Enhanced Degradation of Oxytetracycline Hydrochloride: A Comparative Study of Adsorption and Catalytic Wet Air Oxidation Using Cuttlefish Bone/CuFe2O4 Ferrite Composites

The direct and sequential application of adsorption and catalytic wet air oxidation (CWAO) methods was evaluated for the removal of the veterinary antibiotic oxytetracycline hydrochloride (OTC-HCl) from wastewater. Cuttlefish bone (CFB), a natural marine material, was employed as both an adsorbent and a catalyst support to synthesize the composite CuFe₂O₄/CFB material. The optimal conditions for OTC-HCl adsorption were found to be 0.09 g/L CFB, pH 7.6, and 282 rpm, resulting in a 24% removal efficiency. The Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich isotherm models were evaluated, with the Temkin isotherm identified as the most suitable. The adsorption kinetics followed a second-order kinetic model. The Weber–Morris intraparticle diffusion model suggested that both liquid film and intraparticle diffusion processes govern the adsorption kinetics. In the catalytic wet air oxidation process, a 75% removal efficiency was achieved at 0.5 g/L CuFe₂O₄/CFB, pH 4, and 100 °C. The most suitable kinetic model for describing the CWAO of OTC-HCl was found to be a two-step first-order reaction rate model. In the hybrid treatment process, CWAO was applied following adsorption, and toxicity tests indicated that no toxic by-products were generated during the sequential treatment.