Hydrolysis kinetics of inulin by imidazole-based acidic ionic liquid in aqueous media and bioethanol fermentation

•A potentially environment-friendly technology was developed to produce ethanol.•Hydrolysis rate by ILs in water media was higher than by dilute sulfuric acid.•A concise kinetic model of inulin hydrolysis by ILs was firstly proposed.•The kinetic model predicted well the inulin hydrolysis by ILs.•Conversion efficiency of inulin-type sugars to ethanol reached 94.21%.

This article focused on the inulin-containing energy biomass, Jerusalem artichoke, to explore environment-friendly processes for bioethanol production. An imidazole-based acidic ionic liquid (VImaILs) was prepared as the catalyst of inulin hydrolysis in aqueous media. The hydrolysis kinetics was studied under different conditions. The kinetic parameters of hydrolysis by VImaILs and dilute sulfuric acid were estimated and compared. This work demonstrated that the hydrolysis rate of inulin into reducing sugars by VImaILs was obviously faster than that by the latter. The proposed kinetic model successfully predicted the inulin hydrolysis in wider ranges of experimental conditions. The hydrolysate was fermented into ethanol by Saccharomyces cerevisiae which activity was not inhibited by the VImaILs. The conversion efficiency of inulin-type sugars to ethanol was greater than 92.5% of the theoretical yield. And the ethanol production capacity reached 123.76 g/(L). This system integrated the chemical and biological processes to prepare ethanol in an environment-friendly way.

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