Synthesis and Characterization of Cerium Molybdate Nanocontainers and Their Inhibitor Complexes

Cerium molybdate nanocontainers were synthesized using a two-step process and then loaded with 8-hydroxyquinoline (8-HQ) or with 1-H-benzotriazole-4-sulfonic acid (1-BSA). First, polystyrene (PS) nanospheres were produced using emulsion polymerization. Second, the PS spheres were coated via the sol–gel method to form a cerium molybdate layer. Finally, the nanocontainers were made by calcination of cerium molybdate coated PS nanospheres. The products were characterized by scanning electron microscopy (SEM/EDX), transmission electron microscopy, FT-infrared (FT-IR) spectroscopy, X-ray diffraction, thermogravimetric analysis (TGA), and differential thermal analysis. Moreover, nanocontainers were loaded with 8-HQ or with 1-BSA and their presence was confirmed with FT-IR. The loading of the inhibitors in the nanocontainers was estimated with TGA. The loading amount of 8-HQ was 5.22% w/w and that of 1-BSA was 16.43%. Based on the size of the nanocontainers and the assumption that they are not broken, we deduced to the amount of approximately with 1.07 × 10⁶ molecules of 8-HQ and 2.35 × 10⁶ molecules of 1-BSA per nanocontainer. Furthermore, release of 8-HQ or 1-BSA in corrosive environment was studied by potentiodynamic measurements for aluminum alloys 2024-T3 (AA2024-T3) and DC01 carbon steel (DC01-CS) samples, showing that the inhibitors are released from the nanocontainers, suppressing the corrosion activities. SEM photographs confirmed that the nanocontainers maintained their shape after suspension in 0.5 M NaCl solution for more than 72 h. Moreover, release of 8-HQ or 1-BSA in water was studied using spectrophotometer.