Solar photocatalytic degradation of azo-dyes by photo-Fenton process

A solar photocatalytic degradation of the azo-dye acid orange 24 was carried out by means of a photo-Fenton reaction promoted by solar energy. The dye degradation was monitored during the experimental runs through UV/Vis absorption as well as COD and TOC concentration determination and toxicity reduction. In most cases, a discoloration higher than 85% was reached using 50 kJ/l of accumulated energy. In the case of the best reaction conditions, a discoloration of up to 95% and a toxicity reduction from 37 to 5 TU were accomplished with 50 kJ/l. In the same experiment, the removal of COD up to 88% and TOC up to 85% was reached after 105 kJ/l. Results consigned in this work are comparable to others reported in literature for different dyes. The reduction on toxicity values obtained by this methodology was most relevant and present dye degradation by the solar photo-Fenton process as an interesting alternative for coupling with biological processes. (c) 2005 Elsevier Ltd. All rights reserved.