603481.fig.004a
(a)
603481.fig.004b
(b)
603481.fig.004c
(c)
603481.fig.004d
(d)
Figure 4: TG of rice husk and residues (a) and analysis of ultrafine silica; XRD (b); adsorption-desorption isotherms (c); differential pore size distribution (d).