Effective removal of Cd(II) from aqueous solution by MnFe2O4 composite modified by surfactant

In this study, the CTAB/MnFe2O4/MnO2 and MnFe2O4/MnO2 composites were prepared using the co-precipitation method. Fourier-transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, and Brunauer-Emmett-Teller method were employed to characterize their morphology and structure. Furthermore, the selective adsorption properties of Cd(II) were investigated under different conditions. The findings support the hypothesis that the optimal adsorption pH for Cd(II) is 6. The adsorption process as a whole fits well the pseudo-second-order kinetic model, and the intraparticle diffusion model is not the only rate-controlling step that is greatly influenced by the film diffusion process. The Langmuir isotherm model of monolayer adsorption behavior describes well the removal of Cd(II) via adsorption onto the MnFe2O4 composites. According to the Dubinin-Radushkevich model, the adsorption of Cd(II) by CTAB/MnFe2O4/MnO2 is chemisorption in nature. The effects of competing ions on Cd(II) adsorption using CTAB/MnFe2O4/MnO2 are as follows: Ca(II) > Mg(II) > Na(I). The promoting effect of organic acids on Cd(II) follows the order of citric acid > tartaric acid > oxalic acid. As a result, the modified MnFe2O4 composite is a potential adsorbent for Cd(II) ion removal from aqueous solutions.