Abstract: Carboxylation of unprocessed sugarcane bagasse with succinic anhydride under ultrasound irradiation was studied. The effects of ultrasound-irradiating time,reaction time, reaction temperature, and anhydride dosage on the reaction were discussed. The extent of carboxylation was measured by the weight percent gain (WPG). FT-IR spectra of unmodified and carboxylated bagasse were also used to characterize the effects of experimental conditions on carboxylation. The results showed that modification of bagasse with succinic anhydride is an efficient method for preparation of products containing carboxylic groups. Increases of reaction time, anhydride dosage, and reaction temperature led to increment of WPG under given experimental conditions. A WPG of 39.4% was achieved under the condition of ultrasound-irradiation time 30 min, reaction time 60 min, succinic anhydride dosage by the ratio of anhydride to dried bagasse 1.25:1, and reaction temperature 115℃. The samples were also characterized by CP/MAS ¹³C NMR spectroscopy. It was found that during treatment of sugarcane bagasse with succinic anhydride under the conditions used, both polysaccharide and lignin participated the reaction. The crystallinity indexes of cellulose in sugarcane bagasse decreased after chemical modification.

Key words: sugarcane bagasse, succinic anhydride, carboxylation