Effect of Dilute Acid and Alkaline Pretreatments on Enzymatic Saccharfication of Palm Tree Trunk Waste for Bioethanol Production

*Kusmiyati Kusmiyati -  Dept. of Industrial Engineering, Universitas Dian Nuswantoro , Semarang, Indonesia
Sakina Tunissa Anarki -  Departement of Chemical Engineering, Faculty of Engineering, Muhammadiyah University of Surakarta , Jl. A. Yani Tromol Pos 1, Pabelan, Kartasura 57102, Surakarta, Indonesia
Sabda Wahyu Nugroho -  Departement of Chemical Engineering, Faculty of Engineering, Muhammadiyah University of Surakarta , Jl. A. Yani Tromol Pos 1, Pabelan, Kartasura 57102, Surakarta, Indonesia
Reistu Widiastutik -  Departement of Chemical Engineering, Faculty of Engineering, Muhammadiyah University of Surakarta , Jl. A. Yani Tromol Pos 1, Pabelan, Kartasura 57102, Surakarta, Indonesia
Hadiyanto Hadiyanto -  Department of Chemical Engineering, Diponegoro University, Indonesia
Received: 25 Jan 2019; Revised: 2 Jul 2019; Accepted: 15 Jul 2019; Published: 15 Dec 2019; Available online: 30 Sep 2019.
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Section: The 3rd International Conference on Chemical and Material Engineering 2018 (ICCME 2018)
Language: EN
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Abstract

Increasing energy demand, rising prices of crude oil, and security issues regarding oil supply are the aspects that underlay research about development of alternative energy. Arenga pinnata (or palm trees) is one of lignocellulosic biomass which is non-food plant, high cellulose content, and abundant in Indonesia which recognized as having great potential for bioethanol production. However lignins present can inhibit the action of enzyme at saccharification process, so that pretreatment plays an important role to degrade lignin and increase the number of cellulose which will convert to ethanol. The effect of pretreatment of the substrate using nitric acid (HNO3), ammonium hydroxide (NH4OH) each at 2%, 4%, 8%, and 10% (v/v) concentration, and steam pretreatment to reducing sugar and ethanol content were investigated. The pretreated samples was hydrolyzed using cellulase enzyme with substrate concentration 10% (w/v) for 24 h, 48 h, 72 h at 50°C and pH 5.0. Results from the enzymatic saccharification experiments showed that maximum reducing sugar and total sugar content of palm tree trunk waste pretreated using 10% (v/v) of HNO3 are 5.320% and 5.834% was achieved respectively at 72 h of saccharification. While the maximum reducing sugar and total sugar content of palm tree trunk waste pretreated using 10% (v/v) of NH4OH are 2.892% and 3.556% respectively at 72 h of saccharification. Steam pretreatment shown the maximum reducing sugar and total sugar respectively 1.140% and 1.315% at 72 h of saccharification. It shown that pretreatment using nitric acid (HNO3) give the maximum results of reducing sugar and total sugar compared to others. The SSF process was carried out at 37°C, pH 4.8, and 100 rpm for 120 h using Saccharomyces cerevisiae and cellulase enzyme with 10% (v/v) of yeast concentration and 10% (w/v) of substrate concentration. The result shows that the highest ethanol content can be produced by a high concentration of substrate where the highest ethanol content was 2.648% by using HNO3 10% (v/v) compared to NH4OH 10% (v/v) that produced 0.869% and steam pretreatment that produce 0.102% ethanol content. This demonstrates the utility of palm tree trunk wastes in ethanol production.

Keywords
Bioethanol; lignocellulose; substrate concentration; dilute acid pretreatment; alkaline pretreatment; SSF

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