Supercritical CO2 separation of lipids from chicken by-product waste for biodiesel production: optimization, kinetics, and thermodynamics modeling

There is an increasing concern on the safe disposal and sustainable utilization of chicken by-product waste to minimize adverse environmental impacts. Besides, the rising dependency on petro-diesel in automobiles and industrial sectors leads to the search for alternative energy sources to replace or supplement rapidly depleting petro-diesel. The present study employed supercritical CO2 (scCO(2)) to separate lipids from chicken by-product waste for biodiesel production. The influence of the scCO(2) extraction on the separation of lipids was conducted with varying pressure (8-40 MPa), temperature (30-80 degrees C), and treatment time (15-90 min). The experimental conditions of scCO(2) separation were optimized based on the maximum separation of lipids from chicken by-product waste using response surface methodology (RSM). Results show that the scCO(2) pressure, temperature, and separation time significantly influence the lipid separation from chicken by-product waste. The maximum lipid separation obtained was 49.61% at the optimized experimental conditions of scCO(2) separation: pressure 20 MPa, temperature 60 degrees C, and separation time 60 min. Moreover, a second-order kinetics model and Eyring theory were utilized to determine the kinetics and thermodynamics behavior of scCO(2) separation of lipids from chicken by-product waste. Approximately 79% of biodiesel was synthesized from the scCO(2) separated lipids from chicken by-product waste with a conventional catalytic transesterification process using NaOH as a catalyst. Physicochemical properties and fatty acid composition analyses of lipids and biodiesel reveal that the chicken by-product waste lipids could be utilized as a potential feedstock for biodiesel production.