Catalytic effect of metals on thermal stability of olive oils

Abstract

The catalytic effect at homogenous phase of several metals on the thermal stability of olive oils of different characteristics has been studied. Samples were prepared by dissolution of suitable amounts of organo-metallic compounds in the oils, to obtain concentrations of metal between 0–30 ppm. The compounds organo-metallic were: ferrocene (Fe-II), dibutyltin diacetate (Sn-II), copper acetylacetonate (Cu-II) and lead acetate (Pb-IV). The study was carried out by applying thermal analysis techniques: thermogravimetry (TG) and derivative thermogravimetry (DTG). The obtained results show that the degradation rate of the oil is always higher in the presence of metals and its value is as greater as higher is concentrations. On the other hand, the kinetic parameters of the thermodegradation reaction of the oil, activation energy a n d f requency factor, w ere deter mined from thermogravimetric data. The obtained values for both parameters confirm the negative influence of the tested metals on the oil thermal stability. This effect is more evident for lead, followed of iron and tin and finally copper. Likewise, the results of thermal analysis allow to define the order of thermal stability of oils of different origins and refined grades.

Keywords

• activation energy
• degradation rate
• metal catalysis
• olive oil
• thermal analysis
• thermal stability