SiO2–TiO2 xerogels for tailoring the release of brilliant blue FCF

Xerogels consisting of SiO2 and TiO2 were explored for controlled release of brilliant blue FCF (BBF). Both SiO2 and SiO2–TiO2 xerogels were prepared by way of sol–gel processing, and the BBF release behavior was compared. SiO2–TiO2 xerogels with varying TiO2 content were also studied and the BBF release behavior was determined for each SiO2–TiO2 xerogel. It was found that the release of BBF from SiO2 xerogels can be increased by the addition of TiO2 content, and the amount and rate of BBF released from the SiO2–TiO2 xerogels can be changed by modifying the amount of TiO2 included during the preparation of the xerogels, where the SiO2–TiO2 xerogels with a higher content of TiO2 released a higher fraction of BBF in water media when compared to the release from SiO2–TiO2 xerogels with lower amounts of TiO2. The experimental results have to be explained by a combination of porous structure, in situ dissolution–condensation during the BBF elution and the change of surface chemistry of the xerogel network with the addition of TiO2.