structure of Switchgrass Lignin
Biomass
deuteration is an effective engineering method that can
be used to provide key insights into understanding of biomass recalcitrance
and the complex biomass conversion process. In this study, production
of deuterated switchgrass was accomplished by growing the plants in
50% D<sub>2</sub>O under hydroponic conditions in a perfusion chamber.
Cellulolytic enzyme lignin was isolated from deuterated switchgrass,
characterized by Fourier transform infrared (FTIR), gel permeation
chromatography (GPC), and nuclear magnetic resonance (NMR) and compared
with its protiated control sample to determine the effect of in vivo
deuteration on the chemical structure of lignin. FTIR results showed
that D<sub>2</sub>O can be taken up by the roots and transported to
the leaves, and deuterium was subsequently incorporated into hydroxyl
and alkyl groups in the plant and its lignin through photosynthesis.
According to GPC results, deuterated lignin had slightly higher molecular
weight, presumably due to isotope effects. <sup>31</sup>P and heteronuclear
single quantum coherence (HSQC) NMR results revealed that lignin in
the deuterated biomass preserved its native physicochemical characteristics.
The conserved characteristics of the deuterated lignin show its great
potential applications for structural and dynamic studies of lignocellulose
by techniques such as neutron scattering
Effect of the Lignin Structure on the Physicochemical Properties of Lignin-Grafted-Poly(ε-caprolactone) and Its Application for Water/Oil Separation
Lignin-grafted poly(ε-caprolactone)
copolymers
(lignin-g-PCLs) have shown wide application potentials
in coatings, biocomposites, and biomedical fields. However, the structural
heterogeneity of lignin affecting the structures and properties of
lignin-g-PCL has been scarcely investigated. Herein,
kraft lignin is fractionated into four precursors, namely, Fins, F1, F2, and F3, with declining molecular weights and increased
hydroxyl contents. Lignin-g-PCLs are synthesized via ring-opening polymerization of ε-caprolactone with lignin and characterized by GPC, FTIR, 1H and 31P NMR, DSC, TGA, and iGC. The mechanical properties,
UV barrier, and enzymatic biodegradability of the lignin-g-PCLs are evaluated. Results show that lignin with a higher molecular
weight and aliphatic OH favors the copolymerization, leading to lignin-g-PCLs with longer PCL arms. Moreover, lignin incorporation
improves the thermal stability, hydrophobicity, and UV-blocking ability
but reduces the lipase hydrolyzability of the copolymers. We also
demonstrated that the lignin-g-PCL-coated filter
paper could successfully separate chloroform–, petroleum ether–,
and hexane–water mixtures with an efficiency up to 99.2%. The
separation efficiency remains above 90% even after 15 cycles. The
structural differences of copolymers derived from the fractionation
showed minimal influence on the separation efficiency. This work provides
new insights into lignin-based copolymerization and the versatility
of lignin valorization
Effect of the Lignin Structure on the Physicochemical Properties of Lignin-Grafted-Poly(ε-caprolactone) and Its Application for Water/Oil Separation
Lignin-grafted poly(ε-caprolactone)
copolymers
(lignin-g-PCLs) have shown wide application potentials
in coatings, biocomposites, and biomedical fields. However, the structural
heterogeneity of lignin affecting the structures and properties of
lignin-g-PCL has been scarcely investigated. Herein,
kraft lignin is fractionated into four precursors, namely, Fins, F1, F2, and F3, with declining molecular weights and increased
hydroxyl contents. Lignin-g-PCLs are synthesized via ring-opening polymerization of ε-caprolactone with lignin and characterized by GPC, FTIR, 1H and 31P NMR, DSC, TGA, and iGC. The mechanical properties,
UV barrier, and enzymatic biodegradability of the lignin-g-PCLs are evaluated. Results show that lignin with a higher molecular
weight and aliphatic OH favors the copolymerization, leading to lignin-g-PCLs with longer PCL arms. Moreover, lignin incorporation
improves the thermal stability, hydrophobicity, and UV-blocking ability
but reduces the lipase hydrolyzability of the copolymers. We also
demonstrated that the lignin-g-PCL-coated filter
paper could successfully separate chloroform–, petroleum ether–,
and hexane–water mixtures with an efficiency up to 99.2%. The
separation efficiency remains above 90% even after 15 cycles. The
structural differences of copolymers derived from the fractionation
showed minimal influence on the separation efficiency. This work provides
new insights into lignin-based copolymerization and the versatility
of lignin valorization
Effect of the Lignin Structure on the Physicochemical Properties of Lignin-Grafted-Poly(ε-caprolactone) and Its Application for Water/Oil Separation
Lignin-grafted poly(ε-caprolactone)
copolymers
(lignin-g-PCLs) have shown wide application potentials
in coatings, biocomposites, and biomedical fields. However, the structural
heterogeneity of lignin affecting the structures and properties of
lignin-g-PCL has been scarcely investigated. Herein,
kraft lignin is fractionated into four precursors, namely, Fins, F1, F2, and F3, with declining molecular weights and increased
hydroxyl contents. Lignin-g-PCLs are synthesized via ring-opening polymerization of ε-caprolactone with lignin and characterized by GPC, FTIR, 1H and 31P NMR, DSC, TGA, and iGC. The mechanical properties,
UV barrier, and enzymatic biodegradability of the lignin-g-PCLs are evaluated. Results show that lignin with a higher molecular
