Optimizing treatment condition of coir fiber with ionic liquid and subsequent enzymatic hydrolysis for future bioethanol production

Abstract

© 2017, Springer Science+Business Media B.V., part of Springer Nature.In the present study, we pretreated coir fiber with an ionic liquid (IL), n-butylammonium acetate, to expose its cellulose fibers. The best IL pretreatment conditions were determined by central composite design using a desirability function to maximize the enzymatic hydrolysis. To collect data for this optimization, coir fiber was subjected to a pulping process with 9% (w/w) sodium hydroxide for 6 h at 137 °C with a pressure of 2.5 atm. The pulping fiber was then treated with the IL for a range of times and at a range of temperatures. Based on the results, the best treatment conditions were determined to be 90 °C for 40 h. The best conditions for enzymatic hydrolysis were determined to be pH 6 at 44.16 °C for 25.57 h. Under these conditions, 32.33 ± 1.08% of the coir fiber was converted to glucose. The efficiency obtained with pulped coir fiber was 14.34 ± 0.14% and with crude coir fiber was 6.27 ± 0.15%, demonstrating the benefits of the proposed IL pretreatment.