Microwave-Alkaline Assisted Pretreatment of Banana Trunk for Bioethanol Production

Abstract

Pretreatment is one of the most important steps in the production bioethanol from lignocellulose materials. Alkaline pretreatment is a common mean of pretreatment but microwave oven could assist its efficiency as it can reduce the pretreatment time and improve the enzymatic activity during hydrolysis. The aim of this paper is to determine lignin removal from banana trunk using microwave-assisted alkaline (NaOH and NH 4 OH) pretreatments. The best pretreatment conditions were used for mass pretreatment before hydrolysis and fermentation. The result shows that, optimum lignin removal was with microwave-assisted NaOH pretreatment with the removal of up to 98% lignin at 2% (w/v (weight/volum)) sodium hydroxide, 170 W microwave power at 10 min. Microwave-assisted ammonium hydroxide pretreatment achieved 97% lignin removal at 1% ammonium hydroxide concentration and 680 W microwave power at 5 min. Microwave-alkaline assisted pretreatment increased the yield and quality of fermentable sugar after enzyme hydrolysis with NH 4 OH and ammonium hydroxide yielding 40% and 39% of ethanol, respectively. This result reveals that, well controlled microwave-alkaline assisted pretreatment of banana trunk could effectively remove lignin and give high bioethanol yield.