Homogeneous Palladium Nanoparticles Surface Hosts Catalyzed Reduction of the Chromophoric Azo (-N=N-) Group of Dye, Acid Orange 7 by Borohydride in Alkaline Media

摘要

In alkaline media, well-characterized gelatin-stabilized palladium (GPd) nanoparticles catalyze the reduction of the azo group containing pollutant dye, Acid Orange 7 (AO7) by sodium borohydride (NaBH4) to 1-amino-2-napthol and sulfanilic acid. Kinetic observations and detailed FTIR studies suggests that the reaction follows Langmuir-Hinshelwood kinetic model, where during the reaction both AO7 and borohydride are adsorbed on the GPd surface. Plots of Ink_o versus ln[AO7] or ln(NaBH4] show that the order of reaction with respect to A07 and NaBH4 remains almost same over different molar ratios of [NaBH4[/[AO7]. The catalyzed reaction shows an initial induction period (to) due to a surface-restructuring process of GPd nanoparticles, and (1/t0) can be defined as the rate of surface restructuring. The activation energy of the catalyzed reaction and energy of the surface-restructuring process of GPd are estimated as 22 ± 3 and 25 ± 7 kJ M~(-1), respectively.