Decolorization and mineralization of diazo dye under artificial and solar light assisted Fenton and photo-Fenton conditions

The aim of this study is to verify the ability of some photochemical processes in the absence of light (Fenton) and in its presence (photolysis/UV, photo-Fenton/UV and photo-Fenton/Solar) to obtain total decolorization and mineralization of an diazo dye in aqueous solution: the Evans Blue (abbreviated as EB). Batch experiments were carried out to evaluate, on the first stage, the influence of different processes on EB decolorization and mineralization. During the second stage the optimal operational conditions like: H 2 O 2 dosage, EB concentration and source of light were investigated. The reaction efficiencies have been compared for the same system in the dark or under the assistance of an artificial or solar light source. The obtained results showed that color removal followed the increasing order: photolysis/UV (18.2%) < Fe(II)/H 2 O 2 (64.12%) < Fe(II)/H 2 O 2 /UV 365 nm (83.4%) < Fe(II)/H 2 O 2 /solar light (86.3%) < Fe(II)/H 2 O 2 /UV 254 nm (99.9%) with a reaction time of 60 min This improvement could be related to a better production of radicals OH • . In another hand, The efficiency of substrate mineralization in each process has been comparatively discussed by total organic carbon (TOC) and total chemical oxygen demand content of EB solutions.