Catalytic oxidation of methylene blue by dendrimer encapsulated silver and gold nanoparticles

• Dendrimer encapsulated Ag and Au nanoparticle were synthesized in aqueous solution.
• Oxidation of methylene blue was performed for the catalytic activity investigation.
• Catalytic oxidation was modeled according to Langmuir–Hinshelwood approach.
• Effect of temperature and concentration were investigated in adsorption process.
• Kinetic and thermodynamic parameters of adsorption process were determined.

The catalytic oxidation of methylene blue was investigated in the presence of dendrimer generation five terminated NH2 encapsulated silver (AgDENs), and gold (AuDENs) nanoparticles as catalyst. The synthesis process of encapsulated metal nanoparticles were monitored by UV/vis spectrophotometry and their average diameters determined by transmission electron microscopy analysis, respectively. The kinetics was monitored using UV/vis spectrophotometry, under pseudo-first order conditions, resulting in observed rate constants kobs. Langmuir–Hinshelwood approach was applied to model the kinetic process. The adsorption of methylene blue on the catalyst surface is related to the type of metal nanoparticle present, and presents the rate-determining step.

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