The Effect of the Addition of Acetic Acid to Aqueous Ionic Liquid Mixture Using Microwave-assisted Pretreatment in the Saccharification of Napier Grass

Napier grass, Pennisetum purpureum cv. Pakchong 1, was pretreated in an ionic liquid mixture through microwave irradiation. To improve the fermentable sugar yield, an acid catalyzed aqueous ionic liquid pretreatment was applied to maximize the total sugar conversion of pretreated Napier grass. Additionally, to optimize the fermentable sugar yield, experiments were carried out employing response surface methodology (RSM). The study showed that a maximum fermentable sugar concentration of 15.72g/L could be predicted from the model when Napier grass was pretreated by 1-ethyl-3-methylimidazolium acetate ([EMIM] [OAc]) 50% (v/v) aqueous mixture combined with 1.287% (v/v) acetic acid at a microwave pretreatment temperature and time of 147 degrees C and 76min, respectively. The experiments confirmed that the maximum sugar concentration obtained from acidic aqueous ionic liquid pretreatment were 14.38g/L under the optimal conditions. The results from the Fourier transmission infrared spectroscopic showed that an acid catalyzed aqueous ionic liquid pretreatment removed large fractions of lignin.