Simple and Straightforward Synthesis of Porous Ionosilica for Efficient Chromate Adsorption

We report a very simple synthesis strategy for the formation of moderately porous ionosilica materials containing ammonium groups. We synthesized an ionosilica xerogel and an ionosilica aerogel, either via conventional or supercritical work-up. The synthesis scheme of both precursor and ionosilica materials could easily be up-scaled to a 100 g scale. All syntheses and work-up procedures are sustainable as no additional agent and very low quantities of solvents were used, and no additional purifications steps were necessary. Although both materials show excellent anion exchange properties for chromate adsorption, noticeable differences were found regarding the thermodynamics of the exchange process. We attribute these differences to different surface chemistries of the materials, induced by the different work-up procedures. Due to the easy availability of high quantities of material, ionosilicas can be implemented as functional ion exchange materials in larger scale processes, thus opening new fields of applications.