Influence of nucleating agent addition on the textural and photo-Fenton properties of Fe(III)/SiO2 catalysts

Two Fe-based/SiO2 catalysts have been prepared by a sol-gel method, with or without co-gelation with a modified silicon alkoxide, 3-(2-aminoethylamino)propyltrimethoxysilane (EDAS). The aim was to compare these two materials and to study the influence of EDAS on the catalyst texture and photo-Fenton activity. Physicochemical characterization showed that when EDAS was used, the iron was located inside the silica nanoparticles and was partially arranged in iron oxide clusters. As EDAS is a nucleating agent for silica, the reaction time was shorter in its presence, leading to larger silica nanoparticles. Studies of their behavior in aqueous media showed that the catalyst without EDAS released iron, whereas the catalyst with EDAS did not. This iron release influenced the photo-Fenton activities of the catalysts. p-Nitrophenol was degraded more rapidly with the catalyst without EDAS due to the greater availability of iron. Finally, both Fe/SiO2 catalysts displayed stable catalytic activity for 72 h of operation.