Synthesis of nano-silica oxide for heavy metals decontamination from aqueous solutions

Abstract

In the current study, nano-silica oxide (nano-SiO2) was fabricated via the sol-gel technique. Then, the prepared nano-SiO2 was characterized using X-ray diffractometer (XRD), transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), and Brunauer-Emmett-Teller. Furthermore, the fabricated nano-SiO2 was applied for the adsorption of lead Pb (II) and chromium Cr (VI) from aqueous solutions. Additionally, the influence of different operating factors such as contact time, nano-SiO2 dose, initial pH, initial metal ions concentration, and the temperature was investigated. The nano-SiO2 dosages of 0.5 and 1 g L-1 were selected as the optimal adsorbent dose for the removal of Pb (II) and Cr (VI), respectively. These doses achieved a removal efficiency of 83.29% and 78.65% for Pb (II) and Cr (VI), after 60 and 90 min, respectively, (at initial pH values of 7, using 10 mg L-1 initial metals concentration, and at room temperature). Lastly, kinetic and equilibrium studies were competently fitted using the pseudo-second-order and Freundlich models, respectively. Adsorption thermodynamic studies designate the spontaneous and thermodynamic of the adsorption processes nature. These results reveal the efficiency of the fabricated nano-SiO2 as an adsorbent for heavy metals removal from aqueous solutions.