Synthesis and structural characterization of magnetite/sepiolite composite and its sorptive properties for Co(II) and Cd(II)

• Magnetic/sepiolite composite was synthesized by chemical co-precipitation method.
• The products have preferable saturation magnetization (16.85 A/m2/kg).
• Sorption behavior had been studied for the Co(II) and Cd(II).
• The products remain higher sorption capacity toward Co(II) and Cd(II).

In this work, the magnetite/sepiolite (M/SEP) composite was synthesized by chemical co-precipitation method and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer (VSM). The characterization results showed that M/SEP was composed of magnetite and sepiolite and had a superparamagnetic property. Considering the good separation characteristic after use, M/SEP composite was used as a sorbent for the removal of Co(II) and Cd(II) from aqueous solutions. The pH and temperature on Co(II) and Cd(II) sorption to M/SEP composite were investigated. The results showed that the sorption of Co(II) and Cd(II) was strongly dependent on pH, and the Langmuir sorption capacities of M/SEP composite for Co(II) and Cd(II) were 18.85 and 14.15 mg/g at 20 ºC, respectively. The thermodynamic parameters indicated that the sorption processes of Co(II) and Cd(II) on M/SEP composite were endothermic and spontaneous processes. Herein, this finding suggests that M/SEP composite can be applied on the preconcentration of heavy metal ions in the field of water treatment.

From the figure, it is clear that the Langmuir model simulates the experimental data better than the Freundlich model for sorption of Co(II) and Cd(II) on M/SEP. The Langmuir isotherm indicates that monolayer coverage of the sorbent particles is the main sorption process.Figure optionsDownload as PowerPoint slide