Sequestration of Ni (II), Pb (II), and Zn (II) utilizing biogenic synthesized Fe₃O₄/CLPC NCs and modified...

The present study reports low-cost novel biogenic magnetite Citrus limetta peels carbon (Fe₃O₄/CLPC) nanocomposites and modified Fe₃O₄/CLPC@CS nanocomposites cross-linked with glutaraldehyde and subsequently employed in batch mode sequestration of heavy metals ions. Diverse techniques fully characterized them, and the influence of operating variables on adsorption reactions from aqueous solutions was investigated. The Brunauer, Emmett, and Teller (BET) surface areas of synthesized Fe₃O₄/CLPC and Fe₃O₄/CLPC@CS NCs were 53.91 and 32.16 m²/g, while the mesoporous diameters were 7.69 and 7.57 nm, respectively. The Langmuir isotherm and Pseudo second order kinetic were well-fitting and capable of explaining the adsorption reaction. The Langmuir-based monolayer adsorption (q_max) for Fe₃O₄/CLPC@CS NCs was 82.65, 95.24, and 64.10 mg/g, higher than Fe₃O₄/CLPC NCs, which were 70.92, 84.75, and 59.17 mg/g for Ni (II), Pb (II), and Zn (II), respectively. Each metal's pseudo second order correlation coefficient (R² ≥ 0.99) reveals that nanocomposites surface binding functional groups controlled the adsorption rate via chemisorption. Further, thermodynamic results confirm that each studied metal ions' adsorption was spontaneous, endothermic, and characterized by an increase in randomness. In addition to magnetic separability, three ad-desorption cycles yielded exceptional adsorption efficacy and > 93% regenerability. The present study also reveals the effective utilization of Fe₃O₄/CLPC and Fe₃O₄/CLPC@CS NCs as cost-effective magnetic separable green adsorbents for heavy metals sequestration from electroplating wastewater.