Transformation of iron nitrate into iron nanoparticles embedded in mesoporous silica molecular sieve SBA-15 nanostructures by ultrasonication and microwave irradiation

Regular iron nanoparticles embedded in mesoporous silica molecular sieve SBA-15 walls are synthesized using classic impregnation modified by ultrasonication and a microwave procedure. Iron nanoparticles in mesoporous silica molecular sieve of a regular honeycomb structure are prepared by using mesoporous silica molecular sieve SBA-15 as a support and iron nitrate as an iron precursor. The characteristics of the material are investigated using several methods such as energy nitrogen adsorption-desorption, small angle X-ray diffraction (SA-XRD), energy dispersive X-ray (EDAX), Fourier transformation infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). The results show that the iron-incorporation process does not significantly change the structure of the mesoporous silica molecular sieve materials after calcination at 700°C. However, ultrasonication and microwave treatment during the impregnation process enhance the affinity between the silica and the functional iron groups leading to silanol formation. The addition of iron after ultrasonication leads to a large content of iron in the mesoporous silica molecular sieve and silanol groups during calcination. The microwave treatment increases the iron content with the temperature increase during the calcination. A regular mesostructures' destruction occurs due to fast thermal reactions between silica and oxygen during the calcination at 700°C.