Direct method to isolate cellulose nanofibrils from sugarcane bagasse with pilot plant upscaling

Despite the high performance of TEMPO-oxidized cellulose nanofibrils (TOCNFs) as renewable building blocks, their large-scale production remains limited by multistep chemical pretreatments and high energy consumption. Here, a simplified and scalable route for TOCNF production is presented, in which TEMPO-mediated oxidation is applied directly to milled sugarcane bagasse, followed by low-energy fibrillation. By systematically varying the NaClO dosage (5–25 mmol g −1 ), a progressive increase in carboxylate content (0.54–1.15 mmol g −1 ) and a substantial reduction in lignin content (from 19.0 to 3.3 wt%) were achieved. The resulting nanofibrils exhibited diameters of ~1–2 nm, lengths exceeding 1 μm and a degree of polymerization of 631, forming homogeneous shear-thinning gels (flow index n ≈ 0.2–0.3) with high colloidal stability (ζ-potential down to −56 mV). Atomic force microscopy and AFM-IR analyses revealed the presence of dispersed lignin nanoparticles coexisting with the TOCNF network. Importantly, the process was successfully demonstrated at pilot-scale, achieving an approximately 500-fold increase in production capacity while maintaining a high cellulose yield (91 wt%) and properties comparable to bench-scale materials, including carboxylate content (1.11 vs 1.14 mmol g −1 ), morphology, and colloidal stability. Overall, this work presents an energy-efficient and scalable method for producing TOCNF from waste biomass, simplifying the process and supporting sustainable large-scale nanocellulose manufacturing. • Developed process simplifies operation and adds value to waste biomass. • The direct method simultaneously removes lignin and oxidizes cellulose. • Highly fibrillated, highly charged, and low lignin CNFs are obtained at the best condition. • The process was successfully upscaled to pilot plant level.