Synthesis of biodiesel from low FFA waste frying oil using calcium oxide derived from Mereterix mereterix as a heterogeneous catalyst

Biodiesel was produced from waste frying oil (WFO) using powdered calcined clamshell (Mereterix mereterix) as a heterogeneous catalyst. Clamshell calcined at 1173 K for 2.5 and 3.5 h showed different catalytic activities. Calcination for 3.5 h resulted in a catalyst of higher activity and reduced trans-esterification reaction time. The raw and calcined clamshells were characterized by XRD, FIR. XRF spectroscopy and BET analysis. The XRD peaks showed the characteristics peaks of CaO at 2 theta = 37.4, 47.3, and 54.4 degrees. A few high intensity peaks of Ca(OH)(2) at 2 theta = 17.9 and 34.1 degrees in the calcined catalyst were also obtained which might have formed due to exposure of CaO with atmospheric air. The used catalyst showed peaks at 8.2 and 10.1 degrees which were characteristic of calcium glyceroxide which was formed due to reaction of calcium oxide and glycerol. Formation of Ca(OH)(2) in the calcined clamshell was also confirmed by FTIR spectra which showed a sharp OH- stretching band. The catalyst was found to comprise principally of calcium (97%) and a few minor elements (Si, Na, Fe, Al, Sr, S. Mn) as analyzed by XRF. The surface area of the calcined clamshell was found to be 2.6 m(2) g(-1). The optimum values for various parameters were found to be 3.0 g of catalyst and 25 ml of methanol per 100 ml of oil (6.03:1, methanol to oil molar ratio) at 333 K in 3 h. A high yield (>89%) and conversion (>97%) were obtained on optimization of variables. With the mandatory compulsion by National Biofuel Policy in India to blend 20% of biofuels i.e. bioethanol and biodiesel in the spark ignition and compression ignition engines respectively from 2017 strengthens the applicability of the present study that utilizes waste resources as feedstock and catalyst in the production of a green fuel i.e. biodiesel. (C) 2012 Elsevier Ltd. All rights reserved.