Waste Cooking Oil Characteristics

Results and discussion

Waste Cooking Oil characteristics
The physicochemical properties of oil are shown in Table 1. The acid value (AV) of WCO was 2.15 mg KOH g-1, whereas it had 12.6% of free fatty acid (FFA). The saponification value and density were 191 mg KOH g-1 and 0.915 g cm-3, respectively. Therefore, the average molecular weight of WCO was calculated as 409.84 g mol-1.

TGA/DTA Analysis
Fig.1 shows the TGA/DTA curves of the metal oxide catalyst precursor before calcination. The DTA peak has a closer correspondence with the weight changes observed on the TGA curves. The decomposition occurred mainly via two distinct stages as depicted by all the curves and was complete at about 800°C. The weight loss at 697–768ºC corresponds to the loss of CO2 by the decomposition of calcium carbonate in the precursor to form CaO phase which reacts with other active ingredient CeO2 to form CaO-CeO2.

Fig.1 TGA/DTA spectra of the bimetallic oxide (CaO-CeO2) catalyst.

Structure and crystallography
Fig. 2(a), (b), (c) show the powder XRD patterns of the CaO, CeO2 and CaO–CeO2 catalysts system. The well-defined and narrow crystalline diffraction peaks was

2) gave the formation of cubic fluorite-type CeO2 phase and cubic CaO in a binary metal system. The XRD profile of the CaO–CeO2 mixed catalysts revealed the characteristic peaks of crystalline phases of their separate metal oxide without the new mixed oxide phases formation (homogeneous mixed solid phases) detectable in the particles. The major reason was difference in ionic radii of the metal ions.7 The CaO phase was found to have a low peak intensity, whereas cubic fluorite-type structure of CeO2 was associated with the strong reflection in the XRD profile. In bimetallic oxide catalyst, the XRD peaks become more intense for cubic CaO phase, and concomitantly those associated with CeO2 phase decrease significantly. This was mainly due to the higher X-ray scattering factor of Ca2+ with that of Ce4+