Room-temperature synthesis of bimetallic ZnCu-MOF-74 as an adsorbent for tetracycline removal from an aqueous solution

Abstract

The novel bimetallic MOF, ZnCu-MOF-74, has been evaluated for the remediation of tetracycline-contaminated water. ZnCu-MOF-74 was obtained at room temperature, avoiding high pressure and temperature. ZnCu-MOF-74 exhibited chemical stability in the 4–8 pH range. The adsorption result analysis was described using the Elovich kinetic model and the Langmuir adsorption isotherm, suggesting a physicochemical process. The maximum adsorption capacity was estimated at 775.66 mg g⁻¹. The pH of the solution and the presence of ions such as NO₃⁻, SO₄²⁻, Na⁺, Mg²⁺, Cl⁻, and Ca²⁺ had no influence on the removal of tetracycline. In addition, π-interactions and metal complexation were proposed as possible adsorption mechanisms through FT-IR and XPS. ZnCu-MOF-74 showed outstanding cyclability performance, preserving its adsorption capacity after 4 adsorption–desorption cycles, besides exhibiting chemical stability, proving the benefits of applying ZnCu-MOF-74 in the water treatment process.