Utilization of tin and titanium incorporated rice husk silica nanocomposite as photocatalyst and adsorbent for the removal of methylene blue in aqueous medium

A series of tin and titanium incorporated rice husk silica have been synthesized via sol–gel method using cetyltrimethylammonium bromide as the structure directing agent. The samples were labeled as RHA-Silica, RHA-10Sn, RHA-10Ti, and RHA-10Sn10Ti. The BET specific surface areas of these catalysts were found to be 315, 607, 439 and 255 (m2 g−1) with type IV isotherms, respectively. The catalysts were found to be X-ray amorphous and the particle size was found to be in the nano range. Calcination of RHA-10Sn at 500 °C gave silica–tin nanotubes. RHA-10Sn10Ti showed the highest activity in the photocatalytic degradation of methylene blue (MB). The adsorption of MB on these catalysts was found to fit the pseudo-second order kinetic model. The adsorption rate was found to be strongly dependent on the pH of the solution.