weight and aliphatic OH favors the copolymerization, leading to lignin-g-PCLs with longer PCL arms. Moreover, lignin incorporation
improves the thermal stability, hydrophobicity, and UV-blocking ability
but reduces the lipase hydrolyzability of the copolymers. We also
demonstrated that the lignin-g-PCL-coated filter
paper could successfully separate chloroform–, petroleum ether–,
and hexane–water mixtures with an efficiency up to 99.2%. The
separation efficiency remains above 90% even after 15 cycles. The
structural differences of copolymers derived from the fractionation
showed minimal influence on the separation efficiency. This work provides
new insights into lignin-based copolymerization and the versatility
of lignin valorization
Effect of the Lignin Structure on the Physicochemical Properties of Lignin-Grafted-Poly(ε-caprolactone) and Its Application for Water/Oil Separation
Lignin-grafted poly(ε-caprolactone)
copolymers
(lignin-g-PCLs) have shown wide application potentials
in coatings, biocomposites, and biomedical fields. However, the structural
heterogeneity of lignin affecting the structures and properties of
lignin-g-PCL has been scarcely investigated. Herein,
kraft lignin is fractionated into four precursors, namely, Fins, F1, F2, and F3, with declining molecular weights and increased
hydroxyl contents. Lignin-g-PCLs are synthesized via ring-opening polymerization of ε-caprolactone with lignin and characterized by GPC, FTIR, 1H and 31P NMR, DSC, TGA, and iGC. The mechanical properties,
UV barrier, and enzymatic biodegradability of the lignin-g-PCLs are evaluated. Results show that lignin with a higher molecular
weight and aliphatic OH favors the copolymerization, leading to lignin-g-PCLs with longer PCL arms. Moreover, lignin incorporation
improves the thermal stability, hydrophobicity, and UV-blocking ability
but reduces the lipase hydrolyzability of the copolymers. We also
demonstrated that the lignin-g-PCL-coated filter
paper could successfully separate chloroform–, petroleum ether–,
and hexane–water mixtures with an efficiency up to 99.2%. The
separation efficiency remains above 90% even after 15 cycles. The
structural differences of copolymers derived from the fractionation
showed minimal influence on the separation efficiency. This work provides
new insights into lignin-based copolymerization and the versatility
of lignin valorization
Effect of the Lignin Structure on the Physicochemical Properties of Lignin-Grafted-Poly(ε-caprolactone) and Its Application for Water/Oil Separation
Lignin-grafted poly(ε-caprolactone)
copolymers
(lignin-g-PCLs) have shown wide application potentials
in coatings, biocomposites, and biomedical fields. However, the structural
heterogeneity of lignin affecting the structures and properties of
lignin-g-PCL has been scarcely investigated. Herein,
kraft lignin is fractionated into four precursors, namely, Fins, F1, F2, and F3, with declining molecular weights and increased
hydroxyl contents. Lignin-g-PCLs are synthesized via ring-opening polymerization of ε-caprolactone with lignin and characterized by GPC, FTIR, 1H and 31P NMR, DSC, TGA, and iGC. The mechanical properties,
UV barrier, and enzymatic biodegradability of the lignin-g-PCLs are evaluated. Results show that lignin with a higher molecular
weight and aliphatic OH favors the copolymerization, leading to lignin-g-PCLs with longer PCL arms. Moreover, lignin incorporation
improves the thermal stability, hydrophobicity, and UV-blocking ability
but reduces the lipase hydrolyzability of the copolymers. We also
demonstrated that the lignin-g-PCL-coated filter
paper could successfully separate chloroform–, petroleum ether–,
and hexane–water mixtures with an efficiency up to 99.2%. The
separation efficiency remains above 90% even after 15 cycles. The
structural differences of copolymers derived from the fractionation
showed minimal influence on the separation efficiency. This work provides
new insights into lignin-based copolymerization and the versatility
of lignin valorization
Effect of the Lignin Structure on the Physicochemical Properties of Lignin-Grafted-Poly(ε-caprolactone) and Its Application for Water/Oil Separation
Lignin-grafted poly(ε-caprolactone)
copolymers
(lignin-g-PCLs) have shown wide application potentials
in coatings, biocomposites, and biomedical fields. However, the structural
heterogeneity of lignin affecting the structures and properties of
lignin-g-PCL has been scarcely investigated. Herein,
kraft lignin is fractionated into four precursors, namely, Fins, F1, F2, and F3, with declining molecular weights and increased
hydroxyl contents. Lignin-g-PCLs are synthesized via ring-opening polymerization of ε-caprolactone with lignin and characterized by GPC, FTIR, 1H and 31P NMR, DSC, TGA, and iGC. The mechanical properties,
UV barrier, and enzymatic biodegradability of the lignin-g-PCLs are evaluated. Results show that lignin with a higher molecular
weight and aliphatic OH favors the copolymerization, leading to lignin-g-PCLs with longer PCL arms. Moreover, lignin incorporation
improves the thermal stability, hydrophobicity, and UV-blocking ability
but reduces the lipase hydrolyzability of the copolymers. We also
demonstrated that the lignin-g-PCL-coated filter
paper could successfully separate chloroform–, petroleum ether–,
and hexane–water mixtures with an efficiency up to 99.2%. The
separation efficiency remains above 90% even after 15 cycles. The
structural differences of copolymers derived from the fractionation
showed minimal influence on the separation efficiency. This work provides
new insights into lignin-based copolymerization and the versatility
of lignin valorization