Optimization of biodiesel production process for mixed Jatropha curcas–Ceiba pentandra biodiesel using response surface methodology S. Dharma a,b , H.H. Masjuki a,⇑ , Hwai Chyuan Ong a,⇑ , A.H. Sebayang a,b , A.S. Silitonga a,b , F. Kusumo a , T.M.I. Mahlia c a Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia b Department of Mechanical Engineering, Medan State Polytechnic, 20155 Medan, Indonesia c Department of Mechanical Engineering, Faculty of Engineering, Universiti Tenaga Nasional, 43000 Kajang, Selangor, Malaysia article info Article history: Received 23 December 2015 Accepted 10 February 2016 Keywords: Alternative fuel Optimization Response surface methodology Non-edible oil Biodiesel blend abstract Exploring and improvement of biodiesel production from non-edible vegetable oil is one of the effective ways to solve limited amount of traditional raw materials and their high prices. The main objective of this study is to optimize the biodiesel production process parameters (methanol-to-oil ratio, agitation speed and concentration of the potassium hydroxide catalyst) of a biodiesel derived from non-edible feedstocks, namely Jatropha curcas and Ceiba pentandra, using response surface methodology based on Box–Behnken experimental design. Based on the results, the optimum operating parameters for transesterification of the J50C50 oil mixture at 60 °C over a period of 2 h are as follows: methanol-to-oil ratio: 30%, agitation speed: 1300 rpm and catalyst concentration: 0.5 wt.%. These optimum operating parameters gives the highest yield for the J50C50 biodiesel with a value of 93.33%. The results show that there is a significant improvement in the physicochemical properties of the J50C50 biodiesel after optimization, whereby the kinematic viscosity at 40 °C, density at 15 °C, calorific value, acid value and oxidation stability is 3.950 mm 2 /s, 831.2 kg/m 3 , 40.929 MJ/kg, 0.025 mg KOH/g and 10.01 h, respectively. The physicochemical properties of the optimized J50C50 biodiesel fulfill the requirements given in the ASTM D6751 and EN14214 standards. Ó 2016 Elsevier Ltd. All rights reserved. 1. Introduction Energy is one of the basic needs in our daily lives and plays a prominent role in industrial, transportation and power generation sectors [1]. The escalating demand for fossil fuels has raised global awareness on the possibility of ‘energy crises’ due to the ongoing depletion of fossil fuels, which is made worse by the fact that fossil fuels are non-renewable sources of energy [2]. In addition, the burning of fossil fuels is a major concern for the following reasons: it releases greenhouse gases which lead to global warming and this has a detrimental impact on ecological systems in the long term, and it releases pollutants such as nitrogen oxides and unburned hydrocarbons into the atmosphere, resulting in air pollution as well as the formation of acid rain [3]. Hence, there is an urgent need to develop alternative fuels from renewable and sustainable sources such as biodiesels in order to substitute fossil fuels [4]. Biodiesels offer a number of advantages over fossil fuels since they are non-toxic, biodegradable and environmental-friendly. In addi- tion, biodiesels have high flash points and they can be blended with diesel fuels because of their similar properties [5]. Biodiesels can be produced from a variety of organic raw materials such as animal fats, vegetable oils and waste cooking oils [6–8]. Both edi- ble and non-edible vegetable oils have been shown to be prospec- tive feed stocks for biodiesel production [9]. Non-edible oils are essentially low-grade vegetable oils that have gained significance over edible oils for biodiesel production owing to the rising world population and the growing concern over food shortages [10]. Ceiba pentandra, abbreviated as C. pentandra and more com- monly known as kapok and kekabu, is a silk-cotton tree belonging to the Malvaceae family. Even though C. pentandra is native to trop- ical regions in America and West Africa, it is now found in Asian countries such as West India, Pakistan, Indonesia, Malaysia, Viet- nam and the Philippines [11–13]. Some parts of C. pentandra have high economic value since they can be used as timber whereas the pods contain 17% of fibers which can be used to manufacture pil- lows and mattresses [11]. C. pentandra is a drought-resistant plant which is naturally found in humid, tropical regions. The pods of this tree are rough, pendulous capsules containing seeds varying http://dx.doi.org/10.1016/j.enconman.2016.02.034 0196-8904/Ó 2016 Elsevier Ltd. All rights reserved. ⇑ Corresponding authors. Tel.: +60 16 590 3110; fax: +60 3 7967 5317. E-mail addresses: masjuki@um.edu.my (H.H. Masjuki), onghc@um.edu.my, ong1983@yahoo.com (H.C. Ong). Energy Conversion and Management 115 (2016) 178–190 Contents lists available at ScienceDirect Energy Conversion and Management journal homepage: www.elsevier.com/locate/enconman