Topochemistry of alkaline, alkaline-peroxide and hydrotropic pretreatments of common reed to enhance enzymatic hydrolysis efficiency

Common reed was studied as raw material for sugar bioconversion. The low temperature alkaline, alkaline-peroxide and hydrotropic pretreatments were employed to overcome the recalcitrance of reed before enzymatic hydrolysis. After pretreatments, lignin was efficiently decreased from the fiber cell wall. Xylan was significantly reduced by hydrotropic pretreatment as well. The surface chemical compositions of reed before and after pretreatments were investigated by X-ray spectroscopy (XPS) and time of flight secondary ion mass spectrometry (ToF-SIMS). Reed had a high surface coverage by lignin. Hydrotropic pretreatment was outstanding to decrease the surface coverage by lignin and expose the polysaccharides to fiber surface. The surface lignin reduction was also supported by attenuated total reflectance (ATR)-FTIR results. Furthermore, the topochemical modification of the fiber wall by hydrotropic pretreatment could improve the fiber digestibility, and thus the maximum glucan and xylan yields with the cellulase dosage of 20 FPU/g raised to 93.1% and 25.5%, respectively.