Fabrication of Mesoporous Silica Nanoparticle-Decorated Graphene Oxide Sheets for the Effective Removal of Lead (Pb) from Water.

Mesoporous silica nanoparticle-decorated graphene oxide nanosheets (MSiO-GO) were synthesized and characterized for the active removal of lead (Pb) from the water. MSiO NPs were prepared via an ultrasonication method using tetraethyl orthosilicate (TEOS), and GO sheets were obtained via a modified Hummers' method. X-ray diffraction, UV-vis spectroscopy, Fourier transform infrared spectroscopy, and energy dispersive X-ray spectroscopy specified the composition of MSiO NPs and GO sheets. The surface charge and texture of the MSiO-GO nanosheets were obtained using the ζ-potential technique and by field emission scanning electron microscopy. The relative cytotoxicity test of MSiO NPs and MSiO-GO nanosheets was performed on Murine Raw 264.7 cells before implying the treatment of water. Adsorption of Pb ions on MSiO-GO nanosheets was examined at various parameters such as different aqueous pH values (2.0-10.0), MSiO-GO nanosheet doses (3, 5, 10, 15, 20 mg L), time intervals (2-30 min), and temperatures (25-45 °C). About 90% of Pb ions were removed from water within 30 min (MSiO-GO dose: 15 mg L; initial Pb ions: 50 mg L; temperature: 25 °C; shaking speed: 200 rpm). The maximal uptake of Pb was obtained at solution pH 6.0. Pseudo-first- and pseudo-second-order kinetic rate equations describe the sorption dynamic data. Pb sorption isotherms were modeled using the Freundlich and Langmuir isotherm models. The possible mechanism of binding of Pb ions onto MSiO-GO nanosheets has been discussed. The exhausted MSiO-GO nanosheets were successfully regenerated using 0.005 M HNO as the desorbing agent.