Abiding effects of phenolic antioxidants on oxidative behaviour of fatty acid methyl esters derived from waste cooking oil

Fatty acid alkyl esters (FAMEs) derived from waste vegetable oils and non-edible oil sources are the most attractive alternative liquid biofuel in the energy field. Substitute methyl esters derived from waste cooking oil (WCO) have a lower induction period (3.12 h) and do not satisfy the Biodiesel EN 14214:2012 Standard (8 h). In this study, concentrations of 100, 250, 500, and 1000 ppm of four different types of phenolic antioxidants—butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), tert-butyl hydroquinone (TBHQ), and propyl gallate (PG)—were used to examine oxidative stability and improve fuel quality. PG (250 ppm) showed the most effective result of 18 h to 12.17 h of the induction period of 6 months of storage. Antioxidant effectiveness increased with regard the oxidative stability of waste cooking oil methyl ester in the following order: BHT