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In this study,1-allyl-3-methylimidazolium chloride (AMIMCl),an ionic liquid,was synthesized and characterized by a series of test methods.Pretreatment of Zoysia japonica by ammonia fiber expansion (AFEX) was shown to reduce significantly the mass of hemicellulose and lignin in biomass,thereby breaking the lignocellulosic structure.AFEX pretreatment of Z.japonica loosened the lignocellulosic matrix,weakened intermolecular forces,and destroyed intramolecular and intermolecular hydrogen bonds,causing a more open three-dimensional organization of the cellulose,lignin,and hemicellulose polymers.Z.japonica samples pretreated with AFEX showed reasonable solubility in AMIMCl upon ultrasonic treatment.Ultrasonication improved the solubility because it facilitated the penetration and diffusion of AMIMCl in the entire structure of the samples.The rate of cellulose regeneration from Z.japonica samples pretreated with AFEX increased with increase in applied power of ultrasonication within a certain power range from 0 to 110W.The regeneration rate of cellulose from AFEX-pretreated Z.japonica reached a maximum of 97% when the ultrasonic power was 110 W.At higher power,it began to decline.The subsequent decrease may be due to intensified ultrasonic cavitation caused by excess ultrasonic energy,which initiates other reactions during dissolution and leads to cellulose degradationFourier transform infrared spectroscopy and nuclear magnetic resonance analyses indicated that the regenerated cellulose was similar to microcrystalline cellulose.