Abstract
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•Microwave-IL-acidic resin for 5-HMF synthesis from pretreated bagasse introduced.•Optimum conditions for 5-HMF synthesis：[Bmim]OAc, D001-cc, 140 ℃ and 25 min.•Bagasse pretreated with [Bmim]OAc/ultrasound at 40 kHz/30 min showed 65.72 % 5-HMF.•Pretreated bagasse are higher than the untreated by 39.73–165.43 % 5-HMF yields.
This work aimed at investigating the synthesis of 5-HMF from the ultrasound-ionic liquid pretreated sugarcane bagasse in a microwave-solid acid-ionic liquid system. The XRD analysis indicated that the macrostructure of cellulose remained intact after the ultrasound-ionic pretreatment, [Bmim]OAc showed better performance than [Bmim]Cl. The best conditions for the untreated bagasse conversion to 5-HMF were [Bmim]OAc, ion-exchange resin catalyst, D001-cc, 140 ℃ and 25 min. The ultrasound-ionic liquid pretreatment at different frequencies (20–50 kHz) increased the 5-HMF yield by 39.73–165.43 % compared with that of the untreated bagasse, indicating the role of the acoustic cavitation in enhancing the transformation of bagasse into 5-HMF. The bagasse pretreated with [Bmim]OAc/ultrasound at 40 kHz/30 min showed the highest yield of 5-HMF (65.72 %). The synthesis of 5-HMF from the pretreated sugarcane bagasse in the microwave-solid acid/ionic liquid system could be a promising channel for production of biofuels and related chemicals.