The structure and chemical composition of cell walls play a vital role in the bioconversion and utilization of plants. In the present study, the cell wall structure and chemical composition of pith and rind from sunflower stalks were compared and correlated to their nanofibrillation efficiency with ultrasonic treatment. Mild chemical pretreatment using 1% or 4% NaOH without any bleaching process were applied prior to ultrasonication nanofibrillation. Significant structural and chemical differences were demonstrated between the pith and rind, with the former exhibiting a much lower lignin and hemicellulose contents, higher pectin, much looser cell structure and higher cell wall porosity than the latter. Alkaline treatment alone was sufficient to eliminate most of the hemicellulose and pectin from stalk pith, whereas only partial removal of hemicellulose and lignin was achieved for the woody rind part. After 30 min of ultrasonic treatment, the stalk pith exhibited fully defibrillated fibrils with a continuous and entangled micro/nanofibrillated network, whereas numerous micron-sized fiber and fragments remained for the rind. The results indicated that stalk pith is less recalcitrant and easier to be fibrillated with ultrasonication than rind, which must be correlated to their distinct differences in both structure and chemical composition.

Steam explosion processing of bamboo generates substantial quantities of granular residues that are often discarded, leading to resource waste and potential secondary pollution. In this study, a sustainable upcycling strategy was developed to convert these residues into mechanically reinforced cellulose-based composite films. Cellulose isolated from steam-exploded bamboo residues was separately converted into negatively charged TEMPO-oxidized cellulose nanofibrils (TOCNFs) and positively charged quaternized cellulose (QCell), with the latter prepared through modification using 2,3-epoxypropyltrimethylammonium chloride. The oppositely charged cellulose components were subsequently assembled into TOCNF/QCell composite films through electrostatic interactions. At an optimal TOCNF-to-QCell mass ratio of 3:1, the resulting composite film exhibited a tensile strength of 134 MPa, representing an improvement of 23.09% compared with that of the corresponding unmodified TOCNF₁/Cell₁ film. SEM observations revealed that the enhanced interfacial interactions facilitated the formation of a dense and compact network structure, thereby contributing to the improved mechanical performance. Although quaternization exerted little influence on the equilibrium moisture uptake of the films, it markedly reduced moisture sorption–desorption hysteresis, indicating enhanced structural reversibility during humidity cycling without substantially altering their overall hydrophilicity. FTIR and XPS analyses confirmed the successful chemical modification of cellulose, while thermogravimetric analysis demonstrated that the thermal stability of the cellulose-based films was largely preserved. Overall, these findings provide a sustainable and effective route for valorizing steam-exploded bamboo residues into high-performance cellulose-based materials.

Raw lignocellulosic biomass offers a low-input route for nutrient capture, yet its internal tissue heterogeneity is rarely considered when adsorption behavior is interpreted. Here, Giant Juncao (Pennisetum giganteum; also reported as Cenchrus fungigraminus) straw was separated into rind and pith to determine how native tissue architecture and cell-wall chemistry relate to ammonium (NH₄⁺) and phosphate adsorption. The pith occupied 72.33% of stem volume but only 26.85% of dry mass and had a much lower basic density than the rind (0.072 vs. 0.570 g·cm⁻³). It also showed a larger N₂-accessible specific surface area (2.67 vs. 1.13 m²·g⁻¹), greater pore volume (0.006 vs. 0.001 cm³·g⁻¹), higher pectin content (20.58 vs. 14.81 mg·g⁻¹), and lower cellulose crystallinity (48.28% vs. 57.30%). These contrasts were accompanied by tissue-dependent NH₄⁺ uptake: the rind and pith adsorbed 4.19 ± 1.02 and 10.36 ± 1.54 mg·g⁻¹, respectively, whereas whole straw reached 13.80 ± 0.23 mg·g⁻¹ under the same comparison conditions. Phosphate uptake was less tissue-sensitive (19.57–22.40 mg·g⁻¹). More than 90% of the 24 h uptake was reached within 60 min. Nonlinear least-squares fitting, evaluated by multiple criteria (R², SSE, RMSE, χ², or AIC), identified the pseudo-second-order kinetic model and the Langmuir–Freundlich isotherm as the best empirical descriptions of the measured data. Spectroscopic changes were consistent with participation of oxygen-containing cell-wall groups in nutrient retention, but did not uniquely resolve molecular binding pathways. The results show that tissue-scale architecture and heterogeneous lignocellulosic chemistry jointly shape nutrient uptake in minimally processed Giant Juncao and support further evaluation of the unseparated feedstock in real wastewater and nutrient-reuse scenarios.

Petroleum-based plastics are non-renewable and degrade poorly, persisting in the environment and causing serious ecological pollution, so urgent development of alternatives is needed. In this study, all-bamboo fiber thermosetting plastics (BTPs) were successfully prepared through selective sodium periodate oxidation of bamboo fibers followed by hot-pressing. The results demonstrate that the oxidation treatment effectively enhanced fiber reactivity and facilitated the formation of dense composite materials during hot-pressing. Compared with petroleum-based plastics (e.g., PVC), BTPs exhibit outstanding mechanical properties: flexural strength reaches 100.73 MPa, tensile strength reaches 83.31 MPa, while the 72 h water absorption and thickness swelling rates are as low as 5.36% and 4.59%, respectively. This study also reveals the mechanism by which residual lignin affects material microstructure formation through competitive oxidation reactions. Although it imparts initial hydrophobicity, it hinders complete fiber activation, leading to the formation of micro-defects. Furthermore, BTPs can completely degrade in 1% NaOH solution within 24 h, demonstrating excellent degradability. This research provides a new strategy for developing high-performance, degradable all-bamboo-based materials and promotes the value-added utilization of bamboo resources.