Preparation of magnetic Fe3O4 composite Cu-MOFs and their removal of perrhenate ions

The removal of toxic pollutants from wastewater, especially radioactive contaminants, has attracted the attention of scientists worldwide. Pertechnetate TcO4-, as an oxyanion with a high oxidation state of technetium, is one of the harmful radionuclides due to its high mobility in the environment. The removal of TcO4- or its nonradioactive substitute, ReO4-, is becoming significant. MOFs represent a class of excellent adsorbents for water remediation due to their large specific surface area, tunable pore structure, phase purity, and thermal stability. A copper-based Metal-Organic Framework (MOF) was synthesized by hydrothermal methods and modified with nano-Fe3O4 particles. Through a series of adsorption experiments, the factors influencing the removal rate of ReO4- were investigated, including pH values, the initial concentration of the adsorbate, and the adsorbent dosages. Under photodegradation conditions, the removal rate of ReO4- reached 85 % over the pristine Cu-MOF adsorbent and increased to 97 % over the modified Cu-MOF@Fe3O4 composite material. Introducing magnetic moieties enabled the composites to recover efficiently with external magnets.