Morphology and adsorption capacity of sodium silicate-based hierarchical porous silica templated on natural rubber: Influence of washing–drying methods

• Sol–gel method involving sodium silicate and natural rubber was used to make HPS.
• The HPS recovery by suction filtration gave the poorest pore interconnectivity.
• The 2D arrangement of SNC (Method C) during drying resulted in the best network.

The effects of washing–drying methods on morphology and pores of hierarchical porous silica produced via calcination of the silica–natural rubber composite are reported. The composite, prepared by a sol–gel method involving sodium silicate and natural rubber, was subjected to different washing–drying protocols: suction filtration followed by drying the composite in paste form (Method A); liquid decantation followed by drying a pile of composite beads (Method B); and liquid decantation followed by drying the composite beads forming a single layer on the bottom of a container (Method C). The different washing–drying methods produced hierarchical porous silica with different morphologies and pore properties. Compared with the other samples, Method C yielded the porous silica with the highest total pore volume and the best pore interconnectivity, as well as the highest equilibrium adsorption capacity for methylene blue. Method A, however, produced the porous silica with the poorest properties.