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 4

The morphology of RHA-SiO₂ nanomaterial with different volume ratios of NH₄OH : ethanol: (h) 0 : 0; (i) 0 : 15; (j) 3 : 12; (k) 6 : 9; (l) 9 : 6; (m) 12 : 3; (n) 15 : 0.