Separation of Spherical Nanosilica from Agricultural Wastes in Vietnam via Ultrasonic-Assisted Precipitation and Application for Effective Removal of Methylene Blue from Aqueous Solution

Figure 5

The morphology of pure-SiO₂ nanomaterial with different volume ratios of NH₄OH : ethanol: (o) 0 : 0; (p) 0 : 15; (q) 3 : 12; (r) 6 : 9; (s) 9 : 6; (t) 12 : 3; (u) 15 : 0.