Water Soluble Schiff Base Functinalized Fe3O4 Magnetic Nano-Particles as a Novel Adsorbent for the Removal of Pb(II) and Cu(II) Metal Ions from Aqueous Solutions

A novel magnetic core–shell nano-adsorbent, Fe3O4@SiO2/Schiff base, with Fe3O4 spheres as the core and silica Schiff base as the shell, was prepared. Schiff base in this work is a water soluble Schiff base. The surfaces of magnetite nano-particles were successfully modified by the suitable deposition of silica onto the nano-particle surface. Next, nano-composite surface was functionalized with –NH2 groups by 3-amino propyl triethoxy silane. In the next step, a water-soluble aldehyde (sodium salicylaldehyde-5-sulfonate) was synthesized and characterized. Water-soluble schiff-base supported on the coated magnetite was synthesized by the condensation reaction between the –NH2 groups of functionalized MNPs and carbonyl group of aldehyde. Nano-composite was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry and Thermo-gravimetric analysis. This nano-composite showed a high adsorption capacity for the removal of Pb(II) and Cu(II) metal ions from the aqueous solutions. The experimental data for the adsorption of Pb(II) and Cu(II) were found to follow the Langmuir isotherm and the maximum adsorption capacity were obtained 142.86 mg g−1 (0.69 mmol g−1) and 55.56 mg g−1 (0.87 mmol g−1) for pb(II) and Cu(II) metal ions respectively at pH 5. Noticeably, because the surface of MNPs has been functionalized by a water-soluble Schiff base, the nano-adsorbent dispersed easily without using the shaker or ultrasonic.