Alkalization of Kraft Pulps from Pine and Eucalyptus and Its Effect on Enzymatic Saccharification and Viscosity Control of Cellulose
Abstract
:1. Introduction
2. Materials and Methods
2.1. Materials
2.2. Bleached Kraft Pulps
2.3. Cold Caustic Extraction (CCE)
2.4. Chemical Characterization
2.5. Fiber Biometry
2.6. Intrinsic Viscosity
2.7. Carboxyl Content
2.8. Specific Surface Area (SSA) from Methylene Blue (MB) Adsorption (SSAMB)
MB Adsorption and Langmuir Isotherm
2.9. X Ray Diffraction of Pulp Samples
2.10. Enzymatic Multicomponent Saccharification of Pulps
2.11. Endoglucanase Treatment of Pulps for Viscosity Reduction
2.12. Data Analysis
3. Results and Discussion
3.1. Chemical Composition and Fiber Biometry
3.2. Specific Surface Area by Methylene Blue (MB) Adsorption (SSAMB)
3.3. Cellulose Crystallinity
3.4. Intrinsic Viscosity
3.5. Carboxyl Content
3.6. Influence of CCE Treatment on Pulp Features
3.7. Enzymatic Multicomponent Saccharification of Pulps
3.8. Endoglucanase (EG) Treatment of Pulps for Viscosity Control
4. Conclusions
- (1)
- CCE treatment was able to generate modifications in chemical composition and crystallinity of eucalyptus and pine bleached kraft pulps. NaOH concentrations above 17.5% cause a depolymerization of the cellulose chains, a decrease in fiber length and in CrI. Furthermore, eucalyptus started the conversion of cellulose I to cellulose II at NaOH 10%, while in pine it occurs at 17.5% NaOH.
- (2)
- Enzymatic saccharification yields higher than 90% where obtained with CCE-treated eucalyptus pulps while in bleached pulp it was 80%. In pine, only CCE-treated pulps with higher proportion of cellulose II showed saccharification yields higher than 90%.
- (3)
- CCE combined with EG treatment is an efficient method to control the intrinsic viscosity of pulps. The eucalyptus samples showed higher susceptibility to the EG treatment than the pine samples, which was mainly related to the low crystallinity of the pulps.
- (4)
- Overall, eucalyptus pulps are more accessible and reactive than pine pulps. The objective of increasing the reactivity, converting cellulose I to cellulose II hydrate, proved to be relevant only for the saccharification of pine pulps.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
References
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Sample | Treatment | Glucans (%) | Xylans 1 or Mannans 2 (%) | Fiber Length (mm) | Fiber Width (um) | Fines Content (%) | Mean Kink Index |
---|---|---|---|---|---|---|---|
Eucalyptus 1 | Bleached | 90.2 ± 1 | 9.8 ± 0.2 | 0.69 ± 0.01 | 18.1 ± 0.1 | 4.4 ± 0.1 | 3 ± 0 |
CCE5 | 93.6 ± 1 | 6.5 ± 0.1 | 0.647 ± 0.004 | 18.1 ± 0.1 | 4.5 ± 0.2 | 3.8 ± 0.3 | |
CCE10 | >99 | <1 | 0.575 ± 0.001 | 18 ± 0 | 5.8 ± 0.3 | 3.79 ± 0.01 | |
CCE17.5 | >99 | <1 | 0.536 ± 0.004 | 17 ± 0 | 7 ± 1 | 4 ± 0.03 | |
CCE35 | >99 | <1 | 0.59 ± 0.08 | 17.3 ± 0.4 | 5 ± 1 | 3.83 ± 0.03 | |
Pine 2 | Bleached | 92 ± 1 | 7.5 ± 0.4 | 2.224 ± 0.004 | 32.5 ± 0.2 | 3.1 ± 0.1 | 3 ± 0.1 |
CCE5 | 93.2 ± 0.2 | 6.5 ± 0.2 | 2.19 ± 0.02 | 32.5 ± 0.1 | 2.3 ± 0.1 | 3.3 ± 0.1 | |
CCE10 | 94 ± 3 | 5.5 ± 1.1 | 2.031 ± 0.001 | 33.1 ± 0.1 | 2.5 ± 0.1 | 3.99 ± 0.04 | |
