Oxytetracycline Removal by Ti₃AlC₂ (MAX Phase): Effects of pH, Temperature, Dosage, and Initial Concentration with Kinetic and 60-min Isotherm-Like Analyses

This study evaluates the removal of oxytetracycline (OTC) from aqueous solutions using Ti₃AlC₂ (MAX phase) based on experimental data. The adsorbent was characterized by XRD, SEM, TEM, EDX, and XPS analyses. Batch adsorption experiments were conducted to investigate the effects of pH (2–11), temperature (25–60 °C), adsorbent dosage (0.2–0.5 g per 50 mL), and initial OTC concentration (10–50 mg L⁻¹). The removal efficiency increased with increasing pH and temperature, reaching its highest performance at pH 11 and 60 °C. An adsorbent dosage of 0.2–0.3 g achieved approximately 80–83% OTC removal after 60 min at an initial concentration of 30 mg L⁻¹. While the removal efficiency remained close to 80% with increasing initial concentration, the adsorption capacity increased from 1.93 to 10.31 mg g⁻¹. Kinetic analysis showed that the pseudo-second-order (PSO) model provided a better fit than the pseudo-first-order (PFO) model (R² = 0.915). An isotherm-like evaluation indicated that the Freundlich model showed a slightly better fit than the Langmuir model. Overall, the results demonstrate that alkaline pH and elevated temperature favor OTC removal and that Ti₃AlC₂ MAX phase can achieve high removal efficiency even at low adsorbent dosages, providing a strong basis for process optimization.