Mesoporous silicas prepared from sodium silicate using gelatin templating

Gelatin was employed as a templating agent for the preparation of mesoporous silica materials starting from sodium silicate solutions using a sol-gel method. The silicate anions were first transformed into silicic acid by passing the solution through an H+ ion-exchange resin, then mixed with acidic gelatin solution prior to adjustment of the pH to approximately 9-10. Gelatin was removed by solvothermal Soxhlet extraction to form pores. We show that gelatin can serve as a structure-directing agent resulting in silica structures with pores spanning a range of 3-12 nm depending on gelatin concentration. Increasing gelatin concentration resulted in a larger pore size and a wider pore-size distribution. This dependence was also observed for the surface area and pore volume but only at low gelatin concentration (<0.4 wt%). The surface area and the pore volume tended to decrease with increasing gelatin concentration at high gelatin concentration (>0.4 wt%). Mesoporous silica with a high specific surface area (426.6 m2 g-1), high pore volume (0.9 cm3 g-1) and large pore diameter (8.4 nm) was obtained at a gelatin concentration of 0.41 wt%. (C) 2011 Curtin University of Technology and John Wiley & Sons, Ltd.