Effective fractionation and valorization of Camellia oleifera fruit shells under the concept of lignocellulosic biorefinery

Camellia oleifera fruit shells (CFS), a by-product of Camellia oleifera oil production industry, are rich in hemicellulose and lignin components. In this work, efficient fractionation and valorization of CFS were investigated. Malic acid (MA) pretreatment (6 g/L MA, 5 g/L 2-naphthol (2 N), 160 ℃, 30 min) resulted in a maximum yield of XOSs of 73.3 %. Besides, alkaline hydrogen peroxide/ethanol (AHP/E) biphasic delignification at mild conditions extracted over 90 % lignin from the MA2N pretreated solid, which was fabricated as lignin nanoparticles (around 170 nm) for drug delivery. Finally, the MA2N-AHP/E combinational pretreatment provided a cellulose-enriched residue, with cellulose retention rate of 93.1 %, which was enzymatically converted to glucose with nearly 100 % hydrolysis efficiency. Results revealed that the combinational pretreatment was an ideal first step of lignocellulosic biorefinery using CFS as feedstock for co-production of XOSs, fermentable sugars and lignin nanocarriers, which potentially alleviated environmental problems caused by discarding, burning and composting of CFS.