Understanding changes in hydrolyzability and lignin performance of Camellia oleifera shell in milder tetrahydro-2-furanmethanol/ferric chloride system

Camellia oleifera Able shell presents abundant annual production but lacks effective and comprehensive valorization techniques. The aim of this study was to develop a promising pretreatment method for achieving comprehensive utilization of Camellia oleifera Able shell. Pretreatment of ethanol-extracted Camellia oleifera shells (ECOS) was proposed using tetrahydro-2-furanmethanol (THFA) at 170 °C with no holding time and 0.037 mol/L FeCl3, achieving 93 % cellulose recovery and 85 % lignin removal. The pretreated ECOS surface became fragmentary with lower negative charges and higher thermal stability. The specific surface area of the pretreated ECOS increased by 24.6 times to 6.15 m2/g, correspondingly, the glucose yield rose by 5.0 times than that of untreated ECOS. Addition of PEG10000 promoted the high-solids fed-batch enzymolysis of pretreated ECOS, yielding 95 g/L glucose concentration in the hydrolysate at 15 % solid with 5 FPU/g. Furthermore, this pretreatment effectively deconstructed the natural lignin-carbohydrate complex, while simultaneously removing substantial quantities of acetyl groups. The recovered lignin fragments exhibited excellent enhancement in terms of high UV absorption capacity and fluorescence intensity. The THFA-FeCl3 pretreatment demonstrated significant potential for the production of fermentable sugars and high-performance lignin from highly lignified biomass.