Zinc oxide-nanoparticle impregnated poultry droppings activated carbon for model oil desulfurization: Experimental investigation and regression modelling with uncertainty quantification

This study presents a novel, eco-friendly approach for adsorptive desulfurization, utilizing Poultry Droppings (PD) and Garlic Peel (GP) wastes to develop a high-performance green adsorbent for the removal of Dibenzothiopene (DBT) from Model Oil (MO). PD was thermally and chemically modified to PD-Activated Carbon (PDAC) and PDAC impregnated with Zinc Oxide Nanoparticles (PDAC-ZnO-NPs). The produced adsorbents (PDAC and PDAC-ZnO-NPs) were appropriately characterized. Batch adsorption experiment was designed by Definitive Screening Design (DSD) for parameters: adsorption temperature (25 – 50°C), contact time (10 – 60 min), agitation rate (50 – 250 rpm), and adsorbent dosage (50 – 250 mg). ZnO nanoparticle impregnation increased the surface area from 965 m²/g to 981 m²/g and enhanced the availability of oxygen-containing functional groups, thereby improving DBT affinity. The BET surface area increased from 965 m²/g to 981 m²/g after ZnO-NP impregnation, indicating enhanced adsorption capacity. The equilibrium data for DBT removal were fitted to isotherm, kinetic, and thermodynamic models, with model constants evaluated. The desulfurization process achieved an optimum DBT percentage removal (%DBTR) of 85.47 % with PDAC and 95.12 % with PDAC-ZnO-NPs. The desulfurization equilibrium data fitted the Freundlich isotherm, the Pseudo-Second-Order (PSO) kinetic model and, thermodynamic analysis indicated that DBT removal process was spontaneous and endothermic, with entropy (ΔS) and enthalpy (ΔH) changes of 140.12 J/mol·K and 40.25 kJ/mol for PDAC, and 110.49 J/mol·K and 30.01 kJ/mol for PDAC-ZnO-NPs respectively. The %DBTR decreased by 6.1 % for PDAC-ZnO-NPs after five regeneration cycles, demonstrating its reusability. This study demonstrates the potential of sustainable bio-based adsorbents for efficient adsorptive desulfurization, paving the way for cleaner fuel production and enhanced environmental sustainability.