Two-Step Cascade Process for Efficient Isolation of Cellulose from Sugarcane Trash

Efficient and sustainable isolation of cellulose from sugarcane tops (ST), a major sub-fraction of sugarcane trash, is of great significance for the high-value valorization of cellulose and its subsequent conversion into substrates for biomaterials. This study introduces a novel two-step cascade process under mild conditions, which integrates two treatments: a green multi-functional depolymerizing agent (MDA) treatment and the alkaline hydrogen peroxide (AHP) treatment. This sequential strategy is designed to selectively solubilize hemicellulose and lignin, respectively, ultimately yielding cellulose from ST. To assess extraction efficacy, four MDA treatment durations (0–3 h) were systematically investigated. The quality of the extracted cellulose was evaluated through lignocellulosic composition analysis, surface morphology, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). Results demonstrate that the MDA treatment effectively disrupted ST’s recalcitrant structure, facilitating selective hemicellulose enrichment in deionized water and lignin dissolution in 1% (w/v) AHP. Notably, cellulose pretreated for 2 h exhibited preferred properties, including high purity (85.82%), a retention rate of 85.33%, preservation of the cellulose I crystalline polymorph (crystallinity index, CrI = 69.11%), and excellent thermal stability (maximum decomposition temperature, Tmax = 344.48 °C). The preserved structural integrity suggests the potential suitability of the extracted cellulose as a promising feedstock for polymer composite applications.