Enhanced adsorption and stability of aspirin molecules on magnetite a-Fe2O3/MCM-41 composites

Abstract

In this work, magnetic mesoporous silica (a-Fe2O3/MCM-41) composites were prepared by incipient-wetness impregnation and direct hydrothermal methods, while their drug adsorption properties were investigated by using aspirin as the model of the drug. As for the characterization results, X-ray diffraction patterns (XRD) and diffuse reflectance ultraviolet-visible (DR UV-Vis) spectra revealed that hematite nanoparticles were successfully incorporated into the mesoporous network of MCM-41. The adsorption capacity towards aspirin over the prepared a-Fe2O3, MCM-41, and a-Fe2O3/MCM-41 composites was investigated by monitoring the absorption wavelength of aspirin at 226 nm using UV spectroscopy. It was obtained that aspirin was not stable and converted to salicylic acid when using bare a- Fe2O3. On the other hand, the aspirin breakdown was not observed when using MCM-41 and a-Fe2O3/MCM-41 composites as the adsorbents. The adsorption capacity of the MCM-41 was found to be significantly improved when the a-Fe2O3 was incorporated into the mesoporous network. This result demonstrated the importance o f both the MCM-41 support and the dispersion a-Fe2O3 to get enhanced adsorption and stability of the aspirin. Under the same condition, all of the hydrothermally prepared composites showed significantly higher amount of adsorbed aspirin as compared to the composites prepared by impregnation method. Since the hexagonal mesoporous structure of the composites prepared by hydrothermal method was maintained better than that prepared by the impregnation method, it was proposed that the ordered structure of the MCM-41 support played important role in the adsorption o f aspirin.