Combined Layer-by-Layer/Hydrothermal Synthesis of Fe 3 O 4 @MIL-100(Fe) for Ofloxacin Adsorption from Environmental Waters.

A simple not solvent and time consuming Fe 3 O 4 @MIL-100(Fe), synthesized in the presence of a small amount of magnetite (Fe 3 O 4 ) nanoparticles (27.3 wt%), is here presented and discussed. Layer-by-layer alone (20 shell), and combined layer-by-layer (5 shell)/reflux or /hydrothermal synthetic procedures were compared. The last approach (Fe 3 O 4 @MIL-100_H sample) is suitable (i) to obtain rounded-shaped nanoparticles (200-400 nm diameter) of magnetite core and MIL-100(Fe) shell; (ii) to reduce the solvent and time consumption (the layer-by-layer procedure is applied only 5 times); (iii) to give the highest MIL-100(Fe) amount in the composite (72.7 vs. 18.5 wt% in the layer-by-layer alone); (iv) to obtain a high surface area of 3546 m 2 g -1 . The MIL-100(Fe) sample was also synthesized and both materials were tested for the absorption of Ofloxacin antibiotic (OFL). Langmuir model well describes OFL adsorption on Fe 3 O 4 @MIL-100_H, indicating an even higher adsorption capacity (218 ± 7 mg g -1 ) with respect to MIL-100 (123 ± 5 mg g -1 ). Chemisorption regulates the kinetic process on both the composite materials. Fe 3 O 4 @MIL-100_H performance was then verified for OFL removal at µg per liter in tap and river waters, and compared with MIL-100. Its relevant and higher adsorption efficiency and the magnetic behavior make it an excellent candidate for environmental depollution.