Preparation and Characterization of Silver Nanoparticles-Magadiite Materials. Application to Reduction of Toxic Organic Dyes

In this work, a layered silicate Na-magadiite was hydrothermally synthesized and used as a starting material to prepare Ag- exchanged magadiites through intercalation reaction with 0.5 M, 1 M and 1.5 M silver nitrate solutions. The obtained Ag-exchanged magadiite samples are then reduced with sodium tetrahydridoborate (NaBH 4 ) to obtain AgNPs-magadiite composites materials with different silver contents. All samples obtained are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV–visible spectroscopy, Scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDX) and thermal (TG) analysis. The results show that the exchange with silver is total and leads to a disorganization of the layered magadiite structure which is recovered again once Ag-magadiite samples are reduced with sodium tetrahydridoborate (NaBH 4 ). Therefore, these analysis methods confirm also the formation of silver nanoparticles (AgNPs) with an average size of about 24 nm in AgNPs-magadiite materials after reduction reactions. Formed by agglomeration of reduced Ag° species which occurs outside the layered structure, these AgNPs species are dispersed in the magadiite solid matrix and are not part of its internal structure. Used as catalysts in the photodegradation of Congo red and Methylene blue dyes in aqueous solutions, the AgNPs-magadiite materials obtained lead to the complete reduction of these pollutants into nontoxic organic compounds.