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Lignin depolymerization to aromatic monomers with high yields and selectivity is essential for the economic feasibility of many lignin-valorization strategies within integrated biorefining processes. Importantly, the quality and properties of the lignin source play an essential role in impacting the conversion chemistry, yet this relationship between lignin properties and lignin susceptibility to depolymerization is not well established. In this study, we quantitatively demonstrate how the detrimental effect of a pretreatment process on the properties of lignins, particularly β-O-4 content, limit high yields of aromatic monomers using three lignin depolymerization approaches: thioacidolysis, hydrogenolysis, and oxidation. Through pH-based fractionation of alkali-solubilized lignin from hybrid poplar, this study demonstrates that the properties of lignin, namely β-O-4 linkages, phenolic hydroxyl groups, molecular weight, and S/G ratios exhibit strong correlations with each other even after pretreatment. Furthermore, the differences in these properties lead to discernible trends in aromatic monomer yields using the three depolymerization techniques. Based on the interdependency of alkali lignin properties and its susceptibility to depolymerization, a model for the prediction of monomer yields was developed and validated for depolymerization by quantitative thioacidolysis. These results highlight the importance of the lignin properties for their suitability for an ether-cleaving depolymerization process, since the theoretical monomer yields grows as a second order function of the β-O-4 content. Therefore, this research encourages and provides a reference tool for future studies to identify new methods for lignin-first biomass pretreatment and lignin valorization that emphasize preservation of lignin qualities, apart from focusing on optimization of reaction conditions and catalyst selection.
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This content will become publicly available on November 15, 2026
Nitro-oxidation process for sustainable production of carboxylated lignin-containing cellulose nanofibers from sugarcane bagasse
This study demonstrated a sustainable, zero-waste approach to produce carboxylated lignin-containing cellulose nanofibers (LCNFs) directly from untreated sugarcane bagasse (SCB) using nitro-oxidation process (NOP) fol lowed by high-pressure homogenization. Systematic optimization of reaction parameters was conducted, including reaction time, HNO3-to-SCB ratio, HNO3 concentration, temperature, and co-oxidant addition (KNO₂). The results revealed that HNO3 concentration played the most dominant role in tailoring LCNF properties. Notably, the resulting LCNFs exhibited high dispersibility, with zeta potential values ranging from 38 to 65 mV due to the increasing surface carboxyl content (0.43 to 1.21 mmol/g) even under relatively mild conditions (e.g., 50 ◦C, 5 h). Lowering the acid concentration significantly increased the lignin content, enhancing the thermal stability. All LCNFs exhibited nanoscale diameters (7–13 nm), high crystallinity (54 to 70 %), and shear- thinning behavior. Elemental analysis of NOP effluents confirmed their enrichment with macro- and micro- nutrients, enabling their reuse as biofertilizers. This dual valorization of solid and liquid products positions NOP as a viable nanocellulose production and nutrient recovery pathway from lignocellulosic biomass. Resulting LCNFs, with their amphiphilic, biodegradable, and tunable surface properties, represent a compelling platform to make new materials to replace some synthetic polymers and reduce microplastic and chemical pollution.
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- Award ID(s):
- 2216585
- PAR ID:
- 10639348
- Publisher / Repository:
- Elsevier Ltd
- Date Published:
- Journal Name:
- Carbohydrate polymers
- Volume:
- 368
- Issue:
- 2
- ISSN:
- 0144-8617
- Page Range / eLocation ID:
- 124109
- Subject(s) / Keyword(s):
- Sugarcane bagasse Nitro-oxidation Lignin-containing Nanocellulose Carboxylated cellulose nanofibers Zero-waste processing
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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