Novel Ionic Liquid-Mediated Dissolution and Fractionation of Nigerian Lignocellulosic Biomass for High-Value Chemical Production

Ionic liquid-based biomass pretreatment and fractionation represent a frontier in green chemistry that holds transformative potential for converting Nigeria's vast but underutilised agricultural lignocellulosic residues into platform chemicals, biopolymers, and nanocellulose materials, yet fundamental dissolution mechanism studies and scale-up feasibility data for Nigerian biomass types are absent from the global literature. This study investigates the dissolution behaviour, fractionation efficiency, and subsequent chemical valorisation of four Nigerian lignocellulosic biomasses, specifically sugarcane bagasse, rice straw, palm empty fruit bunch, and cocoa pod husk, in a series of imidazolium, phosphonium, and cholinium-based ionic liquids. Biomass dissolution kinetics are measured by solubility experiments at varied temperatures, water content, and ionic liquid anion identity. Solid-state nuclear magnetic resonance spectroscopy, X-ray diffraction, and confocal fluorescence microscopy characterise the structural disruption of cellulose crystallinity and lignin network upon ionic liquid treatment. Selective fractionation protocols are developed to isolate cellulose, hemicellulose, and lignin streams of high chemical purity. Cellulose fractions are converted to nanocellulose by acid hydrolysis and TEMPO-mediated oxidation, and characterised by atomic force microscopy and dynamic light scattering. Lignin fractions are valorised as phenolic antioxidant additives, with performance benchmarked against butylated hydroxytoluene. Original mechanistic models of cellulose-ionic liquid hydrogen bond network disruption are developed through density functional theory calculations and molecular dynamics simulation. The study establishes the first comprehensive ionic liquid biorefinery characterisation dataset for Nigerian biomass feedstocks. Keywords: ionic liquids, lignocellulosic biomass, nanocellulose, biorefinery, green chemistry