Analysis of sulphonated azodyes and their degradation products in aqueous solutions treated with a new electrochemical method

Abstract

Aqueous solutions of four sulphonated azodyes, Reactive Orange 91, Reactive Red 184, Reactive Blue 182 and Reactive Black 5, containing 0.2 mol/L of electrolyte were treated in a laboratory scale electrolytic cell with a new electrochemical method intended for the textile wastewater treatment. The electrochemical process was monitored by means of absorbance of UV-Vis light and chemical oxygen demand values. Carbon fleece was used as a cathode, and platinated titanium was used as an anode. Reversed-phase high-performance liquid chromatography coupled with photodiode array and mass spectrometric detectors was applied for the analysis of dyes, their impurities and degradation products after the electrochemical treatment. Dihexylammonium and triethylammonium acetate as ion-pairing reagents, or alternatively ammonium acetate as an ion-exclusion suppressing reagent, were used to improve the separation.

Keywords:

• Azodyes
• Electrochemical treatment
• Liquid chromatography; Mass spectrometry
• Degradation

Acknowledgments

Thanks are due to Texapret SA, Thessaloniki, Greece for the gift of the original azodyes. This work has been funded by project YPER No. 09312, sponsored by the Ministry of Development, General Secretariat of Research and Technology of Greece, by the project No. 203/01/0238 sponsored by the Grant Agency of the Czech Republic and by the research project No. 253100002 sponsored by the Ministry of Education, Youth and Sports of the Czech Republic. Anastasios Sakalis acknowledges the support from the project No. HPRN-CT-2001-00180 ‘Training young researchers in miniaturized comprehensive liquid chromatography’, sponsored by the Commision of the European Communities, for his visit to the University of Pardubice.