Kinetic studies on the sequestration of Pb2+ and Ni2+ ions in aqueous solutions using manganese nanoparticles anchored in ixora coccinea

Abstract

This study reports the green synthesis, characterization, and adsorption performance of manganese nanoparticles produced using plant extract. FTIR analysis confirmed functional group involvement through peak reductions and shifts, while XRD revealed a major diffraction peak at 28.45° with a d-spacing of 3.13 Å, indicating crystalline nanoparticle formation. The nanoparticles exhibited very high adsorption capacities for Ni²⁺ and Pb²⁺, reaching 99.32 mg/g and 99.63 mg/g respectively within 60 minutes. Kinetic evaluation showed that pseudo-first-order and pseudo-second-order models did not adequately describe the adsorption behaviour, whereas the Elovich and intraparticle diffusion models provided better fits, indicating heterogeneous surface interactions and mixed diffusion mechanisms. The results demonstrate the potential of these nanoparticles for efficient heavy-metal removal from aqueous systems