Kinetics, thermodynamic studies, and parametric effects of supercritical CO₂ extraction of banana peel wastes

The quest for the recovery of bioactive compounds from food waste is foreseeable with multi-benefits in line with the essential thoughts of the trio sustainability indicators which are to stimulate waste management, reduce the cost of production, bypass resource competition for using edible feedstock and push for greener and sustainable recovery of bioactive compounds for use in pharmaceutical and other industrial applications. In this work, banana peel waste was used as a reusable bioresource to recover extract using supercritical carbon dioxide (Sc-CO₂) extraction. High-Performance Liquid Chromatography (HPLC) was explored to quantitatively isolate three bioactive compounds namely quercetin, beta-carotene, and gallic acid from the extract. Qualitative characterization using Scanning Electron Microscope (SEM) was carried out to examine the surface morphology of the pre-and post-extracted milled banana peel sample. The mass transfer reaction involved in the Sc-CO₂ extraction was studied using Elovich's, Hyperbolic, and Pseudo second-order kinetic models and were suitably fitted to the experimental data with an average correlation coefficient (R²) value greater than 0.98. Among the kinetic models, the experimental data were best fitted to the Hyperbolic model. Lastly, on the thermodynamic parameters, Gibbs’ free energy, (ΔG), enthalpychange(ΔH), and entropy change (ΔS) calculated at the optimum temperature of the extraction process were -13.29 kJ/mol, 116.99 kJ/mol, and 0.299 Jmol^-1K^-1, respectively, indicated that the extraction process was spontaneous and endothermically irreversible reactions.