The sonochemical insertion of nanomaterials into mesostructures

Ultrasound radiation has been recently used for the synthesis of mesoporous materials (MSPM). The main advantages are manifested in the short preparation time and thicker walls leading to a more hydrothermally stable structure.¹ This preparation method has already been reviewed.² The discovery of MSP materials led immediately to the development of many experimental methods for the deposition of materials, especially catalytic materials, into the mesopores. Impregnation, thermal spreading, ion adsorption, and the most recent method³ in which colloidal gold solution is premixed with the precursors for the preparation of the MSPM, are among the methods used for the insertion of materials into the mesopores. Sonochemistry was also employed for this purpose. We will outline in this article the use of the sonochemical processes for the insertion of nanomaterials into the pores of MSPM. We will explain how this process is conducted, to what extent the materials are deposited in the pores and what is the mechanism for the insertion. An example will be given for the preparation of Ru/MSP TiO₂ and its application as a catalyst in the wet air oxidation of succinic acid and acetic acid, which often appear as the ultimate intermediates in oxidation of many organic pollutants.