Magnetic MOF-based nanocomposites for rapid and high-capacity capture of lithium ions from aqueous solutions

Lithium recovery from aqueous resources such as seawater, brines, and industrial effluents has emerged as a sustainable alternative to conventional mining, despite the challenges posed by low concentrations and competing ions. Metal–organic frameworks (MOFs), owing to their exceptionally high surface area, tunable porosity, and versatile chemical functionality, present remarkable potential for highly efficient Li + adsorption, positioning them as advanced candidates for practical deployment in lithium extraction technologies. Herein, a magnetic Fe 3 O 4 @ZIF-67 nanocomposite was successfully synthesized and its potential for rapid lithium ion (Li + ) adsorption was systematically investigated. Comprehensive structural characterizations confirmed a high surface area, mesoporosity, and the coexistence of Co–N and Fe–O functionalities serving as active adsorption sites. Batch experiments, optimized by response surface methodology, demonstrated a maximum capacity of 7.36 mg/g and >92% Li + capture within just 10 min at near-neutral pH. Kinetic modeling revealed heterogeneous chemisorption (Elovich and pseudo-first-order), while isotherm studies fit the Freundlich model, confirming multilayer adsorption on energetically diverse sites. Mechanistic interpretation indicated synergistic electrostatic attraction, surface complexation, and minor precipitation pathways. The composite retained more than 75% of its initial adsorption capacity even after five consecutive regeneration cycles. This highlights both the superior lithium recovery and the stable regenerability of the adsorbent. Our study demonstrates that integrating MOF chemistry with magnetic functionality effectively bridges critical gaps in kinetics, separability, and reusability, advancing MOF-based composites toward scalable lithium recovery technologies. • Magnetic Fe 3 O 4 @ZIF-67 nanocomposite synthesized for lithium-ion adsorption • Active Co–N and Fe–O sites facilitate efficient lithium adsorption. • Effective parameters were systematically optimized via RSM-CCD. • Maximum capacity of 7.36 mg/g achieved within 10 min at optimal conditions. • Mechanism involves electrostatic attraction, complexation, and precipitation.