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Solid acid catalysts are widely used in the field of biomass catalytic conversion owing to their advantages of low environmental pollution, easy separation and reusability. Nevertheless, there are relatively few studies on the mechanism of solid acid liquefaction for biomass. In this study, the effect of acid strength and acid amount of various solid acids on the liquefaction efficiency has been investigated using waste bamboo sawdust generated from the pulp and paper industry as the raw material. In addition, the physicochemical changes of cellulose, hemicellulose and lignin during the reaction process of bamboo sawdust have been studied, and the liquefaction mechanism of bamboo sawdust under the action of various solid acids has been concluded. As a result, the liquefaction efficiency of bamboo sawdust under the polyol system of PEG400/propanetriol is mainly related to the acid strength of the solid acid, and the greater the acid strength of the solid acid, the better the catalytic effect on the bamboo sawdust, in which the residual amount of bamboo sawdust liquefaction catalyzed by the SPA catalyst is only 17.72%. Noteworthy, the most difficult component to liquefy is the crystallization of natural cellulose I into cellulose II during the reaction process, which is the primary obstacle to the complete liquefaction of bamboo sawdust by solid acid. Overall, these findings are valuable for the high value utilization of waste bamboo sawdust in the pulp and paper industry, as well as the application of solid acid catalytic technology for biomass., Competing Interests: Author ZX was employed by Yibin Paper Industry Co., Ltd. Author LW was employed by China Pulp and Paper Research Institute Co., Ltd. Author GF was employed by Shandong Huatai Paper Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Wu, Tang, Huang, Zhao, Liang, Xie, Wei, Fang and Wu.)

This study introduces environmentally-friendly nanocellulose-based membranes for AZO dye (methylene blue, MB) removal from wastewater. These membranes, made of cellulose nanocrystals (CNCs), carboxymethyl cellulose (CMC), zeolite, and citric acid, aim to offer eco-friendly water treatment solutions. CNCs, obtained from sugarcane bagasse, act as the foundational material for the membranes. The study aims to investigate both the composition of the membranes (CMC/CNC/zeolite/citric acid) and the critical adsorption factors (initial MB concentration, contact time, temperature, and pH) that impact the removal of the dye. After systematic experimentation, the optimal membrane composition is identified as 60% CNC, 15% CMC, 20% zeolites, and 5% citric acid. This composition achieved a 79.9% dye removal efficiency and a 38.3 mg/g adsorption capacity at pH 7. The optimized membrane exhibited enhanced MB dye removal under specific conditions, including a 50 mg adsorbent mass, 50 ppm dye concentration, 50 mL solution volume, 120-min contact time, and a temperature of 25°C. Increasing pH from neutral to alkaline enhances MB dye removal efficiency from 79.9% to 94.5%, with the adsorption capacity rising from 38.3 mg/g to 76.5 mg/g. The study extended to study the MB adsorption mechanisms, revealing the chemisorption of MB dye with pseudo-second-order kinetics. Chemical thermodynamic experiments determine the Freundlich isotherm as the apt model for MB dye adsorption on the membrane surface. In conclusion, this study successfully develops nanocellulose-based membranes for efficient AZO dye removal, contributing to sustainable water treatment technologies and environmental preservation efforts., Competing Interests: Author MI was employed by NanoFab Technology Company. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The authors declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (Copyright © 2024 Ibrahim, Salama, Zahran, Abdelfattah, Alsalme, Bechelany and Barhoum.)