Hybrid valorization of biodiesel production using sustainable mixed alcohol solvent

The growing global need for energy has resulted in a rise of interest in renewable energy-based fuels such as biodiesel. Palm oil mill effluent, a waste that is produced in large quantities, was used for biodiesel production. 90% of residual palm oil was successfully recovered from the effluent of palm oil mills at extraction conditions of mixing speed of 500 rpm and mixing duration of 25 min. The extracted oil was used to produce biodiesel under the influence of semi-batch heating. Aspen plus simulation model was also developed to compare the performance with the experimental findings. The influence of four process parameters includes reaction temperature of 30–70 °C, time of reaction 1–5 h, solvent to oil mole ratio of 3–15 and catalyst amount of 0.5–2.5%. The optimized experimental and simulated biodiesel yield of 94.73% and 92.83% at the operating conditions of reaction temperature of 60 °C, a reaction time of 4 h, alcohol to oil molar ratio of 12:1 and 2% catalyst concentration. The agreement between predicted and actual biodiesel yield was found to be 98%. The coefficients of estimates of 22.88, 27.29, 32.24 and 22.86 were calculated by the quadratic model for alcohol/oil molar ratio, reaction time, reaction temperature and catalyst loading respectively. The study showed a higher biodiesel yield (94.73%) by using the solution of methanol and ethanol for biodiesel synthesis. Therefore, RPO could possibly result in cheaper biodiesel synthesis and can contribute to make up the energy needs if implemented on an industrial scale.