Heavy metal ion removal of wastewater by zeolite-imidazolate frameworks

With the rapid development of industrialization, removing heavy metal ions of wastewater from the discharge of industrial sewage is a very important topic, because it will severely affect our environment and water ecosystem. In this work, we synthesize two porous adsorbents of ZIF-8 and ZIF-67 and further investigate their performance of removing Pb2+ and Cu2+ from wastewater. Results indicate that saturated adsorption capacities of ZIF-8 and ZIF-67 for Pb2+ reach 1119.80 and 1348.42 mg/g, while they are 454.72 and 617.51 mg/g for Cu2+, respectively, which are greatly higher than almost all other porous materials. If we use the excessive adsorbents to treat wastewater, more than 99.4% Pb2+ and 97.4% Cu2+ can be removed by ZIF-8 and ZIF-67 adsorbents. Moreover, the two adsorbents also show fast adsorption kinetics, and only need several decade minutes to reach adsorption equilibrium. These features indicate that ZIF-8 and ZIF-67 are excellent candidates for removal of heavy metal ions from wastewater.