High Performance of Al-MCM-41 in Tetracycline Adsorption Using a Fixed-Bed Column

This study investigates the adsorption efficacy of aluminum-modified mesoporous silica (Al-MCM-41, Si/Al = 16.1) for the removal of tetracycline (TC) from aqueous solutions, employing both batch and fixed-bed column systems in the quest for sustainable solutions to eliminate emerging contaminants. The synthesized material exhibited a highly ordered hexagonal structure and high surface area (∼850 m² g^-1), confirmed by X-ray diffraction, nitrogen physisorption, FTIR, and transmission electron microscopy analyses. Batch adsorption kinetics followed a pseudo-second-order model, indicating surface-controlled uptake, while isotherm data fit both Langmuir and Freundlich models, with a maximum adsorption capacity of 82.74 mg g^-1. Thermodynamic analysis revealed a spontaneous and exothermic process (Δ<i>H</i>° = -25.8 kJ mol^-1), suggesting combined physisorption and weak chemisorption. In fixed-bed column experiments, the Yan model provided the best fit to breakthrough curves, achieving an adsorption capacity of 19.1 mg g^-1 at an influent concentration of 15 mg L^-1. These results demonstrate the good efficiency and practical applicability of Al-MCM-41 in continuous-flow systems for removing emerging contaminants such as TC, supporting the development of sustainable water treatment technologies.