The kinetic and thermodynamic adsorption of Eu(III) on synthetic maghemite

In this study, maghemite (γ-Fe2O3) nanoparticles were synthesized by calcining limonite under H2 atmosphere. The adsorption of Eu(III) on maghemite was studied by batch experiments under various experimental conditions. The kinetic adsorption processes were well described by pseudo-second-order model with high correlation coefficient. The macroscopic results showed that the adsorption of Eu(III) on maghemite significantly decreased with increasing ionic strength, indicating that outer-sphere surface complexation predominated their adsorption of Eu(III). The adsorption isotherms indicated that the removal of Eu(III) adsorption on maghemite were fitted by Freundlish models better than Langmuir and D-R models. The calculated thermodynamic parameters showed that the adsorption of Eu(III) on maghemite was a spontaneous and endothermic process. According to XPS analysis, the high effective adsorption of Eu(III) was mainly attributed to oxygen-containing functional groups of maghemite.