Characterization, bioactivity evaluation, thermo-kinetic studies of mango (Mangifera indica L.) peel extract, and its applicability in oxidative stabilization of biodiesel

Supercritical fluid extraction (SFE) of mango peel (MP) waste, characterization, kinetics, and thermodynamic studies was carried out in this work. Experimental conditions employed for the extraction process were a CO2 flow rate of 9.8 g/min, a fixed pressure of 25 MPa, and different temperatures of 40-80 celcius over varied extraction times of 30-150 min. High-performance liquid chromatography (HPLC) was used to isolate three (3) target bioactive compounds namely, quercetin, beta-carotene, and gallic acid, whose quantities were estimated as 1.2983, 3.6987, and 0.0254 mg/g respectively. The applicability of using Elovich's, Hyperbolic, and Pseudo second-order models to study the extraction kinetics of MP liquid extracts derived from SFE was investigated and validated using calculated error functions. The result shows that the experimental data were best fitted by Hyperbolic, followed by Pseudo second-order and Elovich's model respectively. Thermodynamics parameters gave positive values of entropy change (delta S) = 0.144 Jmol(-1)K(-1), enthalpy change (delta H) = 59.78 KJ/mol, and a negative Gibbs' free energy, (delta G) = -8.88 KJ/mol, indicating an irreversible and endothermically spontaneous process respectively. Finally, the work also unveiled the potency of MP liquid extracts as a low-cost and sustainable source of antioxidants for improving biodiesel's oxidative stability.

Automated summary

This study conducted the characterization, kinetics, and thermodynamic studies of mango peel (MP) waste using supercritical fluid extraction (SFE). The experimental conditions included a CO2 flow rate of 9.8 g/min, a fixed pressure of 25 MPa, and temperatures ranging from 40-80 degrees Celsius for extraction times of 30-150 minutes. High-performance liquid chromatography (HPLC) was used to isolate three target bioactive compounds: quercetin, beta-carotene, and gallic acid, with estimated quantities of 1.2983, 3.6987, and 0.0254 mg/g respectively. The kinetics of MP liquid extracts derived from SFE were best described by the Hyperbolic model, followed by the Pseudo second-order and Elovich's models. The thermodynamic parameters indicated an irreversible and endothermically spontaneous process, with positive entropy change (ΔS) of 0.144 Jmol(-1)K(-1), positive enthalpy change (ΔH) of 59.78 KJ/mol, and negative Gibbs' free energy (ΔG) of -8.88 KJ/mol. The study also highlighted the potential of MP liquid extracts as a low-cost and sustainable source of antioxidants for improving biodiesel's oxidative stability.