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Dissolved pulp refers to pulp of high cellulose content which is used to manufacture various cellulose-derived products such as regenerated fibers or films (e.g., Viscose, Lyocell), cellulose esters (acetates, propionates, butyrates, nitrates) and cellulose ethers (carboxymethyl-, ethyl-, methyl-celluloses). With the rapid development of the global economy and a constant increase in population, the overall demand for dissolved pulp is rising. Dissolved pulp is generally made by the prehydrolysis kraft and acid sulfite processes comprising additional purification stages such as hot and cold caustic extraction. Dilute sulfuric acid is the most commonly used solvent for prehydrolysis of biomass to produce the dissolved pulp. However, cellulose is seriously degraded and the equipment is corroded while the prehydrolysis with sulfuric acid is performed. Oxalic acid, as an organic acid, has a better prehydrolysis selectivity than some mineral acids such as sulfuric acid or hydrochloric acid. The purpose of this paper is to clarify bamboo lignin removal during the bamboo prehydrolysis with oxalic acid to improve the prehydrolysis process for dissolved pulp. The acid-insoluble lignin contents were determined with 72% H2SO4 according to the TAPPI standard test method (T 222 om-06) at different prehydrolysis periods. The distribution of pseudo-lignin on the surface of bamboo fibers was observed by FE-SEM. The chemical structural changes of bamboo lignin were studied by means of CP/MAS 13C-NMR. The results show that the yield decreased with the extension of prehydrolysis time as most of the hemicellulose and a little of the lignin and cellulose were degraded under the acid prehydrolysis conditions. As an increased amount of oxalic acid was applied for prehydrolysis, an increased drop of the yield was obtained. The lignin content based on the prehydrolysed bamboo chips increased with the extension of prehydrolysis time due to a predominant degradation of hemicellulose, the increased amount of oxalic acid and the higher lignin content. However, the lignin content based on the bamboo chips increased dramatically after an initial decline with the extension of prehydrolysis time due to the condensation between the lignin degradation products and carbohydrates, and the formation of pseudo-lignin. As an increased amount of oxalic acid was used for prehydrolysis of bamboo, a greater increase in the rate of lignin content was obtained. The bamboo lignin has more phenolic hydroxyls due to the breakdown of aryl-ether bonds (β -O-4) during the oxalic acid prehydrolysis of bamboo. The pseudo-lignin originating from carbohydrates including cellulose and hemicellulose could attach to the surface of bamboo fibers in the form of microspheres. [ABSTRACT FROM AUTHOR]

[Display omitted] Developing highly efficient, sustainable carbon cathodes is essential for emerging Zn-ion hybrid supercapacitors (ZICs). Herein, lignin's novel chemical modification (amination) has been developed to produce high quantity pyrrolic-N moieties as active sites. Furthermore, chemically modified amine moieties in lignin are vital as a natural self-activating template to generate hierarchical porosity in the 2D (graphene-like) architecture with exceedingly high surface area (2926.4 m2g−1). The rationally introduced dominated pyrrolic-N moieties boost the Zn-ion storage capacity and reaction kinetics due to the dual energy storage mechanism and efficient charge transfer between pyrrolic-N and Zn+2 ions. Furthermore, the pyrrolic-N species are energetically favorable for the adsorption of Zn+2 ions by the formation of N -Zn+2 chemical bonds. Besides, the nitrogen oxides reduce the intrinsic resistance and induce a more polarized surface, resulting in high wettability and efficient transfer of electrolytes into the pores of hydrophobic carbon materials. Subsequently, the chemically modified lignin-derived activated carbon material (Chem-ACM) as a cathode in ZICs delivers a high capacity of 161.2 mA h g−1 at 1 A g−1 with the admirable energy density of 106.7 W h kg−1 at 897 W kg−1 and excellent retention capacity (94%) after 10,000 cycles. Mainly, the assembled quasi solid-state ZICs using Chem-ACM retains the remarkable storage capacity (202 mA h g−1 at 0.2 Ag−1) even at a high bending angle. Notably, the Chem-ACM has been further employed in symmetric supercapacitors as an electrode, and it displays exceptional specific capacitance of 354 Fg−1 at 0.5 Ag−1 with tremendous energy (43.5 W h kg−1) and the power density (0.53 kW kg−1). Additionally, the charge storage capability of Chem-ACM is positively dependent on high nitrogen contents, and it is extrapolated that pyrrolic-N moieties are dominant active sites. Hence, the designed amination-assisted biocarbon synthesis provides a new way to prepare high nitrogen-containing biocarbon for ZICs and further understand pyrrolic-N species' impact on Zn-ion storage. [ABSTRACT FROM AUTHOR]

