Investigation on the utilization possibilities of industrial waste fats and oils in biodiesel production

In this thesis, the use of different types of waste oils in biodiesel production and the effects of natural antioxidants on improving biodiesel stability were investigated. Biodiesel was produced using waste oils such as sunflower oil, safflower oil and margarine oil. Based on the analysis of crude oils, sunflower oil contained 62.06% linoleic acid and 26.80% oleic acid; safflower oil had 75.55% linoleic acid and 14.88% oleic acid; and margarine oil had 23.94% palmitic acid and 42.40% oleic acid. The densities of the crude oils were measured as 0.921 g/mL for sunflower oil, 0.924 g/mL for safflower oil, and 0.914 g/mL for margarine oil. In the characterization of the produced biodiesels, the water content was determined as 0.041 ppm in sunflower oil biodiesel, 0.045 ppm in safflower oil biodiesel, and 0.059 ppm in margarine oil biodiesel. The densities of the biodiesels were found to be 883.1 g/mL, 880.4 g/mL, and 892.6 g/mL, respectively. The iodine number was measured as 127 for sunflower oil biodiesel, 139 for safflower oil biodiesel, and 53 for margarine oil biodiesel. The viscosity values were 4.193 mm²/s for sunflower oil biodiesel, 4.216 mm²/s for safflower oil biodiesel, and 4.422 mm²/s for margarine oil biodiesel. Natural antioxidants such as green tea, olive leaf and turmeric contributed to extending the shelf life of biodiesel by enhancing its oxidative stability. Among all samples, turmeric increased biodiesel stability by approximately 1.8 times. It was determined that, biodiesels produced from waste oils largely complied with the EN 14214 biodiesel standards, achieving significant results in terms of environmental sustainability. The optimal use of natural antioxidant substances is recommended to reduce biodiesel production costs and enhance its environmental benefits.