Oxidation of bromocresol green by different advanced oxidation processes: Fenton, Fenton-like, photo-Fenton, photo-Fenton-like and solar light. Comparative study

The aim of this study is to test some advanced oxidation techniques (AOTs) in the absence of light (Fenton and Fenton-like) and in its presence (photo-Fenton and photo-Fenton-like) to obtain total decolorization of an anionic dye in aqueous solution: the bromocresol Green (CI Reactive Green 15 and abbreviated as BCG). Experiments were conducted on a laboratory-scale set up with all these processes. Best operatory conditions were found to be of pH 3, hydrogen peroxide to iron (II or III) molar ratio of 30: 1, artificial (254 nm) and solar light. Besides, several parameters were investigated like pH, oxygen, dose of H2O2, light effect, and reaction time. The obtained results showed that color removal followed the increasing order: Fe(III)/H2O2 < Fe(II)/H2O2 < Fe(II)/H2O2/Solar < Fe(II)/H2O2/UV254nm < Fe(III)/H2O2/UV254nm. This improvement could be related to a better production of radicals OH center dot. In another hand, decolorization kinetic followed pseudo-first-order type in all cases and no synergic effect was observed when Cu2+ ion (10(-4) M) was added to the solution of the dye.