Nanocomposite of montmorillonite and silver nanoparticles: Characterization and application in catalytic reduction of 4-nitrophenol

• Published in: Materials chemistry and physics 2013-07, Vol.140 (2-3), p.493-498
• Main Authors: Praus, Petr, Turicová, Martina, Karlíková, Martina, Kvítek, Libor, Dvorský, Richard
• Format: Article
• Language: English
• Subjects: A. Composite materials; A. Metals; A. Microporous materials; A. Nanostructures; D. Optical properties; D. Surface properties
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2013.03.059

Silver ions previously intercalated into a montmorillonite (MMT) interlayer were reduced by sodium borohydride forming a nanocomposite of MMT and silver nanoparticles (Ag–MMT) with no other stabilizing additives. Within 360 min no coagulation of an aqueous Ag–MMT dispersion was observed. However, after 24 h the coagulation was indicated by a red shift of absorption maximum from 408 nm to 434 nm and by broadening of the absorbance band. The nanocomposite was characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and measurements of specific surface area (SSA). It contained 4.94 wt. % of silver. Ag nanoparticles with an average size of 6.9 nm were located on the external MMT surface, mostly in its pores. Ag–MMT was used as a catalyst for reduction of 4-nitrophenol with sodium borohydride forming 4-aminophenol. After 30 s the reaction kinetics changed from zero order to first order, which was explained by means of the Langmuir–Hinshelwood model. The whole reduction was completed after 290 s. During this time min. 95 wt. % of Ag nanoparticles stayed fixed on the MMT support. •Ag nanoparticles with an average size of 6.9 nm were reduced on montmorillonite.•Ag nanoparticles were fixed in montmorillonite pores forming a stable nanocomposite.•Ag in the nanocomposite showed catalytic activity for reduction of 4-nitrophenol.•Reaction kinetics was explained by the Langmuir–Hinshelwood model.