Pilot-Scale Production of Nanolignin: Challenges and Case Studies

Nanolignin represents a rapidly emerging class of biobased materials derived from one of the most abundant renewable polymers. Unlike conventional materials with fixed composition, nanolignin is inherently process-defined, with structure, morphology, and functionality governed by lignin chemistry, feedstock origin, extraction method, and particle formation pathway. This review provides a comprehensive analysis of nanolignin, covering major technical lignins (kraft, soda, lignosulfonate, organosolv, ionoSolv, and deep eutectic solvent-derived) and their influence on particle formation. Key synthesis routes, including solvent-shifting, pH-induced precipitation, aerosol processing, microfluidics, and aqueous methods, are discussed alongside the mechanistic principles that control nucleation, growth, and morphology. A critical focus is placed on scaling from laboratory to pilot production. Challenges such as mixing and supersaturation control, heat and mass transfer, solvent recovery, fouling, and feedstock variability are evaluated through representative case studies, highlighting transferable design principles and persistent bottlenecks. Techno-economic considerations are integrated to assess industrial feasibility, emphasizing process integration, solvent management, and energy efficiency. Finally, structure-property-function relationships are linked to key applications, including polymer nanocomposites, coatings, UV stabilization, and emulsification.