MOFs are porous materials that self-assemble and have a variety of topologies, large surface areas, and customizable pore structures . A subclass of microporous MOFs known as zeolitic imidazolate frameworks-8 (ZIF-8) is made up of 2-methylimidazole (Hmim) as an organic linker and zinc metal ions as coordination centers . Microporous ZIF-8 has attracted a lot of research interest for heavy metal adsorption because of its desirable properties such as high surface area, high chemical and thermal stability, adjustable pore structure, and ease of synthesis . However, the limited applicability of microporous ZIF-8 is due to its small pore size ) and lack of an acido-basic site . This challenge can be solved using hierarchical porous ZIF crystals .