A novel and facile green synthesis of SiO2 nanoparticles for removal of toxic water pollutants

The development of a facile synthesis route for highly efficient nanomaterials is one of the key research areas in modern technology. The present study demonstrates a novel and facile green synthesis of SiO2 nanoparticles (NPs) using a simple extraction and precipitation method. This green synthesis method reduces the energy requirement as compared to other green routes mentioned in the literature. The SiO2 NPs synthesized were further amine-functionalized (A-SiO2) to study the effect of surface modification on the adsorption properties of these NPs. The NPs were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV–visible spectroscopy, and Brunauer–Emmett–Teller analyses. The adsorption of water pollutants (Cu2+ and NO3−) was studied on SiO2 NPs before and after amine functionalization because of functionalized interface-assisted adsorption phenomenon. The maximum adsorption capacity (Qm) of SiO2 NPs for Cu2+ and NO3− was found to be 121.95 mg/g and 9.46 mg/g respectively. While the Qm of A-SiO2 for Cu2+ and NO3− was found to be 196.70 mg/g and 23.36 mg/g respectively. A-SiO2 NPs exhibit enhanced adsorption removal efficiency for the water pollutants. Moreover, the effect of various experimental parameters like contact time, NPs concentration, and pH of the solution on the adsorptive removal of pollutants along with the recyclability of SiO2 NPs have been investigated. Results have been discussed in view of Langmuir, Freundlich, and Temkin isotherms.