Kinetics of palladium nano-particles catalyzed reduction of Methylene Green by hydrazine: Role of induction period in determining mechanistic pathway

摘要: Abstract Methylene Green (MG), a thiazine dye, is catalytically reduced by N2H4 in presence of palladium nano-particles (Pdn) buffer media. The observed rate, ko increases with increase [Pdn], [N2H4] and pH but decrease ionic strength (maintained NaNO3). Unlike other dyes, the catalyzed reduction MG shows an induction period which caused restructuring Pdn surface. rate adsorbate-induced surface independent [MG], suggest that only adsorbed on during reaction. Interestingly, NO3− ions are also turn negatively charged. reductant, this charged before it reacts MG. energy Pdn, though constant (78.8 ± 1.6 kJ M−1) over temperature range 288–313 K activation for varies temperatures. convex Arrhenius plot illustrates different lower (288–304 K, 123.8 ± 12.6 kJ M−1) higher (304–313 K, 69.2 ± 2.1 kJ M−1) around inversion temperature, Tinv (304 K) change nature transition state takes place.