2.2.2. Treatments Conducted under Non-Stirring Conditions

The second experimental set was conducted to evaluate the feasibility for promoting the one-pot reaction without stirring. The treatments were carried using a 5.0 M KOH solution with two volumes (12.5 and 18.5 mL) for different reaction intervals (3–72 h) and temperatures (200–240 °C). Additionally, some experiments were conducted with different Si⁴⁺ molar contents (2.2–2.8 mole). According to the nominal 3.0 mole Si⁴⁺ (7.5 mL), the lower contents of 2.2, 2.4, 2.6, and 2.8 Si⁴⁺ mole were added proportionally to the volume ratio Si⁴⁺:H₂O of 5.5:2.0, 6.0:1.5, 6.5:1.0, and 7.0:0.5, respectively. After the solution mixing, the autoclave vessel was sealed and heated inside a convection oven to reach the desired temperature. After each treatment, the reaction products were gravimetrically separated and then washed vigorously, four times, with hot water (60 °C) to clean the remaining alkaline medium. Then, the resultant powders were dried overnight in an oven at 80 °C.