Optimizing treatment condition of coir fiber with ionic liquid and subsequent enzymatic hydrolysis for future bioethanol production
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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.
KeywordsLignocellulosic residue Coir fiber Ionic liquids pretreatment Enzymatic hydrolysis Central composite rotatable design with two center points
We are grateful to Fundação Educacional Inaciana Padre Sabóia de Medeiros (FEI) for supporting this research. We thank Dr. Nivaldo Boralle from the Chemical Institute of UNESP for the NMR measurements.
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