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Kinetics and mechanism of o-aminophenol oxidation by the supported mesoporous silica (HISiO2) in the binary system with Amberlite resin

Kinetics and mechanism of o-aminophenol oxidation by the supported mesoporous silica (HISiO2) in the binary system with Amberlite resin
Kinetics and mechanism of o-aminophenol oxidation by the supported mesoporous silica (HISiO2) in the binary system with Amberlite resin
HISiO2 (hexagonal mesoporous silica) was synthesized with a high concentration of a non-ionic template. The synthesized HISiO2 materials have a well defined porous architecture with surface area (760 m2 g?1), and pore SIZE=35 Å. Cu(II)–aquo complex was anchored onto silica (S–CuII) through the coordination with amino-functionalized HISiO2 (S–NH2) without impregnation on the surface. The oxidation of o-aminophenol (o-AP) with (S–CuII), Cu(II)-oxalate complex supported on Amberlite resin (R–CuII), (R–CuII)/S–NH2 (0.05 g), and a mixture (1:1) of (R–CuII)/(S–CuII), has been studied at different temperatures (25–40 °C) ±0.1. The oxidation product has been monitored kinetically and spectrophotometrically. All redox reactions were characterized by first-order kinetics. The rate constant of the oxidation reaction of o-AP decreases in the following order; (S–CuII)>(R–CuII)/(S–CuII)>(R–CuII)/(S–NH2)>(R–CuII). This sequence reflects the role of the effective surface area of HISiO2 on the redox reaction. The activation parameters for the amine oxidation have been estimated. Besides, a mechanism of the oxidation process of o-AP has been proposed.
hexagonal mesoporous silica, amberlite anion-exchanger, o-aminophenol, copper-complexes, synthesis, oxidation, kinetics, liquid-crystal templates, mcm-41 type silicas, molecular-sieves, aromatic-amines, electron-transfer, aqueous-solution, synthase model, pore-size, complexes, dioxygen
217-228
El-Safty, S.A.
135100ff-4103-4888-9523-b7a90a1e2b8c
Evans, J.
05890433-0155-49fe-a65d-38c90ea25c69
El-Sheikh, M.Y.
284e12f9-13ec-4f5c-a8f3-3c68e5283bbe
Zaki, A.B.
d60241c5-b639-4714-ab0f-6aefe73a34cc
El-Safty, S.A.
135100ff-4103-4888-9523-b7a90a1e2b8c
Evans, J.
05890433-0155-49fe-a65d-38c90ea25c69
El-Sheikh, M.Y.
284e12f9-13ec-4f5c-a8f3-3c68e5283bbe
Zaki, A.B.
d60241c5-b639-4714-ab0f-6aefe73a34cc

El-Safty, S.A., Evans, J., El-Sheikh, M.Y. and Zaki, A.B. (2002) Kinetics and mechanism of o-aminophenol oxidation by the supported mesoporous silica (HISiO2) in the binary system with Amberlite resin. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 203 (1-3), 217-228. (doi:10.1016/S0927-7757(01)01102-5).

Record type: Article

Abstract

HISiO2 (hexagonal mesoporous silica) was synthesized with a high concentration of a non-ionic template. The synthesized HISiO2 materials have a well defined porous architecture with surface area (760 m2 g?1), and pore SIZE=35 Å. Cu(II)–aquo complex was anchored onto silica (S–CuII) through the coordination with amino-functionalized HISiO2 (S–NH2) without impregnation on the surface. The oxidation of o-aminophenol (o-AP) with (S–CuII), Cu(II)-oxalate complex supported on Amberlite resin (R–CuII), (R–CuII)/S–NH2 (0.05 g), and a mixture (1:1) of (R–CuII)/(S–CuII), has been studied at different temperatures (25–40 °C) ±0.1. The oxidation product has been monitored kinetically and spectrophotometrically. All redox reactions were characterized by first-order kinetics. The rate constant of the oxidation reaction of o-AP decreases in the following order; (S–CuII)>(R–CuII)/(S–CuII)>(R–CuII)/(S–NH2)>(R–CuII). This sequence reflects the role of the effective surface area of HISiO2 on the redox reaction. The activation parameters for the amine oxidation have been estimated. Besides, a mechanism of the oxidation process of o-AP has been proposed.

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More information

Published date: 25 April 2002
Keywords: hexagonal mesoporous silica, amberlite anion-exchanger, o-aminophenol, copper-complexes, synthesis, oxidation, kinetics, liquid-crystal templates, mcm-41 type silicas, molecular-sieves, aromatic-amines, electron-transfer, aqueous-solution, synthase model, pore-size, complexes, dioxygen

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Local EPrints ID: 19724
URI: http://eprints.soton.ac.uk/id/eprint/19724
PURE UUID: 44dd7302-ab2e-4964-a2f0-7887dfc7f76f

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Date deposited: 17 Feb 2006
Last modified: 08 Jan 2022 12:49

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Contributors

Author: S.A. El-Safty
Author: J. Evans
Author: M.Y. El-Sheikh
Author: A.B. Zaki

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