Alkali pulping of sugarcane bagasse for cellulose-enriched pulp with potential for textile applications: Chemical, structural, and thermal characterization

Sugarcane bagasse, a major by-product of the sugar industry, is an abundant and renewable lignocellulosic biomass with considerable potential as a source of cellulose for value-added fibrous materials. In the present study, the effects of alkali pulping conditions on the recovery, chemical composition, degree of polymerization (DP), water absorbency, and physicochemical characteristics of cellulose-enriched pulp obtained from sugarcane bagasse were systematically investigated, with particular consideration of its suitability for subsequent textile-oriented processing. Bagasse was subjected to sodium hydroxide treatment at concentrations ranging from 2 to 8 wt% at 95 °C for 1.5–3.0 h, followed by EDTA chelation and hydrogen peroxide bleaching. The structural and thermal characteristics of the extracted cellulose-rich pulp were evaluated using UV–Visible spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Increasing alkali concentration promoted the removal of lignin and hemicellulosic components, as evidenced by changes in chemical composition and reduced UV absorbance in the lignin-associated region. However, excessive alkali treatment resulted in a decrease in DP, indicating partial degradation of cellulose chains under severe processing conditions. Among the investigated conditions, treatment with 6 wt% NaOH for 2.5 h provided a favourable balance between cellulose enrichment and preservation of polymer chain length, yielding a cellulose-rich pulp with a DP of 820 ± 11 and improved water absorbency. XRD analysis showed an increase in the apparent crystallinity index from 54% to 72.4% following alkali treatment, indicating modification of the structural organization of the cellulose-rich material. TGA and DSC analyses further revealed changes in the thermal behaviour of the extracted pulp. Overall, the findings demonstrate that controlled alkali pulping can produce cellulose-enriched pulp from sugarcane bagasse with modified chemical, structural, and thermal characteristics. The resulting pulp may serve as a potential precursor for further development of regenerated cellulose fibres. However, its suitability for textile applications remains to be established through subsequent fibre formation, spinnability assessment, and mechanical testing.