A comprehensive review on the adsorption of heavy metals by zeolite imidazole framework (ZIF-8) based nanocomposite in water

Zeolite imidazolium skeleton-8 (ZIF-8) is a metal–organic framework (MOF) synthetic material with huge specific surface area, diverse structure, adjustable pore size, and easily designed and controlled pore surface characteristics, showing good potential for heavy metal (HMs) removal applications. This makes it a highly sought-after material in wastewater treatment. However, other ZIFs particles tend to clump together in aqueous solutions, resulting in reduced adsorption capacity. In addition, it is difficult to separate them from the water after the removal of contaminants, having poor recoverability. However, ZIF-8 based composite material (ZBC) solved the above problems and was successfully applied to HM in wastewater treatment. This review summarizes the synthetic design approach of ZBC, outlines the influencing factors, theoretical calculations, and characterization of HM removal behavior based on ZBC, as well as the possible interaction pathways. An attempt was made to lay down mechanistic insights for the application of ZBC in practical wastewater treatment and to provide new ideas for the construction of efficient ZBC adsorbents. In addition, the performance of ZIFs and other series of Metal-organic frameworks materials for HM ion removal is objectively compared. Finally, the problems and directions of ZBC in future environmental pollution treatment are discussed to guide the development and practical application of this material.