Synthesis and Characterization of SiO[sub.2] Nanoparticles for Application as Nanoadsorbent to Clean Wastewater

By way of the sol–gel chemical synthesis method, it is possible to synthesize SiO[sub.2] nanoparticles with a defined specific particle size, a surface area, and a defined crystal structure that can be effectively used as a nanoadsorbent to remove various organic dyes. SiO[sub.2] nanoparticles were synthesized by the sol–gel method using sodium silicate (Na[sub.2]SiO[sub.3]) by a green method without using a tetraethyl orthosilicate (TEOS) precursor, which is very expensive and highly toxic. This sol–gel process involves the formation of a colloidal suspension (sol) and solid gelation to form a network in a continuous liquid phase (gel). In addition, it requires controlled atmospheres. XRD indicates the presence of an amorphous phase with a diffraction angle of 2θ = 23°, associated with SiO[sub.2]. UV-Vis spectroscopy reveals an absorbance value in the region of 200 nm to 300 nm, associated with SiO[sub.2] nanoparticles. The application as a nanoadsorbent to remove dyes was measured, and it was found that the nanoparticles with the best performance were those that were synthesized with pH 7, showing a 97% removal with 20 mg of SiO[sub.2] nanoparticles in 60 min. Therefore, SiO[sub.2] nanoparticles can be used as a nanoadsorbent, using a low-cost and scalable method for application to remove methylene blue in an aqueous medium.