Fish waste oil extraction using supercritical CO2 extraction for biodiesel production: Mathematical, and kinetic modeling

The safe disposal of organic waste is a big environmental issue in landfills because of its huge generation volume. The main goal of this research is to determine the effect of supercritical carbon dioxide (scCO2) on the extraction of fish waste oil from discarded fish waste for producing biodiesel. Oil from fish waste was extracted using supercritical fluid extraction process using CO2 as a solvent. The supercritical carbon dioxide (scCO2) extraction was carried out with varying extraction pressure (10–40 MPa), temperature (32–80 °C), and treatment time (15–120 min). The maximum fish waste oil yield obtained was about 77.2 % at a temperature of 80 °C, a pressure of 30 MPa and a time of 60 min. The kinetics and thermodynamic behavior of the scCO2 extraction were calculated using Arrhenius law and Eyring theory, respectively. The estimated activation energy Ea value was 24.45 kJ/mol for the scCO2 extraction of discarded fish waste oil. Approximately 87 % of biodiesel was produced from scCO2 extracted oil via alkaline transesterification process with reaction temperature of 65 °C, NaOH loaded 1 wt%, fish oil to methanol molar ratio of 1:9, and treatment time of 3 h. The characterization of the produced biodiesel showed that its properties complied with the biodiesel standards (EN 14214 & ASTM D6751). The finding of this research revealed that the fish waste could be consumed as a biofuel feedstock.