Study of the Kinetics of Cu(II) and Pb(II) Sorption on Magnetically Functionalized MXene Composites

We report a comprehensive investigation of Cu(II) and Pb(II) ion sorption kinetics on magnetically functionalized Ti₃C₂T_x MXene composites. The composite material was synthesized by functionalizing multilayer MXenes with iron oxide nanoparticles through a co-precipitation method, resulting in a magnetic sorbent with a saturation magnetization of 32 ± 3 A m²/kg. The experimental data were analyzed using pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. The sorption process for both metal ions followed pseudo-second-order kinetics (R² > 0.99), with activation energies of –61.5 and ‒24.8 kJ/mol for Cu(II) and Pb(II), respectively. The analysis revealed that Cu(II) sorption involves both chemical interactions with functional groups and diffusion processes, while Pb(II) sorption is primarily diffusion-controlled. External diffusion rates were found to be an order of magnitude higher than internal diffusion rates for both metal ions, suggesting that the 2D structure of MXenes may influence the intraparticle diffusion of heavy metals. The magnetic functionalization enables efficient separation of the sorbent after treatment, making this composite material promising for heavy metal removal applications in water treatment processes.