Abstract:

The paper presented a method for the pretreatment of bamboo wood with AlCl₃ assisted eutectic solvent(DES). The DES was synthesized using choline chloride and AlCl₃ as the hydrogen acceptors, and guaiacol used as the hydrogen donors. The effects of AlCl₃ dosage in DES on the chemical composition and subsequent enzymatic hydrolysis efficiency of the pretreated bamboo were investigated. The results showed that with the increase of AlCl₃ dosage, the contents of xylan and lignin decreased gradually with the content of glucan increased in pretreated bamboo, which significantly improved its enzymatic hydrolysis efficiency. Under optimal conditions(the amount of choline chloride, guaiacol and AlCl₃ was 25∶50∶1). The conversion rate was 42.84%, the recovery of glucan and xylan were 95.95% and 12.84%, respectively, with 74.88% lignin removal. Compared with the DES treatment without the addition of AlCl₃, glucan enzymatic hydrolysis with AlCl₃-assisted DES treatment increased from 11.16% to 96.20%. The results demonstrated that AlCl₃ could effectively promote the dissolution of xylan and lignin. The pretreated materials were characterized by XRD, SEM, and FT-IR. XRD analysis showed that with the increase of AlCl₃ dosage, the crystallinity of the pretreated materials increased gradually, mainly due to the gradual removal of lignin and xylan components, while the cellulose components were not significantly damaged. SEM analysis showed that after pretreatment, the pretreated materials appeared obviously fragmentation and agglomeration. With the increase of AlCl₃ dosage, the bamboo components were gradually dissolved and destroyed. The FT-IR analysis results also proved that the increase of cellulose content in the pretreated materials accompanied by the gradual decrease of xylan and lignin.

Key words: AlCl₃, DES, moso-bamboo, enzymatic hydrolysis