One-step production and physicochemical characterization of biodiesel using rubber seed oil blends

Abstract The seeds of Hevea brasiliensis (HB) stand out as a promising feedstock for biodiesel production owing to their high oil content. However, its elevated acid value poses a challenge, requiring pre-treatment steps before transesterification. Given this scenario, the present study aimed to evaluate the feasibility of producing biodiesel from blends of HB oil with lower-acidity vegetable oils, namely soybean, corn, canola and sunflower oils, at volume concentrations of 1%, 3%, 5%, 10%, 15% and 20% HB oil. Biodiesel was produced via base-catalysed transesterification using 1–2 wt% potassium hydroxide (KOH) as catalyst. Biodiesel meeting the required quality standards was obtained with up to 20% HB oil in canola oil blends, 3% HB oil in soybean and sunflower oil blends and 5% HB oil in corn oil blends. These optimal blends showed acid values of 18.79, 3.73, 2.70 and 5.27 mg KOH g−1, respectively. The physicochemical properties of the produced biodiesel were analysed and compared with the standards established by the ANP, EN 14214 and ASTM D6751. Particular emphasis was placed on the ester content (fatty acid methyl ester, FAME), which exceeded 96.5% conversion in all cases.