Adsorption behavior and adsorption mechanism of Cu(II) ions on amino-functionalized magnetic nanoparticles

Amino-functionalized magnetic nanoparticle (NH2-MNP) were prepared by a sol-gel approach. The adsorption behavior of Cu(II) ions on NH2-MNP was discussed systematically by batch experiments. The effects of initial Cu(II) ions concentration, time, pH and temperature were investigated. In kinetic studies, the pseudo-second-order model was successfully employed, and the pseudo-first-order model substantiated that Cu(II) adsorption on NH2-MNP was a diffusion-based process. Langmuir model and Dubinin-Radushkevich model (R2>0.99) were more corresponded with the adsorption isotherm data of Cu(II) ions than Freundlich model. The adsorption capacity was increased with the increment of temperature and pH. NH2-MNP remains excellent Cu(II) recoveries after reusing five adsorption and desorption cycles, making NH2-MNP a promising candidate for repetitively removing heavy metal ions from environmental water samples. According to the results obtained from adsorption activation energy and thermodynamic studies, it can be inferred that the main adsorption mechanism between absorbent and Cu(II) ions is ion exchange-surface complexation.