Room-Temperature Synthesis of ZIF-67 for Highly Efficient Tetracycline Hydrochloride Adsorption and Removal Mechanism

The potential ecological risks associated with tetracycline hydrochloride (TC) in water motivate the development of effective, reusable adsorbents. Here, zeolitic imidazolate framework-67 (ZIF-67) is prepared at room temperature and evaluated for TC adsorption under different operating conditions. Kinetic, isotherm, and thermodynamic analyses are combined with physicochemical characterization to examine adsorption behavior and the interactions involved. The synthesized ZIF-67 exhibits a specific surface area of 456 m2·g−1 and achieves 96.07% TC removal at pH 6 with an adsorbent dosage of 0.60 g·L−1 and an initial TC concentration of 100 mg·L−1 after 3 h. The Langmuir fit to the isotherm data yields an estimated maximum adsorption capacity of 365.18 mg·g−1 at 318 K. The calculated thermodynamic parameters indicate that TC adsorption is spontaneous and endothermic under the investigated conditions. ZIF-67 maintains favorable adsorption performance under varying ionic strength and humic acid concentrations, with a removal efficiency of 84.67% in the fifth adsorption cycle. Characterization results suggest contributions from electrostatic interactions and hydrogen bonding, together with possible coordination and π–π interactions, to TC adsorption. These findings demonstrate the potential of room-temperature-synthesized ZIF-67 as a reusable adsorbent for antibiotic-contaminated water treatment.