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

Employing metal-organic frameworks (MOFs) for heavy metals removal from water faces ongoing challenges to balance performance with cost. We report the first application of Calgary Framework 20 (CALF-20), a zinc-based MOF, 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 exhibits 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 follow the pseudo-second-order model, while equilibrium data align well with the Langmuir isotherm. CALF-20 demonstrates strong performance under competitive conditions, removing over 99 % of Cu(II) and 80 % of Pb(II). The high adsorption capacity, low synthesis cost, and good regeneration over multiple cycles of CALF-20 for Cu(II) and Pb(II) removal highlight its strong potential for industrial scale water treatment and environmental remediation. • CALF-20 demonstrates high adsorption capacities of 250 mg/g for Cu(II) and 833 mg/g for Pb(II). • Batch and continuous flow tests confirm CALF-20's effectiveness in water remediation. • CALF-20 retains over 90 % adsorption capacity after five regeneration cycles. • CALF-20 achieves 99 % Cu(II) and 82 % Pb(II) selective removal in simulated mining wastewater. • Cost-effective synthesis of CALF-20 supports scalability for industrial applications.