Synthesis of Nano-silica Oxide for Heavy Metal Decontamination from Aqueous Solutions

Abstract

In the current study, nano-silica oxide (nano-SiO 2 ) was fabricated via the sol-gel technique. Then, the prepared nano-SiO 2 was characterized using X-ray diffractometer (XRD), transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET) specific surface area analysis. Furthermore, the fabricated nano-SiO 2 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 (0–180 min), initial pH (1–11), nano-SiO 2 dose (0.1–8 g L −1 ), initial metal ion concentration (5–100 mg L −1 ), and the temperature (30–85 °C) was investigated. The nano-SiO 2 doses 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 82.3% and 78.5% for Pb (II) and Cr (VI), after 60 and 90 min, at initial pH values of 5 and 2, respectively, using 10 mg L −1 initial metal 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 nature of the adsorption process. These results reveal the efficiency of the fabricated nano-SiO 2 as an adsorbent for heavy metal removal from aqueous solutions. Graphical Abstract

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