Mesoporous Alumina-Titania Composites with Enhanced Molybdenum Adsorption towards Medical Radioisotope Production

This work reports the fabrication of mesoporous Al2O3-TiO2 composites with various contents of TiO2 and their utilization as adsorbents for molybdenum anions with potential application in medical radioisotope production. The increase of TiO2 promotes the deposition of more TiO2 nanoparticles on the surface of the Al2O3 support without altering the original morphology. Furthermore, alumina samples loaded with smaller amounts of TiO2 (Al2O3-2.5% Ti (20.01 mass% TiO2) and Al2O3-5% Ti (34.55 mass% TiO2)) are amorphous in nature. However, at a high loading (Al2O3-10% Ti (63.97 mass% TiO2)), anatase TiO2 becomes the dominant phase, suggesting the extensive coverage of the Al2O3 surface by TiO2 NPs. The TiO2 modification is also observed to greatly increase the surface area from 177 m2 g−1 for pristine γ-Al2O3 to as high as 982 m2 g−1 for Al2O3-5% Ti sample. When employed for molybdenum adsorption, the Al2O3-5% Ti sample displays a higher Mo adsorption capacity (44.5 mg g−1) than Al2O3-2.5%Ti (39.0 mg g−1), Al2O3-10%Ti, (40.5 mg g−1), and pristine γ-Al2O3 (37.1 mg g−1) samples. The larger surface area and presence of additional hydroxyl groups for attracting the molybdenum anions contribute to the enhanced adsorption capacities of the Al2O3-TiO2 composites compared to that of pristine γ-Al2O3.