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 TcO 4 − , 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 TcO 4 − or its non-radioactive substitute, ReO 4 − , 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-Fe 3 O 4 particles. Through a series of adsorption experiments, the factors influencing the removal rate of ReO 4 − were investigated, including pH values, the initial concentration of the adsorbate, and the adsorbent dosages. Under photodegradation conditions, the removal rate of ReO 4 − reached 85 % over the pristine Cu-MOF adsorbent and increased to 97 % over the modified Cu-MOF@Fe 3 O 4 composite material. Introducing magnetic moieties enabled the composites to recover efficiently with external magnets. A cyclic binuclear Cu-MOF was synthesized using the solvothermal method, and followed by nano-Fe 3 O 4 composition. The introduction of nano-Fe 3 O 4 increased the specific surface area of Cu-MOF and facilitated the recycling of materials. The removal efficiency of the composite material on ReO 4 − was significantly improved. •A novel Cu-MOF with a cyclic binuclear structure was synthesized to remove perrhenate. •The magnetic Fe 3 O 4 endorses the efficient separation of the composite Cu-MOF@Fe 3 O 4 . •The Cu-MOF@Fe 3 O 4 composite performs an enhanced removal rate of ReO 4 − than that of pristine Cu-MOF.