Extracted fat from lamb meat by supercritical CO₂ as feedstock for biodiesel production

The feasibility of enzymatic production of biodiesel from waste animal fats using supercritical fluid technology for the extraction and reaction has been investigated. The operating conditions that resulted in the optimum extraction and biodiesel production yields were identified. The effects of extraction temperature, pressure and supercritical CO₂ (SC-CO₂) flow rate were investigated in the ranges of 35-55°C, 300-500bar and of 3-5mlmin^-1, respectively, and optimized using response surface methodology (RSM). In addition, the effects of reaction temperature, methanol:fat molar ratio and enzyme loading on biodiesel production yield were investigated in the ranges of 35-60°C, 3:1-6:1 and 10-50%, respectively. The optimum conditions for supercritical fluid extraction (SFE) were determined to be 45°C, 500bar and 3mlmin^-1; at which, 87.4% of total fat content was extracted from freeze dried meat. The statistical analysis however, showed that pressure has negligible effect on the extraction yield, which is extremely important, as it allows saving energy by using lower pressure. On the other hand, biodiesel yield of 40% was obtained using extracted fat as feedstock in SC-CO₂ medium at 50°C, 200bar, 4:1 methanol:fat molar ratio and 30% loading of lipase enzyme, after 24h of reaction. The experimental results were used to fit a suitable reaction kinetic model using non-linear regression analysis to estimate the model parameters.