Biodiesel production from microalgal biomass using CaO catalyst synthesized from natural waste material

Calcium oxide (CaO) catalyst was prepared using chicken egg shell waste and tested as a catalyst for the production of biodiesel from Chlorella vulgaris biomass. The calcination method was adopted for the synthesis of CaO catalyst. Transmission electron microscope (TEM) image showed that the catalyst had a spherical structure with average particle size of 46.1 +/- 2.1 nm, further analysis was carried out using Brunauer-Emmett-Teller (BET) adsorption, scanning electron microscopy, elemental analysis, X-ray diffraction and Fourier-transform infrared spectroscopy. Transesterification process was conducted by using response surface methodology (RSM) based on central composite design (CCD). The optimum reaction conditions were observed at 70 degrees C, 10:1 methanol: dry biomass ratio, 1.39% catalyst loading, 3 h reaction time, and 140 rpm stirring rate resulted 92.03% biodiesel yield. The key fuel properties includes; iodine value (88.5 g I-2 100/g), cetane number (50.0), cloud point (9.2 degrees C), pour point (3.1 degrees C), oxidation stability (7.4 h), higher heating value (44.7), kinematic viscosity (4.5 mm(2)/s) and density (0.9 g/cm(3)) resulted good quality of microalgae biodiesel. Our research finding shows that the CaO catalyst derived from egg shell waste is an economically potential and eco-friendly catalyst for biodiesel production. (C) 2019 Elsevier Ltd. All rights reserved.