Photodegradation of congo red using XeBr, KrCl and Cl2 barrier discharge excilamps: A kinetics study

Different physical, biological and chemical methods have been used to remove congo red mainly from textile industry effluents. All of these treatments usually transfer the contamination from one phase to another. In this work the oxidation of congo red using a combined advanced oxidation treatment based on photodegradation with UV radiation generated by KrCl. XeBr and Cl-2 excimer lamps in the presence of H2O2 has been studied. Experiments suggest that high congo red conversion values (>90%) were only reached with KrCl excilamp in the absence of H2O2. In the presence of a molar ratio H2O2/congo red of 12.5/1 KrCl excilamp totally removed congo red in 120 min whereas XeBr needed a molar ratio H2O2/congo red of 25/1 to attain total removal in the same time. Due to its low radiation intensity compared to the other two excilamps, Cl-2 excilamp never reached total removal of congo red in the experimental range assayed. Based on the experimental data, a pseudo-first order kinetic model for the three excilamps was proposed. A good correlation between experimental and calculated data was obtained. (C) 2011 Elsevier B.V. All rights reserved.