Efficient Removal of Pb(II) and Cd(II) Using NH₂-Functionalized Zr-MOFs via Rapid Microwave-Promoted Synthesis

Heavy metal ions of Pb(II) and Cd(II) have become the global health and environmental concerns. NH2-functionalized Zr-MOFs were prepared via a rapid microwave-promoted synthesis and first used in the adsorptive removal of both Pb(II) and Cd(II). The nanosized (<100 nm) Zr-MOFs had an XRD pattern of UiO-66-NH2. Effects of adsorption time, temperature, pH, and initial ions concentration were studied on the adsorption of Pb(II) and Cd(II) onto the Zr-MOFs. The absorption results showed that the removal of Pb(II) was 99.95% after 120 min at temperature of 30 °C and pH of 6 with an initial concentration of 10 mg·L–1. And the adsorption capacity of Cd(II) achieved 177.35 mg·g–1 at an initial concentration of 40 mg·L–1. The adsorption fit the pseudo second-order kinetic model well and the mechanism was confirmed mainly as a coordination interaction between the amino group (−NH2) and Pb(II) or Cd(II). The NH2-functionalized Zr-MOFs have been proven to show good performance in the removal of heavy metal ions as an efficient adsorbent.