In recent years, various biomacromolecule-based hydrogels have been extensively and deeply studied in the field of wearable electronics. However, the application of lignin-based hydrogels in flexible devices is still in its infancy. This is mainly due to the significant differences in physical and chemical properties of industrially extracted lignin. In order to seek the universal applicability of diversified lignin in the preparation of hydrogel electronics, we mainly paid attention to the natural physical and chemical properties of lignin to discuss feasible solutions for functional gel design. These properties include chemical reactivity, UV shielding, antibacterial, bio-degradability, anti-oxidation, etc. Finally, in view of lignin's unique properties and the demand for high-quality flexible electronics, some insights are proposed regarding the future research and development directions of lignin-based hydrogel electronics. [ABSTRACT FROM AUTHOR]

To further explore the factors that resist hemicelluloses degradation and release, the chemical composition and molecular weight (MW) in both the interior and exterior portions of the hydrothermally pretreated bamboo substrates were characterized. The chemical composition analysis showed that pretreatment made the lignin tend to accumulate on the exterior surface of the bamboo chips; and therefore gave rise to a large difference of lignin content between exterior and interior. Along with the degradation of hemicelluloses, the difference of hemicelluloses content in both the exterior and interior part became small. On the contrary, the hemicelluloses from the both exterior and interior portions had an invariable MW in the early stage of pretreatment; whereas, the difference of hemicelluloses MW between the exterior and interior part increased with the pretreatment continue, indicating low MW of hemicelluloses in the interior portion. Long time pretreatment promoted increasingly lignin covering on the surface of the chips; the lignin coatings might act as a hydrophobic layer blocking the access of the degraded hemicelluloses. [ABSTRACT FROM AUTHOR]

• The asymmetric hydrogel is adjusted and assembled by lignin and cellulose derivatives. • The hydrogel exhibits completely asymmetric adhesion, strength, and electriferous. • The hydrogel-based sensor has excellent skin adaptability and application stability. • The hydrogel can be applied to self-adhesive bioelectrodes and self-powered sensors. Mechanical adaptability, great wearability, application stability, and self-powered sensing characteristics are important requirements for hydrogel-based strain sensors. In this study, a novel double-layer hydrogel was fabricated with asymmetrical adhesion, strength, and electriferous properties. Wherein, the lignosulfonate sodium (LS)-borax mediated bottom hydrogel layer exhibits excellent softness (Young's modulus: ~14.2 kPa) and skin-adhesion (Adhesive strength: ~18.7 kPa) while the quaternary hydroxyethyl cellulose (QHEC) mediated top hydrogel layer demonstrates great mechanical strength (Young's modulus: ~101.3 kPa) and non-adhesive (Adhesive strength: ~2.2 kPa) properties. These complementary asymmetrical adhesion and strength properties endow the hydrogel-based sensor with exceptionally stable sensing performance and adaptive wearability; moreover, the lignocellulosic materials utilization plays a significant role in the designability, antibacterial and biodegradable properties. In addition, the synergy of negative LS (-) and positive QHEC (+) particles enables the double-layer hydrogel great self-powered sensing because of the directional movement of free ions initiated by the external mechanical stimulus. This study presents a hierarchical design idea of wearable electronics, which will have potential applications in many fields from wearable bioelectrodes to self-powered sensors. [ABSTRACT FROM AUTHOR]