Adsorption of Pb(II) from aqueous solutions by montmorillonite/Fe3O4 nanoparticles: batch and column studies

Abstract

In the present study, magnetic montmorillonite (MMT/Fe3O4) was prepared using chemical precipitation for adsorption of Pb(II) and was characterized by scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, X-ray diffraction and Fourier-transform infrared spectroscopy (FTIR). The results showed that Fe3O4 uniformly occurred on MMT. The maximum adsorption capacity of Pb(II) by MMT/Fe3O4 was obtained to be 36.76 mg/g, which was higher than the Fe3O4 and MMT alone. The removal efficiency of Pb(II) was strongly dependent on the operating factors, where the maximum efficiency occurred at pH of 5, adsorbent dose of 0.4 g/L, Pb(II) concentration of 30 mg/L, stirring rate of 300 rpm, and contact time of 120 min. The adsorption data followed the Langmuir isotherm, and the kinetic results showed that the chemisorption process is the dominant mechanism for Pb(II) removal. The results of the FTIR analysis explained that the Al–OH and Fe–O functional groups have high participation in pollutant adsorption. The column study emphasized that MMT/Fe3O4 nanocomposite has excellent efficiency in the treatment of real wastewater containing Pb(II). In addition, excellent magnetic separation and regeneration performance indicated the applicability of adsorbent for the treatment of synthetic and real solutions.