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Title: Nanoparticle mediated copper(II) catalyzed oxidation of mercaptosuccinic acid by methylene blue in aqueous acetone medium: Non-Arrhenius behaviour
Authors: Pal, Mahender
Shukla, Maya
Sharma, Ranjana
Mishra, K K
Keywords: Kinetics;Nanocatalysis;Nanoparticles;Oxidation;Non-Arrhenius behaviour;Copper;Mercaptosuccinic acid;Methylene blue
Issue Date: 21-Oct-2015
Publisher: NISCAIR-CSIR, India
Abstract: The oxidation of mercaptosuccinic acid by methylene blue catalyzed by Cu(II) (ca. 2.0×10-5 M) in acidic medium leads to the formation of the corresponding disulphide and leuco dye. A half order kinetics is followed in methylene blue while the order in the substrate varies between half and unity. The rate constant increases linearly on increasing [Cu(II)] while remaining unaffected on varying [H+]. At lower concentrations of hydrogen ion, however, the reaction exhibits zero order kinetics in methylene blue. The reaction shows a non-Arrhenius behaviour between 20 °C and 30 °C but subsequently the rate constant increases at 35 °C and attains a limiting value. The rate of reaction increases on increasing the time of incubation of the catalyst. TEM, SEM, XRD and FTIR data indicate the participation of copper nanoparticles and XRD analysis suggests the population of (100), (111), (210) and (211) planes at 35 °C. A new active facet, (200), is created in the face centered cubic lattice of Cu on increasing the time of incubation. The non-Arrhenius behaviour is attributed to the temperature dependent changes in size and morphology of the nanoparticles and to a variation in the Fermi band gap energy.
Page(s): 1183-1191
ISSN: 0975-0975(Online); 0376-4710(Print)
Appears in Collections:IJC-A Vol.54A(10) [October 2015]

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