Homogeneous and heterogeneous catalytic oxidation of some azo dyes using copper(II) ions

Ibrahim A Salem; Mohamed H Shaltout; Ahmed B Zaki

doi:10.1016/j.saa.2019.117618

Homogeneous and heterogeneous catalytic oxidation of some azo dyes using copper(II) ions

Spectrochim Acta A Mol Biomol Spectrosc. 2020 Feb 15:227:117618. doi: 10.1016/j.saa.2019.117618. Epub 2019 Oct 22.

Authors

Ibrahim A Salem¹, Mohamed H Shaltout², Ahmed B Zaki³

Affiliations

¹ Chemistry Department, Faculty of Science, Tanta University, Tanta, Egypt. Electronic address: dr.ibrahimsalem@science.tanta.edu.eg.
² Reference Laboratory of Drinking Water, Holding Company of Drinking Water and Waste Water, Cairo, Egypt. Electronic address: mhshaltout@hotmail.com.
³ Chemistry Department, Faculty of Science, Tanta University, Tanta, Egypt.

PMID: 31699590
DOI: 10.1016/j.saa.2019.117618

Abstract

The kinetics of the homogeneous and heterogeneous catalytic oxidation processes of three azo dyes in presence of copper (II) - ions, copper (II) - ions - supported on alumina and on zinc oxide as well as copper ammonia complex supported on alumina were investigated in aqueous solutions. The dyes are Chromotrope 2B (C2B), Chromotrope 2R (C2R) and Chrysophenen (CRY). The reaction progress was followed by monitoring the decrease in absorbance at ℷmax 512, 511 and 401 nm, respectively. The rate of reaction increased with increasing either the concentration of the dye or the catalyst, giving a plateau at high concentrations of the catalyst. On the other hand, the rate of reaction increased gradually with increasing hydrogen peroxide concentration attaining a maximum then decreased thereafter. The reaction rate was also increased with increasing pH and temperature and was found to be entropy controlled. This work could be applied for dye baths water reuse to reduce costs in textile and dyeing factories as will as for environmental purposes.

Keywords: Alumina; Catalyst; Copper (II) - ions; Heterogeneous; Homogeneous; Hydrogen peroxide; Kinetics; Mechanism.