ONE POT CONVERSION OF HIGH FREE FATTY ACID WASTE COOKING OIL USING A BIFUNCTIONAL CATALYST DERIVED FROM PIG BONES AND PUMPKIN STALKS: OPTIMIZATION VIA TAGUCHI APPROACH

Fatty acid alkyl esters are produced by subjecting vegetable or animal fats to a transesterification process with a low molecular weight alcohol, using a suitable catalyst. This process creates biodiesel, often referred to as 'green fuel', due to its numerous advantages such as biodegradability, renewability, reduced toxicity, higher cetane number, and flash point. Consequently, biodiesel has gained recognition as a potential substitute for conventional petroleum-based diesel (Baig and Ng 2010). In the majority of current biodiesel production methods, which employ homogeneous catalysis, refined vegetable oils serve as the primary raw materials. However, these refined oils come at a considerable expense. The cost of these feedstocks significantly affects the economic aspects of biodiesel production, as highlighted in a review conducted by Marchetti and Gebremariam, (Akhabue et al. 2020) discovered that the economics of biodiesel production are notably affected by the expense of feedstocks. Studies have indicated that the expenditure on raw materials for biodiesel production may make up as much as 88% of the total production expenses. Therefore, a substantial rduction in the production cost of biodiesel can be achieved through the utilization of non-edible oils or waste cooking oil (Haas et al. 2016). The elevated levels of free fatty acids (FFA) in waste cooking oil and various non-edible oils lead to saponification by the alkali catalyst, resulting in a r duced biodiesel yield due to the challenge of separating the product. Moreover, the purification process generates waste water, causing environmental pollution concerns, which require the treatment of waste water before disposal or reuse (Daud et al. 2015). This, in turn, adds to the cost of biodiesel production