Effect of metal atom in zeolitic imidazolate frameworks (ZIF-8 & 67) for removal of Pb²⁺ & Hg²⁺ from water

Heavy metals especially lead (Pb) and mercury (Hg) are recognized as most emerging pollutants in underground water and are major threat to public health around the world. Major challenge to mitigate water pollution is construction of effective materials containing a host of deceivingly accessible high-density and high-level efficiency. Herein, we have synthesized two metal-organic frameworks (MOFs) with efficient porosity showing the right combination of structures. Representatively, ZIF-8 and ZIF-67 were designed by reacting Zn, Co salts with 2-methyl imidazole showing superior efficacy in removing Pb and Hg (1978.63&1436.11 mg/g respectively) from water. These adsorbents displayed high distribution values permitting them to quickly reduce concentration level of Pb²⁺, Hg²⁺ below permissible limit (Pb = 0-15 μg/L, Hg = 1-10 μg/L). EDX, FTIR analysis revealed that Pb²⁺, Hg²⁺ bound through weak interactions. Results presented here have shown extraordinary potential with high environmental remediation performance having 99.5% and 98.1% removal efficiency for lead & mercury respectively. Results revealed that adsorbents have same organic linker that identifies same morphology required for adsorption. The difference in adsorption capacity and porosity (ZIF-8 = 937&1370 m²/g, ZIF-67 = 1289&1889 m²/g) are deliberately caused due to presence of metal atoms having different electronic distribution, as cobalt in ZIF-67 and in case of ZIF-8 zinc metal.