Chemical modification of ultrasound-pretreated sugarcane bagasse with maleic anhydride

The chemical modification of sugarcane bagasse with maleic anhydride using pyridine as solvent after ultrasound pretreatment was studied. The parameters optimized included an ultrasound pretreating time of 0–35 min, a reaction time of 30–120 min, maleic anhydride concentration by the ratio of dried sugarcane bagasse to maleic anhydride from 1:0.3 to 1:1.1, and reaction temperature 85–105 °C required in the process. The extent of maleation was measured by the weight percent gain (WPG), which increased with an increment of ultrasonic pretreating time from 0 to 25 min and maleic anhydride concentration between 1:0.3 and 1:1.1. It should be noted that an increasing the temperature above 90 °C had a detrimental effect on the maleation. Evidences of maleation of the bagasse were provided by FT-IR and CP MAS 13C NMR and the results showed that the maleation of the bagasse cellulose and hemicelluloses at C-2 and C-3 occurred. Both unmodified and maleated bagasse showed a similar thermal stability above 200 °C.