Fig. 1 Description of the present wood fractionation experimental study and lignin solubilization mechanism. (A) Schematic flow diagram shows wood fractionation using p-TsOH for the production of fibers, lignocellulosic nanomaterials, sugars, and LNPs. Processes with dashed lines were not carried out in this study. (B) Schematics of carbohydrate and lignin solubilization by p-TsOH (Cp-TsOH > MHC) and precipitation (Cp-TsOH ≤ MHC).
Fig. 2 Effects of reaction conditions on dissolution (1 − R) of lignin (●) and carbohydrates (glucan, ⬢; xylan, ⬟; mannan, ◆). R is based on the component in untreated poplar wood. (A) p-TsOH concentration effects for 20 min at 80°C. (B) Temperature effects at p-TsOH concentration P = 75 wt % for 20 min. (C and D) Time effects at P = 75 wt % and 80°C (C) and at P = 80 wt % and 80°C (D).
Fig. 3 Determining the p-TsOH MHC by (A) measuring the conductivities of aqueous p-TsOH solutions of different concentrations, showing discontinuity at the p-TsOH MHC of 11.5 wt % and by (B) measuring the effective size of lignin particles in diluted spent p-TsOH liquors using DLS [inset shows images of the diluted spent p-TsOH liquor with (bottom) and without (top) centrifugation].
Fig. 4 Demonstration of centrifugation for fractionating solubilized LNPs. (A) AFM images of LNPs in a diluted spent p-TsOH liquor of 10 wt % that is produced using Wiley-milled NE222 at P75T80t20. (B) AFM-measured topographical height profiles corresponding to lines 1 and 2 in (A). (C to E) AFM images of LNPs in the supernatant from the centrifuged sample in (A) at different speeds for 10 min, at 3000g (C), at 10,000g (D), and at 15,000g (E). (F) AFM-measured topographical height distributions of samples shown in (C) to (E).
- Table 1 Chemical compositions of p-TsOH fractionated poplar NE222 samples under different treatment conditions.
The numbers in the parentheses are component yields based on components in the untreated NE222. Numbers indicate what percent of the sum of the integrals for structures Aa and Ca is accounted for by the integral for each individual structure.
Sample label WISs Spent liquor Solids yield (%) Glucan (%) Xylan (%) Mannan (%) Lignin (%) Glucose
(g/liter)Xylose
(g/liter)Mannose
(g/liter)Acetic acid
(g/liter)Furfural
(g/liter)*Untreated NE222 100 45.7 14.9 4.6 23.4 P70T50t20 78.9 56.8 (97.9) 8.8 (46.7) 3.3 (56.4) 20.6 (69.4) P70T65t20 68.4 61.6 (92.2) 6.5 (29.8) 4.3 (63.9) 11.8 (34.4) P70T50t35 74.4 62.2 (101.1) 7.4 (37.0) 4.3 (68.9) 19.2 (61.0) 1.1 (2.2) 8.9 (52.4) 1.0 (20.3) 1.1 0.05 (0.5) P70T65t35 64.1 68.0 (95.3) 6.6 (28.4) 4.6 (64.0) 13.0 (35.7) 1.3 (2.5) 10.1 (59.5) 1.5 (29.9) 1.5 0.08 (0.7) P70T80t35 55.5 67.3 (81.7) 4.9 (18.3) 4.2 (50.5) 6.7 (15.8) 1.8 (3.6) 11.6 (68.3) 2.0 (38.7) 1.5 0.19 (1.7) P70T80t20 58.9 63.0 (81.1) 6.5 (24.5) 4.3 (53.8) 8.8 (22.1) 1.5 (3.0) 11.0 (65.0) 1.8 (35.2) 1.6 0.13 (1.2) P75T65t05 67.1 56.2 (82.4) 6.5 (29.3) 4.1 (60.0) 15.0 (42.9) 1.2 (2.4) 10.1 (59.7) 1.5 (29.3) 1.5 0.07 (0.6) P75T65t20 60.7 71.8 (95.4) 5.8 (23.8) 4.9 (63.7) 10.8 (28.0) 1.4 (2.7) 10.8 (64.0) 1.7 (32.4) 1.5 0.10 (0.9) P75T65t35 59.0 71.7 (94.5) 6.0 (23.9) 4.0 (51.3) 8.9 (22.3) 1.3 (2.6) 10.3 (60.8) 1.7 (32.4) 1.4 0.10 (0.9) P75T65t60 57.0 74.7 (93.1) 5.0 (19.2) 4.3 (52.8) 7.4 (17.9) 1.7 (3.2) 10.7 (63.4) 1.8 (34.6) 1.5 0.14 (1.2) P75T80t20 55.0 72.4 (87.1) 5.2 (19.1) 4.4 (52.7) 6.1 (14.4) 1.8 (3.6) 10.9 (64.2) 2.0 (39.7) 1.5 0.19 (1.7) P80T80t20 51.9 72.3 (81.9) 3.7 (13.0) 3.7 (41.8) 4.2 (9.2) 2.3 (4.6) 9.9 (58.4) 2.2 (43.9) 1.4 0.33 (3.1) P80T80t35 50.8 75.0 (83.4) 3.6 (12.3) 2.9 (31.7) 4.8 (10.4) P80T80t60 57.6 68.2 (85.9) 3.2 (12.4) 2.4 (30.0) 8.3 (20.3) *Expressed as a percentage of total lignin content (G + S + S′ ) in each sample spectrum.
