Fuel stability of biodiesel from waste cooking oil: A comparative evaluation with various antioxidants using FT-IR and DSC techniques

Valorization of waste for biodiesel production is an important parameter as 75% of biodiesel production cost comes from the feedstock cost itself. Therefore, waste cooking oil appears as one of the best accessible option for biodiesel production globally given its availability and low price. On the other hand, fuel stability is one of the most critical properties related to the commercialization of biodiesel into the global fuel market. Doping of synthetic antioxidants is a convenient method for enhancing the stability of biodiesel. Recent studies investigate the effect of antioxidant addition on fuel stability at different concentrations. In this study, three synthetic antioxidants namely; Pyrogallol (PY), Butylated hydroxytoluene (BHT) and Tert-Butylhydroquinone (TBHQ) were dosed into waste cooking biodiesel at different concentrations ranging from 375, 750, 1000, 1125, 1500 ppm respectively for enhancement of the fuel stability. This was followed by assessing the stability of the samples by means of fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC) instead of conventional Rancimat method. The findings indicated the effectiveness of FT-IR and DSC as reliable methods to assess the oxidation stability and to replace the conventional, time-consuming and costly Rancimat method. TBHQ was found to be the best option to enhance the stability of biodiesel. These findings are in agreement with the existing literature. The current study proved the effectiveness of both FT-IR and DSC methods as cheap, fast and reliable methods and thus can be considered as reliable methods for determination of oxidation stability of biodiesel.