Ternary polymeric beads of chitosan-based polyaniline doped iron oxide used for removal of cadmium and lead ions from water: Kinetic, isotherm and mechanism studies

In this study, the binary polymeric magnetic beads were synthesized successfully by one-pot polymerization of polyaniline (PA) doped magnetic iron oxide nanoparticles (MNPs) followed by chitosan (CTS) cross-linkage. The newly fabricated ternary magnetic beads (CTS@MPA) were applied to enhance the removal of Pb(II) and Cd(II) ions from the aqueous media. The prepared nanocomposite was characterized using Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometry (VSM). Adsorption experiments were carried out under optimum conditions. To evaluate the experimental data, the isotherm and kinetic models were conducted. The behavior of adsorption was assessed, and the coefficient of determination values demonstrated that the adsorption process best fitted the Freundlich model due to high values of R2 (0.957 & 0.981). The maximum adsorption capacity was obtained at 150.82 mg.g-1 and 169.21 mg.g-1 for Pb(II) and Cd(II) ions, respectively. Kinetic studies showed that adsorption follows a pseudo-second-order model (R2 = 0.952 & 0.985). Weber-Morris claims that intraparticle diffusion plays a significant role in the adsorption kinetics. Finally, the thermodynamic study is demonstrated, and the adsorption is endothermic, and the mechanism follows a physisorption pattern.