Al(III)-based MOF for tetracycline removal from water: Adsorption performance and mechanism

Abstract

The high concentration of pharmaceuticals in water systems can harm the ecosystem and human health. Tetracycline (TC) is a human and veterinary antibiotic widely used for bacterial infections. The excessive use of TC has resulted in a risk to health and the environment since TC has been found in various water ecosystems. Then, this study focuses on effectively removing tetracycline from water solutions using an Al(III)-based MOF CYCU-3. The material showed high adsorption in the pH range of 4–9 with an equilibrium time of 120 min and outstanding cyclability. The maximum adsorption capacity was 428.1 mg g−1. The experimental data were fitted into Pseudo-Second Order (PSO) and Temkin models, suggesting physicochemical interactions. The thermodynamic study proved the exothermic nature of the process. The adsorption mechanism was proposed based on the experimental analysis, Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and theoretical calculations. It was proposed that cation-π, π-π interactions, and hydrogen bonding played the main role in adsorption. CYCU-3 displays higher adsorption capacity compared with some representative porous materials. Therefore, CYCU-3 can be considered a suitable adsorbent for the treatment of water contaminated with pharmaceuticals.