A scalable and cost-effective zinc-based MOF for efficient Cu(II) and Pb(II) removal from aqueous solutions

The development of metal-organic frameworks (MOFs) for heavy metals removal from water faces ongoing challenge related to balancing performance with cost-effective synthesis. In this work, we report the first application of Calgary Framework 20 (CALF-20), a zinc-based MOF synthesized via a low-cost method, for the efficient adsorption of Cu(II) and Pb(II) ions from aqueous solutions. Synthesized at room temperature using commercially available, inexpensive reagents and green solvents, CALF-20 represents a highly economical alternative to many conventional MOFs. It exhibited excellent adsorption efficiency, achieving uptake capacities of 250 mg/g for Cu(II) and 833 mg/g for Pb(II) at the optimum pH of 5.3, outperforming many MOFs reported to date. Adsorption kinetics followed the pseudo-second-order model, while equilibrium data aligned well with the Langmuir isotherm. CALF-20 was demonstrated strong performance under competitive ion conditions, removing over 99% of Cu(II) and 80% of Pb(II). The material’s high adsorption capacity, low synthesis cost, chemical robustness, and reusability across multiple cycles underscore its potential for industrial scale water treatment and environmental remediation.