The FTIR spectrum of the silica particles from calcination of rice hull is shown in Figure 67 1b. A small band at 3440 cm-1 was due to the adsorbed water molecules on the surface of the 68 silica. The intensity of this band decreased when the temperature of calcination increased [7]. 69 At 1092 cm-1, the huge band indicated asymmetric vibration of the siloxane bond, Si-O-70 Si,which was the backbone of the silica. A band presenting at 800 cm-1 corresponded to the 71 stretching vibration of Si-O-Si bond [8]. Due to the bending vibration of the Si-O-Si bond, 72 the clear band was also observed at 472 cm