Int. Journal of Renewable Energy Development 10 (4) 2021: 803-810 Page | IJRED-ISSN: 2252-4940. Copyright © 2021. The Authors. Published by CBIORE 803 Athar Contents list available at IJRED website Int. Journal of Renewable Energy Development (IJRED) Journal homepage: http://ejournal.undip.ac.id/index.php/ijred Experimental Investigation and Optimization of Non-Catalytic In-Situ Biodiesel Production from Rice Bran Using Response Surface Methodology Historical Data Design Siti Zullaikah a,* , Ari Krisna Putra a , Fathi Haqqani Fachrudin a , Adi Tjipto Utomo a , Rosada Y. Naulina a , Sri Utami a , Rifky P. Herminanto a , Yi Hsu Ju b,c,d a Department of Chemical Engineering, Institut Teknologi Sepuluh Nopember (ITS), Kampus ITS Keputih Sukolilo, Surabaya 60111, Indonesia b Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, Taiwan c Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan d Taiwan Building Technology Center, National Taiwan University of Science and Technology, Taipei, Taiwan ABSTRACT. Rice bran oil (RBO) is claimed to be a potential feedstock for biodiesel production. Non-catalytic in-situ biodiesel production from a low-cost feedstock (rice bran) using subcritical ethanol-water mixture was investigated in this study. The influence of four independent variables, i.e., addition of co-solvent, ethanol concentration, temperature, and time of reactions, on the yield of biodiesel was examined. The results showed that the most effective co-solvent was ethyl acetate and the optimum ethanol concentration, temperature and reaction time were 80% v/v, 200 o C and 3 hours, respectively. The maximum yield of biodiesel was found to be around 80%. The optimization of operating conditions was carried out by response surface methodology (RSM) with historical data design (HDD). The statistical method also suggested similar optimum operating conditions, i.e., 78.44% (v/v) ethanol concentration, 200 o C, and 3.2 hours reaction time with ethyl acetate as a co-solvent. The predicted maximum biodiesel yield was also slightly lower, i.e., 76.98%. Therefore, this study suggests that biodiesel production from rice bran through a non-catalytic in-situ process using a subcritical ethanol-water mixture with ethyl acetate as a co-solvent is very feasible since the yield can reach 80%. The study also found that RSM with HDD can predict the optimum operating conditions with a good accuracy. Keywords: Rice bran; Biodiesel; Historical data design; Subcritical ethanol-water mixture Article History: Received: 13 th Nov 2020; Revised: 25 th Jan 2021; Accepted: 11 th June 2021; Available online: 20 th June 2021 How to Cite This Article: Zullaikah, S, Putra, A.K. Fachrudin, F.H., Naulina, R.Y., Utami, S., Herminanto, R.P., Ju, Y.H. (2021)Experimental Investigation and Optimization of Non-Catalytic In-Situ Biodiesel Production from Rice Bran Using Response Surface Methodology Historical Data Design Int. Journal of Renewable Energy Development, 10(4), 804-810 https://doi.org/10.14710/ijred.2021.34138 1. Introduction Dependence on fossil fuels is an important concern nowadays. In Indonesia, the country with the 4 th largest population in the world, the consumption of petroleum was recorded at 1,785,000 barrels/day while the production of petroleum was only 778,000 barrels/day in 2019 (British Petroleum 2019, Dewan Energi Nasional 2019). The consumption of fossil fuels is also proven to be the main cause of climate change due to the emission of greenhouse gases into the atmosphere (Syafiuddin et al. 2020). Therefore, an environmental- friendly alternative fuel is required to replace conventional fossil fuels. Biodiesel is an environmental-friendly fuel that is suitable to replace conventional diesel fuels since it is easily biodegradable in nature, non-toxic, and has low * Corresponding author: szulle@chem-eng.its.ac.id sulfur and aromatic contents (Syafiuddin et al. 2020, Jahirul et al. 2021). In addition, biodiesel has high fuel efficiency, low emissions, and can be used as fuel in diesel engines without modifications (Sundar & Udayakumar, 2020, Bathia et al. 2021). However, there are still obstacles in the production process of biodiesel, including a long process stage and uneconomical feedstock (Zullaikah et al. 2017, Zullaikah et al. 2019). Rice bran is an alternative feedstock for biodiesel production since it has high lipid content between 15-23 wt.%, depending on the rice type and degree of milling (Nguyen et al. 2019, Chen et al. 2020). However, rice bran oil (RBO) is significantly higher in free fatty acids (FFA) content than other edible oils due to the presence of an active lipase. Hence, 60-70% of the global production of RBO is used in non-food applications. Therefore, RBO is a Research Article