International Journal of Science, Engineering and TechnologyAuthors: Dr. Malachy. O. Ugwuoke, Dr.Okoye Japheth. O, Dr. Agu Anthony
Abstract: This study investigates the thermodynamics and kinetics of crude oil bioremediation in aqueous systems using soursop peel as a natural biocarrier and Aspergillus niger as the degrading microorganism. Artificially contaminated water was treated over a 35-day period, and key parameters including total petroleum hydrocarbons (TPH), microbial count, and pH were monitored. Kinetic analysis revealed that the biodegradation process followed both first-order and pseudo first-order models. For the first-order model, a strong linear relationship was observed (R² ≈ 0.96) with a decay constant (k ≈ 0.006 day⁻¹), indicating that degradation rate depended on residual hydrocarbon concentration. Similarly, the pseudo first-order model showed excellent agreement (R² ≈ 0.98) with a decay constant (k ≈ 0.007 day⁻¹), confirming the influence of microbial activity and surface interactions. Thermodynamic evaluation using the Van’t Hoff plot (ln K vs 1/T) also exhibited good linearity (R² ≈ 0.96), validating the applicability of thermodynamic principles. The enthalpy change (∆H ≈ +28.5 kJ/mol) indicated that the process is endothermic, while the positive entropy change (∆S ≈ +0.095 kJ/mol·K) suggested increased randomness and enhanced microbial-substrate interaction. The Gibbs free energy change (∆G ranged from −12.6 to −9.8 kJ/mol) confirmed that the biodegradation process is spontaneous and thermodynamically feasible. Finally, the results demonstrate that soursop peel is an effective, low-cost biocarrier that significantly enhances microbial degradation of crude oil. The combined kinetic and thermodynamic findings confirm that the process is efficient, feasible, and temperature-dependent, making it suitable for sustainable remediation of hydrocarbon-contaminated water systems.
DOI: http://doi.org/10.5281/zenodo.20376931
