Radiolysis of Reactive Azo Dyes in Aqueous Solution

Abstract

RADIOLYSIS OF REACTIVE AZO DYES IN AQUEOUS SOLUTION. The effects of radiation on aerated reactive dye solutions i.e Cibacron Violet, Cibacron Orange and Cibacron Yellow solutions have been studied. Parameters analysis were the change of pH after radiation, the change of absorption, degradation products and effects of pH on the radiolysis. The uv-vis absorption of solutions were observed before and after irradiation. pH variation was done from pHs 3, 5, 7, 9 and 12. Irradiation was done at doses of 0, 2, 4, 6, 8 and 10 kGy with dose rate of 5 kGy/h and was determined by a Fricke dosimeter. HPLC with UV detector was used to analyze the degradation products. Oxalic acid was the main degradation product and small amount of succinic acid was also detected.

Radiation induced degradation of dyes—An overview

“…In the presence of dissolved oxygen, the hydrogen atom would react rapidly with oxygen, leading to the formation of the highly oxidizing hydroperoxy radicals ( • HO 2 ), as shown below [89]:…”

“…One such study by Agustin et al [89] on the degradation of dyes at different pH values was carried out by irradiating different aqueous dye solution to a dose of 0, 2, 4, 6, 8 and 10 kGy. Surprisingly, the authors found the effect of pH to be very structure and radiation dose dependent.…”

Modeling the mineralization and discoloration in colored systems by (US)Fe2+/H2O2/S2O82− processes: A proposed degradation pathway

“…As it can be seen, oxalic acid is considered to be a main product [27]. Formation of oxalic acid was confirmed by HPLC analysis.…”

“…As presented and discussed in several papers [26][27][28][29], degradation of azo dyes can be described by the following stages ( Fig. 2): (i) azo bond breakdown that includes lose of saturated character of azo bond and transformation to hydroxyl structure, (ii) tearing the dye molecule (cleavage of -N-N-bond and nitro group formation) when differently substituted aromatic compounds (benzene, naphthalene, and triazine) are produced, (iii) degradation of aromatic rings; naphthalene to benzene, benzene to carboxylic acids, alcohols and aldehydes, with an emphasis on oxalic acid; and oxidation of substituted triazines to cyanuric acid, and finally, (iv) oxidation of oxalic acid to CO 2 by hydroxyl and sulfate radical.…”

A Study on Dosimetric Characterization of Direct Yellow 12 Dye at High Radiation γ-Dose

“…Two dyes Cibacron Violet and Cibcron Golden Yellow showed decrease in degradation in pH range from 3 to 9 at high pH values. 4 The absorption of Direct yellow 12 dye solution at pH 7, 5.5 and 12.5 showed gradual increase with radiation absorbed dose as shown in Figure 2. The enhanced absorbance of dye solutions may be due to the regeneration of dye molecules in the reaction media.…”