Metal-organic frameworks: Challenges and opportunities for ion-exchange/sorption applications

Exposure to common ionic pollutants, such as heavy metal ions and toxic anions, is a major concern throughout the world due to their potential impacts on human health and the environment. Recently, metal-organic frameworks (MOFs) with ion-exchange properties have attracted great interest with respect to the capture of diverse hazardous cationic and anionic species. In fact, according to the investigations on these ion exchangers, their sorption capacities are recognized to be considerably superior to conventional materials. This review focused on metal-organic materials as sorbents for ions by surveying MOFs with respect to their exchange/sorption capacities in association with their synthesis and structural characteristics. We also described the recent development in MOF composites and their practical applications toward wastewater treatment. The sorption characteristics were also evaluated among the reported MOFs and then between MOFs and other sorbents. Finally, we described the future prospects for the research and development in materials for ion-exchange based on MOF technology.