Synthesis of functionalized magnetic bimetallic-based organic frameworks for efficient removal of Pb (II)

This investigation addressed the challenge of lead-containing wastewater treatment. We successfully synthesized a novel bimetallic magnetic adsorbent, MOF@Fe₃O₄-PAA, for Pb(II) removal by incorporating Ti ions via hydrothermal/chemical modification. Combined SEM, XRD, BET, FTIR, and XPS characterization elucidated its structure-property relationships. Results demonstrated optimal adsorption at pH 5.0 with a maximum capacity of 295.8 mg/g. Kinetics followed the pseudo-second-order model (R²=0.999), indicating chemisorption dominance. Isotherm analysis favored the Temkin equation (R²=0.979), suggesting combined physicochemical interactions. Thermodynamics revealed spontaneous exothermic adsorption (ΔG < 0, ΔH < 0) with enhanced efficacy at low temperatures. Selectivity tests showed significantly higher affinity for Pb(II) over competing ions (e.g., Cu²⁺, Zn²⁺). Amino (-NH₂) and sulfhydryl (-SH) functional groups enabled Pb(II) binding via coordination, yielding high adsorption capacity, rapid equilibrium attainment, and facile magnetic recovery. This work provides an innovative strategy for efficient wastewater Pb(II) removal.