Utilization of Microwave Technology in the Esterification Process of Nyamplung Oil (Calophyllum inophyllum L.) for Biofuel Feedstock

Abstract

Indonesia’s national energy demand remains heavily reliant on fossil fuels such as petroleum, natural gas, and coal. This dependency raises serious concerns regarding the long-term availability of energy reserves and contributes significantly to environmental degradation due to high greenhouse gas emissions. Consequently, the development of renewable energy sources has become crucial in achieving sustainable national energy security. One promising renewable energy alternative is biodiesel, particularly from non-edible oil sources like nyamplung seed oil (Calophyllum inophyllum). This study aims to evaluate the potential of nyamplung oil as a biodiesel feedstock through esterification using microwave-assisted heating technology, which offers advantages in accelerating chemical reactions and improving energy efficiency. The process begins with degumming using 85% phosphoric acid (H₃PO₄) to remove impurities such as phospholipids, followed by esterification of free fatty acids (FFA) using sulfuric acid (H₂SO₄, pro analysis grade) as a catalyst. The process variables investigated include the molar ratio of methanol to oil (1:20 and 1:40), microwave irradiation time (15, 20, 30, and 40 minutes), and H₂SO₄ catalyst concentration (5%, 10%, 15%, and 26% w/w relative to oil). The results indicate that the optimum conditions are achieved at a methanol-to-oil ratio of 1:40, 20 minutes of microwave irradiation, and a catalyst concentration of 10% w/w, producing an FFA content of 0.4076%, density of 0.9030 g/cm³, and viscosity of 22.3905 cSt. With an FFA level below 2%, the esterified nyamplung oil meets the required standard as a biodiesel feedstock. This study demonstrates that microwave-assisted esterification is not only effective in reducing FFA levels but also holds great potential for supporting the development of sustainable, environmentally friendly biodiesel derived from locally available resources.