Fe³⁺/Iron Oxide/SiO₂ Xerogel Catalysts for p-nitrophenol Degradation by Photo-Fenton Effects: Influence of Thermal Treatment on Catalysts Texture

Three iron xerogel catalysts were synthesized by hydrolysis and condensation of tetraethoxysilane (TEOS) and 3-(2-aminoethylamino)propyltrimethoxysilane (EDAS) which is able to form a chelate with iron ions. Four thermal treatments were applied to catalysts: drying, drying-autoclaving, calcination and calcination-autoclaving. Textural characterizations show that the specific surface area is increased by calcination while materials microporosity completely collapse when using autoclaving. Based on Mössbauer spectroscopy and magnetometry measurements, only Fe³⁺ species were observed in xerogel catalysts. The photo-Fenton effect of these catalysts was evaluated on the degradation of p-nitrophenol in aqueous media. In the presence of H₂O₂, results show that this effect reachs 99% of degradation after 24 h. Mössbauer and catalytic tests are presented in another paper.