Removal of hexavalent chromium from aqueous solutions using Ni–SiO$$₂$$ nanomaterials

This study describes an effective method developed for the removal of hexavalent chromium, Cr(VI), from an aqueous environment. In this study, the Ni–(hbox {SiO}_{{2}}) nanomaterial was synthesized by the sol–gel method and then characterized by field emission scanning electron microscopy, X-ray diffraction and energy dispersive X-ray spectroscopy. The prepared nanomaterial was then employed as an adsorbent with significant properties of high surface area and uptake capacity. Adsorption conditions of Cr(VI) onto the Ni–(hbox {SiO}_{{2}}) nanomaterial were optimized by altering different parameters (pH, initial Cr(VI) concentration and different periods of time). An amount of 100.75 mg (hbox {g}^-1) was estimated as the maximum uptake capacity of the Ni–(hbox {SiO}_{{2}}) nanomaterial at pH 4.0. The experimental data of Cr(VI) adsorption onto the Ni–(hbox {SiO}_{{2}}) nanomaterial were fitted well to the Langmuir isotherm and pseudo second-order kinetic models. Moreover, the adsorption of Cr(VI) onto the Ni–(hbox {SiO}_{{2}}) nanomaterial was not influenced even in the presence of different coexisting ions. Finally, the recommended methodology was applied on several environmental water samples.