Recent Advances in Adsorptive Removal of Cr(VI) Ions by Metal-Organic Frameworks

The pollution of heavy metal ions has long been a big concern to the society. The development and utilization of porous materials for the adsorptive removal of heavy metal ions in water represents one of the hottest research subjects in related areas, such as materials science and environmental science. Due to their structural variety, large specific surface area, adjustable pore size, and tailorable pore surface characteristics, metal-organic frameworks (MOFs) show great potential in many applications, such as gas separation, catalysis, and sensing. In the past few years, many major breakthroughs have been made in the construction of highly stable MOFs. A lot of research works have been explored for the applications of MOFs in water systems, including the adsorptive removal of heavy metal ions in water. Cr(VI) ions are a kind of wide-distributed heavy metal ions with high toxicity, existing in water in various forms under different conditions. The study on the removal of Cr(VI) ions from water is of significance academically and practically. Herein, the published research works about adsorptive removal of Cr(VI) ions with MOFs or MOF-based materials are reviewed. These materials are classified into four classes: (1) highly stable zirconium-based MOF, (2) cationic MOF, (3) post-modified MOF, and (4) MOF-based composite materials. The adsorption mechanism, adsorption capacity, and regenerability of these materials for Cr(VI) ions are also discussed. The existing problems and the trend of future works for the practical application of MOFs in the removal of heavy metal ions are analyzed at last.

Automated summary

The pollution of heavy metal ions is a major concern, and the utilization of metal-organic frameworks (MOFs) for the removal of heavy metal ions in water is a hot research topic. Research on the adsorptive removal of Cr(VI) ions is significant both academically and practically.