Total Oxidation of Oxytetracycline in a Heterogeneous Fenton System Based on Micro- and Nanocrystals of Fe-Silicalite-1

Two types of Fe-silicalite-1 catalysts were synthesized: microcrystals (4–6 μm, via hydrothermal treatment) and nanocrystals (20–50 nm, via steam-assisted crystallization). It was demonstrated that oxytetracycline adsorbed on the external crystal surface, and the experimental Langmuir approximation agreed with the theoretical data based on crystal geometry. Although both catalysts exhibited equal activities in H2O2 decomposition, the nanocrystalline Fe-silicalite-1 achieved a higher degree of mineralization due to its different textural properties. Moreover, the nanocrystalline sample provided an H2O2 utilization efficiency approximately 90% higher than that of the microcrystalline sample.