Toward a Sustainable Production of Cellulose Nanocrystals: Benchmarking of Two Phosphoric Acid-Based Hydrolysis with Recycling Strategies and Environmental Trade-Offs

High Resolution Image Download MS PowerPoint Slide Although phosphorylated cellulose nanocrystals (P-CNCs) are promising biobased nanomaterials, their sustainable production requires hydrolysis processes that effectively balance performance, environmental impact, and economic feasibility. In this work, a phosphoric acid-derived Brønsted acidic ionic liquid (BAIL, S1 ) and conventional phosphoric acid (PA, S2 ) were compared as hydrolytic media for converting microcrystalline cellulose into P-CNCs. Experimentally, the resulting nanocrystals showed high crystallinity (>80%), nanoscale dimensions (length: 180–239 nm and width: 20–29 nm), good thermal stability (thermogravimetric analysis (TGA) T max: 329–345 °C), and negative surface charge (−24 to −30 mV). While both routes produced P-CNCs with comparable characteristics, S1 provided improved solvent recyclability. Life Cycle Assessment (LCA) and Techno-Economic Analysis (TEA) of pilot-scale projections indicated that the BAIL-based ( S1 ) process is a promising alternative, with economic performance mainly influenced by solvent costs and solid–liquid separation requirements. Nevertheless, solvent recovery and recycling significantly reduce both environmental burdens and process costs. Overall, BAIL-mediated hydrolysis emerges as a sustainable and scalable alternative to conventional PA-based production of phosphorylated CNCs.