CCE17.5 | >99 | <1 | 1.79 ± 0.03 | 31.6 ± 0.4 | 3 ± 1 | 4.1 ± 0.4 | |
CCE35 | >99 | <1 | 1.74 ± 0.02 | 31.5 ± 0.5 | 2.4 ± 0.4 | 4.2 ± 0.1 |
Carboxyl Content | Intrinsic Viscosity | CrI | SSA | FL | FW | Fines | Kink Index | Xylans Content | Glucans Content | |
---|---|---|---|---|---|---|---|---|---|---|
Carboxyl content | 1 | 0.11 | 0.32 | 0.85 * | 0.80 | 0.47 | −0.65 | −0.93 * | 0.83 * | −0.83 * |
Intrinsic viscosity | 1 | 0.91 * | 0.37 | 0.38 | 0.79 | −0.15 | −0.38 | 0.48 | −0.48 | |
CrI | 1 | 0.63 | 0.69 | 0.96 * | −0.52 | −0.55 | 0.74 | −0.74 | ||
SSA | 1 | 0.88 * | 0.70 | −0.72 | −0.81 | 0.97 * | −0.97 * | |||
FL | 1 | 0.84 * | −0.94 * | −0.87 * | 0.95 * | −0.95 * | ||||
FW | 1 | −0.73 | −0.69 | 0.83 * | −0.83 * | |||||
Fines | 1 | 0.69 | −0.81 | 0.80 | ||||||
Kink index | 1 | −0.85 * | 0.86 | |||||||
Xylans content | 1 | 0.99 * | ||||||||
Glucans content | 1 |
Carboxyl Content | Intrinsic Viscosity | CrI | SSA | FL | FW | Fines | Kink Index | Xylans Content | Glucans Content | |
---|---|---|---|---|---|---|---|---|---|---|
Carboxyl content | 1 | 0.45 | 0.56 | 0.52 | 0.75 | 0.13 | 0.37 | −0.93 * | 0.65 | −0.63 |
Intrinsic viscosity | 1 | 0.89 * | 0.78 | 0.80 | 0.77 | −0.25 | −0.59 | 0.77 | −0.76 | |
CrI | 1 | 0.98 * | 0.94 * | 0.85 * | 0.01 | −0.75 | 0.95 * | −0.95 * | ||
SSA | 1 | 0.91 * | 0.84 * | 0.08 | −0.73 | 0.95 * | −0.95 * | |||
FL | 1 | 0.76 | 0.31 | −0.92 * | 0.99 * | −0.98 * | ||||
FW | 1 | 0.07 | −0.45 | 0.83 | −0.84 * | |||||
Fines | 1 | −0.48 | 0.32 | −0.33 | ||||||
Kink index | 1 | −0.86 * | 0.85 * | |||||||
Xylans content | 1 | 0.98 * | ||||||||
Glucans content | 1 |
Specie | Treatment | Lateral Crystallite Size (nm) | D-Spacing (Å) | ||
---|---|---|---|---|---|
CI 1 (200) | CII 2 (110) | CI 1 (200) | CII 2 (110) | ||
Eucalyptus | Bleached | 4.49 | - | 3.95 | - |
CCE5 | 4.51 | - | 3.94 | - | |
CCE10 | 5.01 | 6.79 | 3.94 | 4.40 | |
CCE17.5 | 5.13 | 5.77 | 3.93 | 4.44 | |
CCE35 | - | 6.29 | - | 4.42 | |
Pine | Bleached | 4.97 | - | 3.95 | - |
CCE5 | 5.04 | - | 3.98 | - | |
CCE10 | 5.26 | - | 3.96 | - | |
CCE17.5 | 5.00 | 5.82 | 3.91 | 4.47 | |
CCE35 | - | 5.70 | - | 4.57 |
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Carrillo-Varela, I.; Vidal, C.; Vidaurre, S.; Parra, C.; Machuca, Á.; Briones, R.; Mendonça, R.T. Alkalization of Kraft Pulps from Pine and Eucalyptus and Its Effect on Enzymatic Saccharification and Viscosity Control of Cellulose. Polymers 2022, 14, 3127. https://doi.org/10.3390/polym14153127
Carrillo-Varela I, Vidal C, Vidaurre S, Parra C, Machuca Á, Briones R, Mendonça RT. Alkalization of Kraft Pulps from Pine and Eucalyptus and Its Effect on Enzymatic Saccharification and Viscosity Control of Cellulose. Polymers. 2022; 14(15):3127. https://doi.org/10.3390/polym14153127
Chicago/Turabian StyleCarrillo-Varela, Isabel, Claudia Vidal, Sebastián Vidaurre, Carolina Parra, Ángela Machuca, Rodrigo Briones, and Regis Teixeira Mendonça. 2022. "Alkalization of Kraft Pulps from Pine and Eucalyptus and Its Effect on Enzymatic Saccharification and Viscosity Control of Cellulose" Polymers 14, no. 15: 3127. https://doi.org/10.3390/polym14153127