silicaThe sodium silicate prepared above was used to prepare theporous silica. Three different methods were employed to induce gelformation: adding HCl solution (Method I), mixing with acidic ionexchange resin (Method II), and adding acidic PEG solution (MethodIII). For the latter case, there were two methods to remove PEG fromthe silica-PEG hybrid to form porous silica: calcination (Method IIIa)and solvothermal extraction (Method IIIb).