Production of biodiesel from dairy waste scum using eggshell waste

An effluent from the dairy industry, waste scum oil containing triglycerides of fatty acids from C-4-C-18 was selected as a potential feedstock for biodiesel production in the presence of nano calcium oxide obtained from modified eggshell. The eggshell waste was calcined at 800 degrees C to facile synthesize nano calcium oxide and was characterized by X-ray diffractometer (XRD), Fourier Transform Infrared spectrometer (FTIR) and Scanning Electron Microscope (SEM). The calcined eggshell contains mainly nano calcium oxide (CaO) in calcite form with the crystallite size ranging from 16 to 22 nm. The transesterification reaction was carried out in a batch reactor and the operating parameters like catalyst loading, the molar ratio of methanol: oil, reaction temperature and time were optimized. Maximum biodiesel yield of 96% was obtained at the molar ratio of methanol: oil of 6:1, catalyst amount of 2.4 wt% and the reaction temperature of 65 degrees C for 3 h. The quality of biodiesel produced by transesterification of dairy waste scum was tested on variable four-stroke compressible diesel engine and found to be comparable with conventional diesel in brake thermal efficiency and specific fuel consumption. The biodiesel produced possessed high cetane number and low NOx, than conventional diesel. The results proved that nano CaO obtained from eggshell can be effectively reused and recycled as a heterogeneous catalyst for biodiesel production. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.