BIODIESEL SYNTHESIS FROM WASTE COOKING OIL USING A VARIETY OF WASTE MARBLE AS HETEROGENEOUS CATALYSTS

The research article is based on biodiesel synthesis by the transesterification of waste cooking oil with methanol in the presence of heterogeneous catalysts prepared from different marble. Eight samples of marble were successfully converted into potential catalysts by calcination. The thermal treatment of waste marbles at 300 degrees C-1000 degrees C converted the metal carbonates (CaCO3) to metal oxides (CaO). The calcined marble was analyzed by chemical tests, flame atomic absorption spectroscopy (FAAS), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction studies (XRD). The presence of CaO in these catalysts made them highly reactive for biodiesel synthesis. The basicity and percentage of calcium in marble catalysts were calculated to know their basic strength. The transesterification was performed by fast stirring using waste cooking oil, methanol and nine different types of marble catalysts for 5 min at five different conditions, i.e., room temperature, hot plate stirring, solar ordinary irradiations, solar concentrated reflected irradiations and solar concentrated refracted irradiations. The solid catalysts were easily separated from the product for re-use. All marble catalysts were found to be active and basic except one namely silver pun (I). The production of biodiesel was confirmed by ASTM standards, TLC examination and by gas chromatography (GC).