Development of heterogeneous alkali catalyst from waste chicken eggshell for biodiesel production Jibril Goli a, * , Omprakash Sahu b a Department of Chemical Engineering, Adama Science & Technology University, Adama, Ethiopia b School of Civil Engineering, Ethiopian Institute of Technology, Mekelle University, Mekelle, Ethiopia article info Article history: Received 20 February 2017 Received in revised form 13 May 2018 Accepted 14 May 2018 Available online 15 May 2018 Keywords: Alkali catalyst Calcium oxide Eggshell Process optimization Transesterification abstract In this research work, heterogeneous alkali catalyst was derived from low-cost chicken eggshell waste. Among the catalyst synthesis route, calcinations method was used to decompose the calcium carbonate present in the waste. The synthesized catalyst was characterized by TGA/DTA, powder XRD, XRF, FT-IR, and SEM analytical instrument. In an effort to optimize the reaction condition of biodiesel production from soybean oil, a response surface methodology-Box-Behnken method was used. The maximum biodiesel yield of 93% and 92.32%; experimental and predicted respectively was obtained at a reaction temperature of 57.5  C, reaction time of 3 h, methanol to oil molar ratio of 10:1, catalyst concentration of 7 wt%. The experiment was carried out in the three-necked batch-glass reactor at atmospheric pressure. Finally, the fuel properties of obtained biodiesel were measured and were all in the standard range. © 2018 Elsevier Ltd. All rights reserved. 1. Introduction Due to rapid population growth and industrial development, the worldwide energy consumption is increasing day by day [1]. Some alternative energy sources such as solar, hydrogen, wind and bio- diesel have attracted the attention of researcher to fulfill the de- mand [2]. Among these renewable sources, biodiesel is considered as a prominent alternative fuel as it is nontoxic, biodegradable, renewable and environmentally friendly energy source [3]. Trans- esterification reaction of vegetable oil or animal fats with methanol in the presence of catalyst gives biodiesel. At mild reaction tem- perature, short reaction time and atmospheric pressure; high bio- diesel yield are obtained by using homogeneous alkali catalyst in the transesterification process [4]. However, emulsification, more consumption of energy, separation of the catalyst after reaction and generation of excess waste water are the major problem associated with this type of catalysts [5]. These issues can be addressed by developing heterogeneous catalysts [6]. However, due to diffusion problem owing to the formation of three phases of the reactants; methanol-oil-solid catalyst, heterogeneous catalytic reactions are usually time-consuming [7]. Therefore, it is difficult to identify a solid base catalyst for transesterification process under mild reac- tion conditions and short reaction time [8]. Alkaline earth metal oxides with high basicity are appropriate to use for biodiesel pro- duction. The alkaline earth metal oxides, calcium oxide are one of the most promising heterogeneous basic catalysts used for bio- diesel production [9]. Availability of calcium oxide has been re- ported in different types low cost materials like waste egg shell, waste fish scale, waste cockle shell, waste mud scrub shell and waste animal bone and used for the production of biodiesel from variety of oils such as soybean oil, palm oil, waste cooking oil and canolla oil [10]. Out of these chicken egg shell (CSE) is abundantly available as chicken eggs are part of the daily meal in most of the countries. Calcium carbonate is the major constituent of chicken eggshell (approx. 96% of the oxides), which occurs naturally in the form of calcite [11]. Application of waste egg shell as raw material for the synthesis of catalyst eliminates the wastes and simultaneously produces the heterogeneous alkali catalyst with high-cost effec- tiveness. The use of chicken eggshell waste as a catalytic material is one way to keep the environment clean [12]. This approach creates additional revenue opportunities for entrepreneur and local gov- ernment in addition to reducing the cost of procuring and syn- thesizing the catalytic material. In literature several advantage of using chicken egg shell based heterogeneous catalyst are, discussed like high yield of biodiesel [13]; low soluble of catalyst [14]; easy to * Corresponding author. E-mail address: jibrilgoli430@gmail.com (J. Goli). Contents lists available at ScienceDirect Renewable Energy journal homepage: www.elsevier.com/locate/renene https://doi.org/10.1016/j.renene.2018.05.048 0960-1481/© 2018 Elsevier Ltd. All rights reserved. Renewable Energy 128 (2018) 142e154