- Table 2 Physical and chemical properties of the LNPs from dissolved lignin under three p-TsOH fractionation conditions.
Sample
AbbreviationDLS diameter
(nm)Zeta potential
(mV)Molecular weight Mw Mn Mw/Mn LNP-P70T50t20 349.7 ± 1.5 −40.0 ± 0.2 6900 2000 3.45 LNP-P70T65t20 371.7 ± 8.4 −36.5 ± 0.2 5800 2100 2.76 LNP-P75T80t20 467.1 ± 2.5 −37.9 ± 3.6 5400 2000 2.70 - Table 3 Structural characteristics (lignin interunit linkages, PB, aromatic units, and S/G ratio) from integration of 1H–13C correlation peaks in the HSQC spectra of the WCW and three dissolved lignins from poplar wood.
Numbers for Lignin Interunit linkages are percent of the sum of the integrals for structures Aa and Ca is accounted for by the integral for each individual structure. Numbers for PB2/6 are percentage of total lignin content (G + S + S′ ) in each sample spectrum.
WCW P75T80t20 P70T65t20 P70T50t20 Lignin interunit linkages β-O-4 aryl ethers (A) 93 — 87 87 Resinols (C) 7 — 13 13 p-Hydroxybenzoates (PB2/6) 14 — 22 20 Lignin aromatic units G (%) 36 — 30 34 S (%) 64 — 70 66 S/G ratio 1.8 — 2.3 1.9
Supplementary Materials
Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/9/e1701735/DC1
fig. S1. Optical microscopy images of wood fibers produced using p-TsOH fractionation under low-severity conditions (fiber lignin content, 16%), followed by mechanical refining to 550-ml Canadian Standard Freeness.
fig. S2. GPC-measured molecular weight distribution of LNPs from fractionation of Wiley-milled poplar NE222 using p-TsOH under three different conditions.
fig. S3. Catalysis of carbohydrate hydrolysis and lignin degradation by p-TsOH.
table S1. Duplicate fractionation runs under six sets of conditions to demonstrate the repeatability of p-TsOH fractionation experiments.
table S2. Comparisons of chemical compositions of fractionated poplar NE222 WISs between the first cycle using fresh p-TsOH solution and the recycle run using spent p-TsOH acid liquor.
Additional Files
Supplementary Materials
This PDF file includes:
- fig. S1. Optical microscopy images of wood fibers produced using p-TsOH fractionation under low-severity conditions (fiber lignin content, 16%), followed
by mechanical refining to 550-ml Canadian Standard Freeness.
- fig. S2. GPC-measured molecular weight distribution of LNPs from fractionation of
Wiley-milled poplar NE222 using p-TsOH under three different conditions.
- fig. S3. Catalysis of carbohydrate hydrolysis and lignin degradation by p-TsOH.
- table S1. Duplicate fractionation runs under six sets of conditions to demonstrate
the repeatability of p-TsOH fractionation experiments.
- table S2. Comparisons of chemical compositions of fractionated poplar NE222 WISs between the first cycle using fresh p-TsOH solution and the recycle run using spent p-TsOH acid liquor.
Files in this Data Supplement:
- fig. S1. Optical microscopy images of wood fibers produced using p-TsOH fractionation under low-severity conditions (fiber lignin content, 16%), followed
by mechanical refining to 550-ml Canadian Standard Freeness.
