The aim of this study was to analyze the catalytic performance of sea sand as a nonconventional catalyst
in the transesterification reaction of used cooking oil and refined oil with methanol. The sea sand was
utilized as a source of calcium oxide. The main characteristic of this sea sand is the high content of CaCO3
which was transformed into CaO by calcination. The catalyst was characterized by X-ray diffraction
(XRD), scanning electron microscopy (SEM), nitrogen adsorption/desorption (BET) and by Hammett
method (basicity determination). The produced biodiesel has 95.4% (polar + non polar methyl esters),
96.6% and 97.5% methyl esters content when employing used cooking oil, safflower oil and soybean
oil, respectively. The obtained biodiesel at these conditions (atmospheric pressure, reaction temperature
of 60 C, 12:1 M ratio of methanol:oil and catalyst amount of 7.5%) met key parameters (viscosity:
4.2–5.0 mm2/s and acid value: 0.05–0.011 mg KOH/g) of the European norm EN-14214 (viscosity:
3.5–5.0 mm2/g and acid value: max. 0.50 mg KOH/g).