Comparative Batch Adsorption Study of Crude Oil Removal from Simulated Oil Spill Using Quail Egg Shell and Snail Shell Biosorbents

Abstract

Oil spill incidents in petroleum-producing regions present major ecological threats. Although various commercial adsorbents have demonstrated effective pollutant removal capabilities, their high cost, toxicity, and non-biodegradable nature restrict their large-scale application. This study explores the use of quail eggshells (QES) and snail shells (SS) as eco-friendly and low-cost alternatives for mitigating oil pollution. A total of 300 g of each shell type was collected, crushed, and oven-dried at 120 °C for 48 hours. The dried samples were then pulverized and sieved into two particle sizes: 106 µm and 425 µm. To maximize surface area and potential adsorption capacity, the finer 106 µm fraction was selected for all subsequent analyses. Characterization via Fourier Transform Infrared (FTIR) spectroscopy identified key functional groups: metal carbonyl peaks appeared at 1789.17 cm⁻¹ for QES and 1642.5 cm⁻¹ for SS, indicating the presence of active adsorption sites. Batch adsorption experiments were carried out to investigate the impact of several operational parameters namely, temperature, agitation speed, adsorbent dose, oil concentration, and contact time on crude oil removal efficiency.  To describe the adsorption equilibrium, four classical isotherm models; Langmuir, Freundlich, Dubinin–Radushkevich, and Temkin were applied. Additionally, adsorption kinetics were evaluated using pseudo-first-order and pseudo-second-order models. The kinetic results revealed that the pseudo-second-order model provided the best fit to the experimental data, suggesting that the dominant mechanism was chemisorption involving electron exchange or sharing between adsorbent and adsorbate. Oil removal efficiencies ranged between 25.0% and 77.5% for QES, and between 40.0% and 95.0% for SS, with maximum performance observed at an adsorbent dosage of 5 g. Across all tested conditions, SS consistently outperformed QES, demonstrating up to 35% higher efficiency. In general, the Langmuir isotherm provided the best fit for SS data, reflecting monolayer adsorption on a homogeneous surface, while the Temkin model was more suitable for QES, indicating a heterogeneous surface with variable adsorption energies. Both QES and SS exhibited significant potential as efficient, sustainable, and cost-effective alternatives to conventional synthetic adsorbents in oil spill remediation applications.