Functionalized metal–organic frameworks for heavy metal ion removal from water

Water purification is becoming increasingly important due to the scarcity and industrial contamination of water. Although traditional adsorbents such as activated carbon and zeolites can remove heavy metal ions from water, they have slow kinetics and low uptake. To address these problems, metal-organic framework (MOF) adsorbents have been developed, which are characterized by facile synthesis, high porosity, designability, and stability. Water-stable MOFs, such as MIL-101, UiO-66, NU-1000, and MOF-808, have attracted considerable research interest. Thus, in this review, we summarize the developments of these MOFs and highlight their adsorption performance characteristics. Moreover, we discuss functionalization methods that are typically used to improve these MOFs' adsorption performance. This minireview is timely and will help readers understand the design principles and working phenomena of next-generation MOF-based adsorbents.